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Each week the HouseGuests compete in several competitions in order to win power and safety inside the house, before voting off one of the HouseGuests during the eviction. The main elements of the format are as follows:
Before the sixteenth American season, HouseGuests competed in a Have/Have-Not challenge similar to the shopping tasks on "Big Brother UK" and other international editions. The winners become Haves and enjoy a full pantry of food, while Have-Nots, will be left with a staple diet of "slop" (fortified oatmeal), sleep in designated uncomfortable beds and take cold showers. In later seasons, the Haves & Have-Nots are determined either by the HoH themself or by the results of the HoH Competition.
When only two contestants remain, a jury formed of the most recently evicted HouseGuests (generally seven or nine) votes which of the two finalists wins the grand prize. Beginning in the fourth (2003) American season, jury members were sequestered off-site so that they would not be privy to the day-to-day goings-on in the house. ("Celebrity Big Brother US" does not sequester its jury members—all evicted celebrity HouseGuests vote on the winner.). The final Head of Household competition is split into three parts; the winners of the first two rounds compete in the third and final round. Once only two HouseGuests remain, the members of the jury cast their votes for who should win the series.
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In addition, American and Canadian "Big Brother" do not air a live launch show, as is customary in international editions—by the time the network show and live online feeds begin airing, it is not uncommon for at least one HouseGuest to already have been evicted. Also, the North American editions currently air only three times a week, compared with daily or six days a week for the recently rebooted British franchise. As a result, the TV episodes focus primarily on the main events regarding the gameplay and house politics versus the day-to-day goings-on in the house; to see the latter, watching the live feeds is necessary.
In 2013, English-speaking Canada introduced its own version of the show on the cable channel Slice; the series moved to Global TV for its third (2015) season. The show followed the American format but with more elaborate twists and greater viewer participation in the game. Secret tasks were introduced, usually presented by the show's mascot, "Marsha the Moose"; also, as in most global franchises, Big Brother was a distinct character who interacted with the HouseGuests. The French Canadian version mostly followed the American/Anglophone Canadian format, but the public could evict a housemate on some occasions and decided the winner.
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The 2020 revival of the "Big Brother Australia" series adopted a slightly altered version of the American format (having previously used the international format) while pre-recording the series months in advance. A "Nomination Challenge" is held to determine who holds the power to nominate for that round, with the winner naming three Nominations for Eviction. During each eviction, all Housemates (excluding the Nominating Housemate) vote to evict. There is no rule prohibiting individuals holding Nomination Power in consecutively between weeks and no Power of Veto is held. Additionally, the Australian public still decided the winner between the final 3.
"Big Brother Brasil" combines the American/Canadian and international formats. Brazil votes on evictions and the winner, but housemates compete for HoH, Power of Immunity, and Power of Veto; there is also a weekly shopping competition. HoH nominates one housemate for eviction, while the rest of the house nominates a second housemate. The winner of the Power of Immunity competition gets to choose someone to be safe from nomination.
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The pilot for ', which premiered exclusively online in 2015, had housemates voting on evictions but the public voting for the winner. A similar format was used for ', an online-only spin-off of the American series that ran in 2016.
The nineteenth series of "Big Brother UK" saw the adaption of the "Game Changer" competition which is very similar to the Power of Veto competition. The winner of this competition has the opportunity to save a nominee from eviction. Like the PoV, there are six people that play in the "Game Changer" competition. The process of how the contestants are chosen is different as the people who have been nominated play in the competition along with the richest housemate. If there are empty left in the competition, then the richest housemate hand picks who will playing in that weeks "Game Changer" competition. The winner of the competition, like the PoV, has the option to save housemate from eviction for the week or not use the power at all. Unlike the PoV however, if the winner does save someone then no replacement nominee was named leaving the remaining nominees up for eviction and facing the public vote.
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Other editions.
The "Big Brother" format has been otherwise modified in some countries:
There are also "test runs", with a group of celebrities (or journalists) living in the house for several days to test it. There are occasions where people who have auditioned for the show are also put in the house, most notably in the British edition, where many housemates claim to have met before. These series have been televised in Argentina, Bulgaria, Czech Republic, Germany, Mexico, the Pacific region, the Philippines and Spain. In some cases, it is not broadcast, but in others, such as the American edition, it is used as a promotional tool.
Versions.
As of , "Big Brother" has produced 513 winners in over 63 franchises.
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"Big Brother: The Game".
On 5 May 2020, Endemol Shine Group announced that an official "Big Brother" mobile game named "Big Brother: The Game" was being developed by Irish gaming company 9th Impact, with a worldwide release expected later that year. The game uses the American format, with competitions determining the Head of Household and Power of Veto holders, with an eviction cycle occurring each day. Players must form alliances with one another to stay in the game and advance to the next tier. Other users may spectate other games, but outside interference is strictly forbidden. Players were able to win up to $1,000,000 in prizes.
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A trial season took place in the Republic of Ireland during the summer of 2020. The player Aoife Cheung won a €5000 prize after surviving four evictions. The game was officially launched on 15 October 2020 worldwide for both iOS, Android devices and PC platforms.
The first season concluded on 29 July 2021 and was won by Amy Elizabeth, a 31-year-old special education teacher from Delaware who won a grand prize of $33,270.
On March 7, 2023, a third season of the game was announced to launch later that year on mobile and PC platforms, including Steam. The grand prize was stated to be for up to $1,000,000, with new features being added in response to fan feedback. However, no global third season took place, with a special British and Irish-only version launching to coincide with the show returning to ITV2 and ITVX, in an official partnership with the broadcaster. This version featured overhauled graphics, with Banijay announcing that previous games had reached 500K players.
Controversies.
Legal.
In April 2000, Castaway, an independent production company, filed a lawsuit against John de Mol and Endemol for stealing the concepts of their own show called "Survive!", a reality television show where contestants are placed on a deserted island and have to take care of themselves alone. These contestants were also filmed by cameras around them. The court later dismissed the lawsuit filed by Castaway against de Mol and Endemol. The "Survive!" reality television format was later turned into "Survivor".
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In 2000, the estate of George Orwell sued CBS Television and Endemol for copyright and trademark infringement, claiming that the program infringed on the Orwell novel "1984" and its trademarks. After a series of court rulings adverse to the defendants (CBS and Endemol), the case was settled for an undisclosed amount of money on the evening of the trial.
Sexual assault.
There have been three documented occurrences of possible rape happening during the show. In "Big Brother South Africa", a male housemate was accused of assaulting a fellow housemate while she was asleep. The pair were filmed kissing and cuddling in bed before the cameras moved away and the male housemate reportedly claimed to housemates the next day that he had intercourse with the contestant. However, the female housemate was apparently shocked by the claims and informed female housemates that she had not consented to have sex with him (under South African law, this act would be constituted as rape). This male housemate was expelled immediately after the allegations surfaced and was later arrested pending investigation, while the female housemate was removed from the house for her own protection and counselling. After this incident, the other housemates were warned not to attempt any further obscene actions, or they would be subject to a penalty of 43 years in prison and immediate expulsion from the house.
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In "Big Brother Brasil", many viewers reported that they watched a male housemate allegedly force himself on a female housemate while she was passed-out drunk after a "boozy party". Soon after, the Polícia Federal entered the house and arrested the offending housemate, who was later banned from ever appearing on the show again.
Additionally, an incident of sexual assault occurred in the Australian Big Brother house in 2006, during the show's sixth season. Contestant Michael "John" Bric held down fellow contestant Camilla Severi in her bed while a second man, Michael "Ashley" Cox, "slapped" her in the face with his penis, an indecent act illegal under Australian law. The incident was shown on the 'Adults-only' late-night segment, "Big Brother: Adults Only", leading to the show's cancellation. Both men involved in the incident were removed from the house. |
Bristol City F.C.
Bristol City Football Club is a professional football club based in Bristol, England. The team compete in the , the second level of the English football league system.
Founded in 1894, the club competed in the Southern League and Western League, being crowned Western League champions in 1897–98. They were admitted into the Football League in 1901 and won the Second Division in 1905–06. They finished second in the First Division the following season, three points behind champions Newcastle United, and went on to lose to Manchester United in the 1909 FA Cup final. Relegated in 1911, they dropped to the third tier in 1922, though would claim the Third Division South title in 1922–23 and again in 1926–27. They were returned to the third tier in 1932, remaining there until they won the Third Division South again in 1954–55. Having been relegated in 1960, Bristol City won promotion from the third tier in 1964–65 and then from the second tier in 1975–76. They played four seasons in the top-flight before being relegated in three consecutive seasons by 1982.
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Bristol City spent just two seasons in the Fourth Division and went on to win the Associate Members' Cup (Football League Trophy) in 1986. Promoted out of the Third Division in 1989–90, the club were relegated in 1995 and again in 1999 after another promotion in 1997–98. Bristol City won the Football League Trophy again in 2003, and were promoted from League One in 2006–07. Relegated after six seasons in the Championship, they won the Football League Trophy for a third time in 2015 on their way to the 2014–15 League One title, and have remained in the Championship since that promotion.
They have played their home games at Ashton Gate since moving from St John's Lane in 1904. The club's home colours are red and white, and their nickname is The Robins—a robin featured on the club's badge from 1976 to 1994 and from 2019 onwards. Their main rivals are Bristol Rovers, with whom they contest the Bristol derby, and Cardiff City, with whom they contest the cross-border Severnside derby.
History.
Early years and early successes (1894–1922).
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The club was founded in 1894 as Bristol South End and changed their name to Bristol City on adopting professionalism three years later when they were admitted into the Southern League. Finishing as runners-up in three of the first four seasons, in 1900 the club amalgamated with local Southern League rivals Bedminster F.C., who had been founded as Southville in 1887. Bristol City joined the Football League in 1901 when they became only the third club south of Birmingham (following in the footsteps of Woolwich Arsenal and Luton Town) to perform in the competition. Their first game in the Football League was on 7 September 1901 at Bloomfield Road, when Blackpool were beaten 2–0.
Winning the Second Division Championship with a record number of points when they became the first club in Football League history to win 30 league games in a season (out of 38 played) as well as equalling Manchester United's achievement of the previous season in winning 14 consecutive games (a record until 2018, also accomplished by Preston North End in 1950–51). Nicknamed the Bristol Babe at this time, they finished as runners-up in their inaugural First Division campaign (1906–07) as the only southern club to finish in the top two prior to World War I.
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In 1909 they won through to their only FA Cup final, though they were somewhat fortunate that a last-gasp spot-kick saved them from defeat in the semi-final versus Derby County at Stamford Bridge. In the final at the Crystal Palace (now the National Sports Centre) Bristol City lost to Manchester United 1–0. After a five-season stay in the top flight, despite winning 1–0 at Newcastle at the start of the 1910–11 campaign, failure to beat Everton in the season's finale brought City's first-ever taste of relegation and it was to be 65 years before top-flight status would be regained.
Bristol City would then go on to stay in Division 2 until three years after the First World War had ended, and in that time they reached the semi-finals of the 1919–20 FA Cup before being beaten 2–1 by Huddersfield Town and finished third in the Second Division in the 1920–21 season. However, in the next season they were relegated to the Third Division South.
The yo-yo era (1922–65).
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In 1946–47, City recorded a record league win by beating Aldershot 9–0, although despite Don Clark scoring 36 goals in the League, City failed to get promoted that season. Harry Dolman became chairman in 1949, a post he would hold for over 30 years. An engineer who had bought out the firm he worked for, he designed the first set of floodlights installed at Ashton Gate in the early 1950s. The late 1950s were a better time for City, with a five-year stay in the Second Division, a league they returned to for a further spell in 1965.
Back among the elite (1966–80).
In 1967, Alan Dicks was appointed manager, and things gradually began to improve, with promotion to the First Division in 1976, ending a 65-year exile from the top flight.
Between 1975 and 1981 City were regular participants in the Anglo-Scottish Cup, winning the trophy in 1977–78, beating Hibernian in the semi-finals, and winning 3–2 on aggregate in the final against St Mirren (managed at the time by a relatively new manager, Alex Ferguson). St Mirren had their revenge two seasons later, with an aggregate 5–1 victory over City to become the only Scottish team to win the trophy.
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City's second stint in the top flight was less successful than the club's first, with thirteenth position in 1979 being their highest finish during this era. Stars of this era included Peter Cormack, Geoff Merrick, Tom Ritchie, Clive Whitehead, Gerry Gow, Trevor Tainton and Jimmy Mann.
Financial difficulties and revival (1980–2000).
In 1980, the City team went back to the Second Division in the first of three relegations, their debt mounted and their financial losses increased, with two successive relegations following. Thus, in 1982, they fell into the Fourth Division, and were declared bankrupt. A new club was formed and BCFC (1982) Ltd acquired the club's player contracts. The highly paid senior players Julian Marshall, Chris Garland, Jimmy Mann, Peter Aitken, Geoff Merrick, David Rodgers, Gerry Sweeney and Trevor Tainton, who became known as the 'Ashton Gate Eight', each accepted termination of his contract for half the amount due. The club's previous owners had failed to pay its debts to many local businesses. The resulting ill will towards the club made it difficult for the new owners to obtain credit.
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City spent two seasons in the Fourth Division before winning promotion under Terry Cooper in 1984. They consolidated themselves in the Third Division during the latter part of the 1980s, and in 1990 Cooper's successor Joe Jordan achieved promotion as Third Division runners-up to local rivals Bristol Rovers.
There was a tragedy for the club, however, in that promotion campaign. In March 1990, two months before the club sealed promotion, striker Dean Horrix was killed in a car crash barely two weeks after joining the club, and having played three league games for them.
Jordan moved to Heart of Midlothian in September 1990, and his successor Jimmy Lumsden remained in charge for 18 months before making way for Denis Smith. Smith's first signing was the 20-year-old Arsenal striker Andy Cole. He was sold to Newcastle United in February 1993 and later played for Manchester United, where he collected five Premier League titles, two FA Cups and the European Cup.
Meanwhile, City remained in the new Division One (no longer the Second Division after the creation of the Premier League in 1992) and Smith moved to Oxford United in November 1993. His successor was Russell Osman. In January 1994 Osman led City to a shock 1–0 victory over Liverpool at Anfield in a third round replay in the FA Cup, a result that would cause the Liverpool manager at the time, Graeme Souness, to resign. Osman was sacked within a year of taking charge.
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Joe Jordan was brought back to Ashton Gate in September 1994, but was unable to prevent relegation to Division Two.
Jordan remained at the helm for two seasons after City's relegation, but left in March 1997 after failing to get them back into Division One. Former Bristol Rovers manager John Ward took over, and achieved promotion in 1998 as Division Two runners-up. But City struggled back in Division One, and Ward stepped down in October 1998 to be succeeded by Benny Lennartsson, their first non-British manager. City were relegated in bottom place and Lennartsson was dismissed in favour of Gillingham's Tony Pulis, who lasted six months before leaving to take over at Portsmouth. During his time at Ashton Gate he was manager of perhaps the worst City side since the one that completed a hat-trick of successive relegations almost 20 years earlier.
Coach Tony Fawthrop took over until the end of the season, when Danny Wilson was appointed. Wilson was arguably the most prominent manager to take charge of a City side since Denis Smith, as he had guided Barnsley to promotion to the Premier League in 1997 and Sheffield Wednesday to a 12th-place finish in 1999.
21st century.
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In the early 2000s Bristol City were regular Division Two play-off contenders during Wilson's spell as manager. They just missed out on the play-offs in 2002, finishing 7th. The following year, Wilson almost took them to automatic promotion, finishing 3rd and winning the Football League Trophy in Cardiff in 2003. The taste of the play-offs was bitter though, losing to rivals Cardiff City 1–0 on aggregate in the semi-final. In 2004, they finished in 3rd place again, and this time they reached the play-off final, but lost to Brighton & Hove Albion. He was sacked within days and replaced by veteran player Brian Tinnion.
City just failed to make the play-offs in Tinnion's first season as manager, finishing seventh, and he stepped down in September 2005 after a poor start to the season. Yeovil Town manager Gary Johnson was recruited as his successor in September 2005. Johnson led Bristol City to a 9th-place finish.
In the 2006–07 season, Bristol City finally achieved the elusive promotion that had evaded them in their 8 years in the third tier. Promotion to the Championship was confirmed on the final day of the season with a 3–1 win against already relegated Rotherham United, securing the runners-up place in the division and resulting in automatic promotion.
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After a good start in the Championship, City established themselves as real contenders, sitting in 3rd place at Christmas. By the start of March, City were top of the Championship, making an improbable second successive promotion a possibility. However, a poor run ended City's chances of an automatic promotion place but qualified for the play-offs with a 4th-place finish, their highest finish since 1980. City overcame Crystal Palace 4–2 on aggregate to progress to the play-off final at Wembley Stadium, where they were beaten 1–0 by Hull City.
After a poor start in the first half of the 2008–09 season, City recovered after Christmas, peaking at 4th place in late February. After a lot of draws, the season eventually petered out and City finished the season in tenth place. The 2009–10 season saw some good results in the autumn, but heavy defeats by local rivals Cardiff City (0–6) and Doncaster Rovers (2–5) in early 2010 led to much dissatisfaction amongst fans, and Johnson left the club on 18 March 2010. Assistant manager Keith Millen took charge as caretaker manager, and led a series of good results, resulting in a second successive tenth-place finish.
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Steve Coppell became manager in 2010 but resigned after just two matches. Longtime assistant manager Keith Millen was announced as Coppell's successor and City fell to a 15th-place finish in 2010–11. After a poor start to the 2011–12 season, Millen left the club in October 2011.
Derek McInnes was appointed next, but after a promising start, City fell into the relegation zone, eventually surviving in 20th place, their worst since promotion in 2007. This steady decline would continue and after a poor start to the 2012–13 season, McInnes was sacked in January 2013 with City bottom of the Championship. He was replaced by Sean O'Driscoll, the club's fifth head coach in three years, but City were relegated to League One after six seasons in the Championship. O'Driscoll left with the team 22nd in League One.
Steve Cotterill joined the club when Bristol City were second bottom of League One. Cotterill guided the club to a 12th-place finish. Bristol City were promoted back to the Championship after securing the League One title in 2014–15, their first league title since 1955. In their last home game, against Walsall, they finished the season with an 8–2 win. Bristol City finished the season with 99 points, the most points in a single season in the club's history, and 5 losses. In the same season, they also won the Football League Trophy after a win over Walsall, which finished 2–0 and their third league trophy, a record held by the club for having the most wins in that competition.
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Despite huge success in the previous season, the club struggled on their return to the second tier. Steve Cotterill was relieved of his duties in January 2016 after a poor run of form which had seen Bristol City slip to 22nd in the Championship table. Lee Johnson, former player and son of former manager, Gary Johnson, was appointed as Bristol City's new head coach on 6 February 2016. Bristol City eventually finished in 18th place.
In the 2016–17 season, City were only just able to accumulate enough points to ensure survival at the end of the season. Lee Johnson remained at the helm for the following season, again making a positive early start. At the midpoint of the season, after 24 league games, they sat second in the Championship, whilst also knocking out Premier League opposition in Watford, Stoke City, Crystal Palace and Manchester United to reach the semi-finals of the League Cup. However, City would eventually finish in 11th place.
Bristol City ended the 2018–19 season in 8th. The battle for the last play-off spot came down to the final day, before Derby County managed to win their final game and clinch it. From March to June, the 2019–20 season was suspended due to the COVID-19 pandemic. Despite again challenging for the play-offs during the season, Johnson was sacked on 4 July 2020 after a run of just one win in 10 league matches. His long-time assistant, Dean Holden, was appointed as his replacement on 10 August 2020. After suffering six straight defeats in all competitions, Holden was dismissed on 16 February 2021 after just six months in charge. He was replaced by Nigel Pearson.
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On 29 October 2023, Pearson was sacked with Bristol City 15th in the Championship following a run of 5 losses in 7 games. Despite the poor form, Pearson had overseen year on year points increases in his time at the club and many fans felt he has been undermined by a loss of key players such as Alex Scott and a lack of reinvestment in the playing squad.
On 7 November 2023, Liam Manning was appointed as the new head coach of Bristol City, joining from Oxford United.
Club identity.
Bristol City have played in red and white since the 1890s, occasionally also including black. The away kit is more variable. It is traditionally white, but has also featured black or yellow. Other colours featured have included green and a purple and lime combination, the latter of which has become a fan favourite.
About halfway through the 2007–08 season Bristol City manager Gary Johnson said in an interview that he hoped the team could get the whole ground bouncing. City supporters took this rallying cry on board and began to sing "Johnson says bounce around the ground" to the tune of Yellow Submarine, while continually bouncing up and down. The first game at which it was sung was in an away match against Southampton at St Mary's Stadium, and it was also sung at away at Queen's Park Rangers in February. When Bristol City fans travelled to London to play Charlton Athletic on 4 March 2008, the visiting fans, using the rail network to return home, adapted the song to "Bounce Around the Train". Since then, it has become an often used chant at Ashton Gate stadium by the fans. It was also sometimes used by supporters of Gary Johnson's former side Northampton Town, primarily at away matches. When Gary Johnson's son, Lee Johnson returned to his former club in 2016 as their new manager, he stated that he wished to inherit the chant and keep the fans singing it.
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Stadium.
Bristol City have played at Ashton Gate Stadium in the south-west of Bristol, just south of the River Avon, since moving from St John's Lane in 1904. The ground currently has an all-seated capacity of 27,000. It was the home of Bedminster until the 1900 merger, and the merged team played some games there the following season, but it did not become the permanent home of Bristol City until 1904.
In the past plans were considered for expansion work to be carried out at Ashton Gate. There were also proposals to build a new 36,000-seat stadium at Hengrove Park. This was turned down in a local referendum in December 2000. In 2002, the local council was looking at possible sites for a new 40,000-seat stadium which would house both City, Rovers and Bristol Rugby, but these plans were scrapped and it is widely accepted that this would not have been welcomed by the majority of supporters from all clubs. Ashton Gate's current capacity is an average size for Championship grounds; however, in November 2007 the club announced plans to relocate to a new 30,000-capacity stadium in Ashton Vale. Plans were also in place to increase capacity to 42,000 had England's 2018 World Cup bid been successful.
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The South stand opened for the 2015–16 season, with the existing Williams stand being demolished and replaced by the Lansdown stand in 2016. A new partly-artificial Desso pitch was laid and the current Dolman stand refurbished. A safe standing area was added to the south-east corner of the ground (roughly analogous to the old East End) in 2021.
A state-of-the-art training facility became operational in 2020. The Robins High Performance Centre is at Failand a short distance from Ashton Gate Stadium.
Rivalries.
Bristol City's traditional rivals are Bristol Rovers. The clubs have met 105 times, with the first meeting in 1897. Bristol City have the most wins on 43. However, the clubs have not been in the same league for a number of years; they were last in the same division in the 2000–01 season. Since then, they have only met three times; in the two-legged southern final of the 2006–07 Football League Trophy, which Rovers won 1–0 on aggregate, and in the first round of the 2013–14 Johnstone's Paint Trophy, which City won 2–1 at Ashton Gate.
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City's other main rivals are Cardiff City, who play in nearby Cardiff. Despite being a local derby, it crosses the Wales–England border, making it one of the few international club derbies in the United Kingdom. The two clubs have been at similar levels in recent years, being in the same division for 10 of the last 16 seasons. This has meant frequent meetings in the league including in the semi-finals of the 2003 Second Division play-offs. The biggest defeat in the Derby came in 2010 when Cardiff beat Bristol by 6 goals to 0.
Other clubs have been seen as 'third rivals' by the fans and media. Swindon Town are seen by many as rivals, nicknamed 'Swindle' by City fans. This rivalry was most recently relevant in the 2014–15 season, when the two clubs were rivals for promotion to the Championship. Plymouth Argyle have also previously been considered rivals despite a distance of over 100 miles. The rivalry was especially relevant in the 2000s when the two clubs were the highest-ranking West Country clubs for a number of years, and meetings were seen as a decider of the 'Best in the West'. Swansea City, Newport County, Cheltenham Town and even Yeovil Town have previously been mentioned as rivals, but very rarely. However, during a fixture between Bristol City and Swansea City on 2 February 2019 at Ashton Gate, fighting took place between Bristol City and Swansea City fans resulting in a rivalry flaring up between the two sets of fans.
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Records and statistics.
League history.
Source:
Note: The numbers in parentheses are the level of football for that season.
Most appearances.
Most club appearances including substitute appearances in all competitions (excluding Gloucestershire Cup). Updated 29 December 2013.
Note: On 29 December 2013, Louis Carey broke Bristol City's appearance record when he came on as a substitute in the 4–1 win over Stevenage. He overtook John Atyeo after 47 years and is now the club's all-time top appearance maker.
Most goals.
Correct as of 29 July 2018.
Players.
Notable players.
Former players
For a list of all Bristol City players with a Wikipedia article, see .
Bedminster merged with Bristol City in 1900; for a further list of all Bedminster players with articles see .
Club officials.
Management
Bristol City Women's.
The women's team was formed in 1990 supported by the club's community officer, Shaun Parker. Their greatest achievement was reaching the semi-finals of the FA Women's Cup in 1994 and winning promotion to the Premier League under Manager Jack Edgar in 2004. Following the decision by the FA to fund only one centre of excellence in Bristol, the two senior teams were disbanded in June 2008 and the girls' youth side merged with the Bristol Academy W.F.C. The majority of the senior players, with coach Will Roberts, moved to the University of Bath in summer 2008 and now play as AFC TeamBath Ladies in the South West Combination Women's Football League.
Honours.
Sources:
League
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Bioterrorism
Bioterrorism is terrorism involving the intentional release or dissemination of biological agents. These agents include bacteria, viruses, insects, fungi, and/or their toxins, and may be in a naturally occurring or a human-modified form, in much the same way as in biological warfare. Further, modern agribusiness is vulnerable to attacks by terrorists, and such attacks can seriously damage economy as well as consumer confidence. The latter destructive activity is called agrobioterrorism and is a subtype of agro-terrorism.
Definition.
Bioterrorism agents are typically found in nature, but could be mutated or altered to increase their ability to cause disease, make them resistant to current medicines, or to increase their ability to be spread into the environment. Biological agents can be spread through the air, water, or in food. Biological agents are attractive to terrorists because they are extremely difficult to detect and do not cause illness for several hours to several days. Some bioterrorism agents, like the smallpox virus, can be spread from person to person and some, like anthrax, cannot.
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Bioterrorism may be favored because biological agents are relatively easy and inexpensive to obtain, can be easily disseminated, and can cause widespread fear and panic beyond the actual physical damage. Military leaders, however, have learned that, as a military asset, bioterrorism has some important limitations; it is difficult to use a bioweapon in a way that only affects the enemy and not friendly forces. A biological weapon is useful to terrorists mainly as a method of creating mass panic and disruption to a state or a country. However, technologists such as Bill Joy have warned of the potential power which genetic engineering might place in the hands of future bio-terrorists.
The use of agents that do not cause harm to humans, but disrupt the economy, have also been discussed. One such pathogen is the foot-and-mouth disease (FMD) virus, which is capable of causing widespread economic damage and public concern (as witnessed in the 2001 and 2007 FMD outbreaks in the UK), while having almost no capacity to infect humans.
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History.
By the time World War I began, attempts to use anthrax were directed at animal populations. This generally proved to be ineffective.
Shortly after the start of World War I, Germany launched a biological sabotage campaign in the United States, Russia, Romania, and France. At that time, Anton Dilger lived in Germany, but in 1915 he was sent to the United States carrying cultures of glanders, a virulent disease of horses and mules. Dilger set up a laboratory in his home in Chevy Chase, Maryland. He used stevedores working the docks in Baltimore to infect horses with glanders while they were waiting to be shipped to Britain. Dilger was under suspicion as being a German agent, but was never arrested. Dilger eventually fled to Madrid, Spain, where he died during the Influenza Pandemic of 1918. In 1916, the Russians arrested a German agent with similar intentions. Germany and its allies infected French cavalry horses and many of Russia's mules and horses on the Eastern Front. These actions hindered artillery and troop movements, as well as supply convoys.
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In 1972, police in Chicago arrested two college students, Allen Schwander and Stephen Pera, who had planned to poison the city's water supply with typhoid and other bacteria. Schwander had founded a terrorist group, "R.I.S.E.", while Pera collected and grew cultures from the hospital where he worked. The two men fled to Cuba after being released on bail. Schwander died of natural causes in 1974, while Pera returned to the U.S. in 1975 and was put on probation.
In 1979, anthrax spores killed around 66 people after the spores were unintentionally released from a military lab near Sverdlovsk, Russia. This occurrence of inhalational anthrax had provided a majority of the knowledge scientists understand about clinical anthrax. Soviet officials and physicians claimed the epidemic was produced by the consumption of infected game meat, but further investigation proves the source of infection were the inhaled spores. There is continued discussion about the intentionality of the epidemic and some speculate it was calculated by the Soviet government.
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In 1980, the World Health Organization (WHO) announced the eradication of smallpox, a highly contagious and incurable disease. Although the disease has been eliminated in the wild, frozen stocks of smallpox virus are still maintained by the governments of the United States and Russia. Disastrous consequences are feared if rogue politicians or terrorists were to get hold of the smallpox strains. Since vaccination programs are now terminated, the world population is more susceptible to smallpox than ever before.
In Oregon in 1984, followers of the Bhagwan Shree Rajneesh attempted to control a local election by incapacitating the local population. They infected salad bars in 10 restaurants, produce in grocery stores, doorknobs, and other public domains with "Salmonella typhimurium" bacteria in the city of The Dalles, Oregon. The attack infected 751 people with severe food poisoning and hospitalized 45 of them. There were no fatalities. This incident was the first known bioterrorist attack in the United States in the 20th century. It was also the single largest bioterrorism attack on U.S. soil.
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In June 1993, the religious group Aum Shinrikyo released anthrax in Tokyo. Eyewitnesses reported a foul odor. The attack was a failure, because it did not infect a single person. The reason for this is due to the fact that the group used the vaccine strain of the bacterium. The spores which were recovered from the site of the attack showed that they were identical to an anthrax vaccine strain that was given to animals at the time. These vaccine strains are missing the genes that cause a symptomatic response.
In September and October 2001, several cases of anthrax broke out in the United States, apparently deliberately caused. Letters laced with infectious anthrax were concurrently delivered to news media offices and the U.S. Congress. The letters killed five people.
Scenarios.
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In the most common hoax scenario, no biological agents are employed. For instance, an envelope with powder in it that says, “You've just been exposed to anthrax.” Such hoaxes have been shown to have a large psychological impact on the population.
Anti-agriculture attacks are considered to require relatively little expertise and technology. Biological agents that attack livestock, fish, vegetation, and crops are mostly not contagious to humans and are therefore easier for attackers to handle. Even a few cases of infection can disrupt a country's agricultural production and exports for months, as evidenced by FMD outbreaks.
Types of agents.
Under current United States law, bio-agents which have been declared by the U.S. Department of Health and Human Services or the U.S. Department of Agriculture to have the "potential to pose a severe threat to public health and safety" are officially defined as "select agents." The CDC categorizes these agents (A, B or C) and administers the Select Agent Program, which regulates the laboratories which may possess, use, or transfer select agents within the United States. As with US attempts to categorize harmful recreational drugs, designer viruses are not yet categorized and avian H5N1 has been shown to achieve high mortality and human-communication in a laboratory setting.
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Category A.
These high-priority agents pose a risk to national security, can be easily transmitted and disseminated, result in high mortality, have potential major public health impact, may cause public panic, or require special action for public health preparedness.
Category B.
Category B agents are moderately easy to disseminate and have low mortality rates.
Category C.
Category C agents are emerging pathogens that might be engineered for mass dissemination because of their availability, ease of production and dissemination, high mortality rate, or ability to cause a major health impact.
Planning and monitoring.
Planning may involve the development of biological identification systems. Until recently in the United States, most biological defense strategies have been geared to protecting soldiers on the battlefield rather than ordinary people in cities. Financial cutbacks have limited the tracking of disease outbreaks. Some outbreaks, such as food poisoning due to "E. coli" or "Salmonella", could be of either natural or deliberate origin.
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Global defense strategies have also been put into place including the introduction of the Biological and Toxin Weapons Convention in 1975. A majority of countries across the globe participated in the conventions (144) but a handful chose not to take part in the defense. Many of the countries who opted out of the convention are located in the Middle East and former Soviet Union countries.
Preparedness.
Export controls on biological agents are not applied uniformly, providing terrorists a route for acquisition. Laboratories are working on advanced detection systems to provide early warning, identify contaminated areas and populations at risk, and to facilitate prompt treatment. Methods for predicting the use of biological agents in urban areas as well as assessing the area for the hazards associated with a biological attack are being established in major cities. In addition, forensic technologies are working on identifying biological agents, their geographical origins and/or their initial source. Efforts include decontamination technologies to restore facilities without causing additional environmental concerns.
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Early detection and rapid response to bioterrorism depend on close cooperation between public health authorities and law enforcement; however, such cooperation is lacking. National detection assets and vaccine stockpiles are not useful if local and state officials do not have access to them.
Aspects of protection against bioterrorism in the United States include:
On a CNN news broadcast in 2011, the CNN chief medical correspondent, Dr. Sanjay Gupta, weighed in on the American government's recent approach to bioterrorist threats. He explains how, even though the United States would be better fending off bioterrorist attacks now than they would be a decade ago, the amount of money available to fight bioterrorism over the last three years has begun to decrease. Looking at a detailed report that examined the funding decrease for bioterrorism in fifty-one American cities, Dr. Gupta stated that the cities "wouldn't be able to distribute vaccines as well" and "wouldn't be able to track viruses." He also said that film portrayals of global pandemics, such as "Contagion", were actually quite possible and may occur in the United States under the right conditions.
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A news broadcast by MSNBC in 2010 also stressed the low levels of bioterrorism preparedness in the United States. The broadcast stated that a bipartisan report gave the Obama administration a failing grade for its efforts to respond to a bioterrorist attack. The news broadcast invited the former New York City police commissioner, Howard Safir, to explain how the government would fare in combating such an attack. He said how "biological and chemical weapons are probable and relatively easy to disperse." Furthermore, Safir thought that efficiency in bioterrorism preparedness is not necessarily a question of money, but is instead dependent on putting resources in the right places. The broadcast suggested that the nation was not ready for something more serious.
In a September 2016 interview conducted by Homeland Preparedness News, Daniel Gerstein, a senior policy researcher for the RAND Corporation, stresses the importance in preparing for potential bioterrorist attacks on the nation. He implored the U.S. government to take the proper and necessary actions to implement a strategic plan of action to save as many lives as possible and to safeguard against potential chaos and confusion. He believes that because there have been no significant instances of bioterrorism since the anthrax attacks in 2001, the government has allowed itself to become complacent making the country that much more vulnerable to unsuspecting attacks, thereby further endangering the lives of U.S. citizens.
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Gerstein formerly served in the Science and Technology Directorate of the Department of Homeland Security from 2011 to 2014. He claims there has not been a serious plan of action since 2004 during George W. Bush's presidency, in which he issued a Homeland Security directive delegating responsibilities among various federal agencies. He also stated that the blatant mishandling of the Ebola virus outbreak in 2014 attested to the government's lack of preparation. This past May, legislation that would create a national defense strategy was introduced in the Senate, coinciding with the timing of ISIS-affiliated terrorist groups get closer to weaponizing biological agents. In May 2016, Kenyan officials apprehended two members of an Islamic extremist group in motion to set off a biological bomb containing anthrax. Mohammed Abdi Ali, the believed leader of the group, who was a medical intern, was arrested along with his wife, a medical student. The two were caught just before carrying out their plan. The Blue Ribbon Study Panel on Biodefense, which comprises a group of experts on national security and government officials, in which Gerstein had previously testified to, submitted its National Blueprint for Biodefense to Congress in October 2015 listing their recommendations for devising an effective plan.
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Bill Gates said in a February 18, 2017 "Business Insider" op-ed (published near the time of his Munich Security Conference speech) that it is possible for an airborne pathogen to kill at least 30 million people over the course of a year. In a "New York Times" report, the Gates Foundation predicted that a modern outbreak similar to the Spanish Influenza pandemic (which killed between 50 million and 100 million people) could end up killing more than 360 million people worldwide, even considering widespread availability of vaccines and other healthcare tools. The report cited increased globalization, rapid international air travel, and urbanization as increased reasons for concern. In a March 9, 2017, interview with CNBC, former U.S. Senator Joe Lieberman, who was co-chair of the bipartisan Blue Ribbon Study Panel on Biodefense, said a worldwide pandemic could end the lives of more people than a nuclear war. Lieberman also expressed worry that a terrorist group like ISIS could develop a synthetic influenza strain and introduce it to the world to kill civilians. In July 2017, Robert C. Hutchinson, former agent at the Department of Homeland Security, called for a "whole-of-government" response to the next global health threat, which he described as including strict security procedures at our borders and proper execution of government preparedness plans.
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Also, novel approaches in biotechnology, such as synthetic biology, could be used in the future to design new types of biological warfare agents. Special attention has to be laid on future experiments (of concern) that:
Most of the biosecurity concerns in synthetic biology, however, are focused on the role of DNA synthesis and the risk of producing genetic material of lethal viruses (e.g. 1918 Spanish flu, polio) in the lab. The CRISPR/Cas system has emerged as a promising technique for gene editing. It was hailed by The Washington Post as "the most important innovation in the synthetic biology space in nearly 30 years." While other methods take months or years to edit gene sequences, CRISPR speeds that time up to weeks. However, due to its ease of use and accessibility, it has raised a number of ethical concerns, especially surrounding its use in the biohacking space.
Biosurveillance.
In 1999, the University of Pittsburgh's Center for Biomedical Informatics deployed the first automated bioterrorism detection system, called RODS (Real-Time Outbreak Disease Surveillance). RODS is designed to collect data from many data sources and use them to perform signal detection, that is, to detect a possible bioterrorism event at the earliest possible moment. RODS, and other systems like it, collect data from sources including clinic data, laboratory data, and data from over-the-counter drug sales. In 2000, Michael Wagner, the codirector of the RODS laboratory, and Ron Aryel, a subcontractor, conceived the idea of obtaining live data feeds from "non-traditional" (non-health-care) data sources. The RODS laboratory's first efforts eventually led to the establishment of the National Retail Data Monitor, a system which collects data from 20,000 retail locations nationwide.
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On February 5, 2002, George W. Bush visited the RODS laboratory and used it as a model for a $300 million spending proposal to equip all 50 states with biosurveillance systems. In a speech delivered at the nearby Masonic temple, Bush compared the RODS system to a modern "DEW" line (referring to the Cold War ballistic missile early warning system).
The principles and practices of biosurveillance, a new interdisciplinary science, were defined and described in the "Handbook of Biosurveillance", edited by Michael Wagner, Andrew Moore and Ron Aryel, and published in 2006. Biosurveillance is the science of real-time disease outbreak detection. Its principles apply to both natural and man-made epidemics (bioterrorism).
Data which potentially could assist in early detection of a bioterrorism event include many categories of information. Health-related data such as that from hospital computer systems, clinical laboratories, electronic health record systems, medical examiner record-keeping systems, 911 call center computers, and veterinary medical record systems could be of help; researchers are also considering the utility of data generated by ranching and feedlot operations, food processors, drinking water systems, school attendance recording, and physiologic monitors, among others.
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In Europe, disease surveillance is beginning to be organized on the continent-wide scale needed to track a biological emergency. The system not only monitors infected persons, but attempts to discern the origin of the outbreak.
Researchers have experimented with devices to detect the existence of a threat:
Some research shows that ultraviolet avalanche photodiodes offer the high gain, reliability and robustness needed to detect anthrax and other bioterrorism agents in the air. The fabrication methods and device characteristics were described at the 50th Electronic Materials Conference in Santa Barbara on June 25, 2008. Details of the photodiodes were also published in the February 14, 2008, issue of the journal Electronics Letters and the November 2007 issue of the journal IEEE Photonics Technology Letters.
The United States Department of Defense conducts global biosurveillance through several programs, including the Global Emerging Infections Surveillance and Response System.
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Response to bioterrorism incident or threat.
Government agencies which would be called on to respond to a bioterrorism incident would include law enforcement, hazardous materials and decontamination units, and emergency medical units, if available.
The US military has specialized units, which can respond to a bioterrorism event; among them are the United States Marine Corps' Chemical Biological Incident Response Force and the U.S. Army's 20th Support Command (CBRNE), which can detect, identify, and neutralize threats, and decontaminate victims exposed to bioterror agents. US response would include the Centers for Disease Control.
Historically, governments and authorities have relied on quarantines to protect their populations. International bodies such as the World Health Organization already devote some of their resources to monitoring epidemics and have served clearing-house roles in historical epidemics.
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Bioterrorism can additionally harm the psychological aspect of victims and the general public. Victims exposed to biological weapons have shown an increased presence of clinical anxiety compared to the normal population.
Bill Gates has warned that bioterrorism could kill more people than nuclear war.
In February 2018, a CNN employee discovered on an airplane a "sensitive, top-secret document in the seatback pouch explaining how the Department of Homeland Security would respond to a bioterrorism attack at the Super Bowl."
2017 U.S. budget proposal affecting bioterrorism programs.
President Donald Trump promoted his first budget around keeping America safe. However, one aspect of defense would receive less money: "protecting the nation from deadly pathogens, man-made or natural," according to "The New York Times". Agencies tasked with biosecurity get a decrease in funding under the Administration's budget proposal.
For example:
"The next weapon of mass destruction may not be a bomb," Lawrence O. Gostin, the director of the World Health Organization's Collaborating Center on Public Health Law and Human Rights, told "The New York Times". "It may be a tiny pathogen that you can't see, smell or taste, and by the time we discover it, it'll be too late."
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Lack of international standards on public health experiments.
Tom Inglesy, the CEO and director of the Center for Health Security at the Johns Hopkins Bloomberg School of Public Health and an internationally recognized expert on public health preparedness, pandemic and emerging infectious disease said in 2017 that the lack of an internationally standardized approval process that could be used to guide countries in conducting public health experiments for resurrecting a disease that has already been eradicated increases the risk that the disease could be used in bioterrorism. This was in reference to the lab synthesis of horsepox in 2017 by researchers at the University of Alberta. The researchers recreated horsepox, an extinct cousin of the smallpox virus, in order to research new ways to treat cancer. |
Northrop B-2 Spirit
The Northrop B-2 Spirit, also known as the Stealth Bomber, is an American heavy strategic bomber, featuring low-observable stealth technology designed to penetrate dense anti-aircraft defenses. A subsonic flying wing with a crew of two, the plane was designed by Northrop (later Northrop Grumman) as the prime contractor, with Boeing, Hughes, and Vought as principal subcontractors, and was produced from 1987 to 2000. The bomber can drop conventional and thermonuclear weapons, such as up to eighty Mk 82 JDAM GPS-guided bombs, or sixteen B83 nuclear bombs. The B-2 is the only acknowledged in-service aircraft that can carry large air-to-surface standoff weapons in a stealth configuration.
Development began under the Advanced Technology Bomber (ATB) project during the Carter administration, which cancelled the Mach 2-capable B-1A bomber in part because the ATB showed such promise. But development difficulties delayed progress and drove up costs. Ultimately, the program produced 21 B-2s at an average cost of $2.13 billion (~$ billion in ), including development, engineering, testing, production, and procurement. Building each aircraft cost an average of US$737 million, while total procurement costs (including production, spare parts, equipment, retrofitting, and software support) averaged $929 million (~$ in ) per plane. The project's considerable capital and operating costs made it controversial in the U.S. Congress even before the winding down of the Cold War dramatically reduced the desire for a stealth aircraft designed to strike deep in Soviet territory. Consequently, in the late 1980s and 1990s lawmakers shrank the planned purchase of 132 bombers to 21.
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The B-2 can perform attack missions at altitudes of up to ; it has an unrefueled range of more than and can fly more than with one midair refueling. It entered service in 1997 as the second aircraft designed with advanced stealth technology, after the Lockheed F-117 Nighthawk attack aircraft. Primarily designed as a nuclear bomber, the B-2 was first used in combat to drop conventional, non-nuclear ordnance in the Kosovo War in 1999. It was later used in Iraq, Afghanistan, Libya and Yemen.
The United States Air Force has nineteen B-2s in service as of 2024; one was destroyed in a 2008 crash and another one damaged in a crash in 2022 was retired from service likely on account of the cost and duration of a potential repair. The Air Force plans to operate the B-2s until 2032, when the Northrop Grumman B-21 Raider is to replace them.
Development.
Origins.
By the mid-1970s, military aircraft designers had learned of a new method to avoid missiles and interceptors, known today as "stealth". The concept was to build an aircraft with an airframe that deflected or absorbed radar signals so that little was reflected back to the radar unit. An aircraft having radar stealth characteristics would be able to fly nearly undetected and could be attacked only by weapons and systems not relying on radar. Although other detection measures existed, such as human observation, infrared scanners, and acoustic locators, their relatively short detection range or poorly developed technology allowed most aircraft to fly undetected, or at least untracked, especially at night.
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In 1974, DARPA requested information from U.S. aviation firms about the largest radar cross-section of an aircraft that would remain effectively invisible to radars. Initially, Northrop and McDonnell Douglas were selected for further development. Lockheed had experience in this field with the development of the Lockheed A-12 and SR-71, which included several stealthy features, notably its canted vertical stabilizers, the use of composite materials in key locations, and the overall surface finish in radar-absorbing paint. A key improvement was the introduction of computer models used to predict the radar reflections from flat surfaces where collected data drove the design of a "faceted" aircraft. Development of the first such designs started in 1975 with the "Have Blue", a model Lockheed built to test the concept.
Plans were well advanced by the summer of 1975, when DARPA started the Experimental Survivability Testbed project. Northrop and Lockheed were awarded contracts in the first round of testing. Lockheed received the sole award for the second test round in April 1976 leading to the "Have Blue" program and eventually the F-117 stealth attack aircraft. Northrop also had a classified technology demonstration aircraft, the Tacit Blue in development in 1979 at Area 51. It developed stealth technology, LO (low observables), fly-by-wire, curved surfaces, composite materials, electronic intelligence, and Battlefield Surveillance Aircraft Experimental. The stealth technology developed from the program was later incorporated into other operational aircraft designs, including the B-2 stealth bomber.
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ATB program.
By 1976, these programs had progressed to a position in which a long-range strategic stealth bomber appeared viable. President Jimmy Carter became aware of these developments during 1977, and it appears to have been one of the major reasons the B-1 was canceled. Further studies were ordered in early 1978, by which point the "Have Blue" platform had flown and proven the concepts. During the 1980 presidential election campaign in 1979, Ronald Reagan repeatedly stated that Carter was weak on defense and used the B-1 as a prime example. In response, on 22 August 1980 the Carter administration publicly disclosed that the United States Department of Defense was working to develop stealth aircraft, including a bomber.
The Advanced Technology Bomber (ATB) program began in 1979. Full development of the black project followed, funded under the code name "Aurora". After the evaluations of the companies' proposals, the ATB competition was narrowed to the Northrop/Boeing and Lockheed/Rockwell teams with each receiving a study contract for further work. Both teams used flying wing designs. The Northrop proposal was code named "Senior Ice", and the Lockheed proposal code named "Senior Peg". Northrop had prior experience developing the YB-35 and YB-49 flying wing aircraft. The Northrop design was larger and had curved surfaces while the Lockheed design was faceted and included a small tail. In 1979, designer Hal Markarian produced a sketch of the aircraft that bore considerable similarities to the final design. The USAF originally planned to procure 165 ATB bombers.
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The Northrop team's ATB design was selected over the Lockheed/Rockwell design on 20 October 1981. The Northrop design received the designation B-2 and the name "Spirit". The bomber's design was changed in the mid-1980s when the mission profile was changed from high-altitude to low-altitude, terrain-following. The redesign delayed the B-2's first flight by two years and added about US$1 billion to the program's cost. An estimated US$23 billion was secretly spent for research and development on the B-2 by 1989. MIT engineers and scientists helped assess the mission effectiveness of the aircraft under a five-year classified contract during the 1980s. ATB technology was also fed into the Advanced Tactical Fighter program, which would result in the Lockheed YF-22 and Northrop YF-23, and later the Lockheed Martin F-22. Northrop was the B-2's prime contractor; major subcontractors included Boeing, Hughes Aircraft (now Raytheon), GE, and Vought Aircraft.
Secrecy and espionage.
During its design and development, the Northrop B-2 program was a black project; all program personnel needed a secret clearance. Still, it was less closely held than the Lockheed F-117 program; more people in the federal government knew about the B-2, and more information about the project was available. Both during development and in service, considerable effort has been devoted to maintaining the security of the B-2's design and technologies. Staff working on the B-2 in most, if not all, capacities need a level of special-access clearance and undergo extensive background checks carried out by a special branch of the USAF.
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A former Ford automobile assembly plant in Pico Rivera, California, was acquired and heavily rebuilt; the plant's employees were sworn to secrecy. To avoid suspicion, components were typically purchased through front companies, military officials would visit out of uniform, and staff members were routinely subjected to polygraph examinations. Nearly all information on the program was kept from the Government Accountability Office (GAO) and members of Congress until the mid-1980s.
The B-2 was first publicly displayed on 22 November 1988 at United States Air Force Plant 42 in Palmdale, California, where it was assembled. This viewing was heavily restricted, and guests were not allowed to see the rear of the B-2. However, "Aviation Week" editors found that there were no airspace restrictions above the presentation area and took aerial photographs of the aircraft's secret rear section with suppressed engine exhausts. The B-2's (s/n / AV-1) first public flight was on 17 July 1989 from Palmdale to Edwards Air Force Base.
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In 1984, Northrop employee Thomas Patrick Cavanagh was arrested for attempting to sell classified information from the Pico Rivera factory to the Soviet Union. Cavanagh was sentenced to life in prison in 1985 but released on parole in 2001. In October 2005, Noshir Gowadia, a design engineer who worked on the B-2's propulsion system, was arrested for selling classified information to China. Gowadia was convicted and sentenced to 32 years in prison.
Program costs and procurement.
A procurement of 132 aircraft was planned in the mid-1980s but was later reduced to 75. By the early 1990s the Soviet Union dissolved, effectively eliminating the Spirit's primary Cold War mission. Under budgetary pressures and Congressional opposition, in his 1992 State of the Union address, President George H. W. Bush announced B-2 production would be limited to 20 aircraft. In 1996, however, the Clinton administration, though originally committed to ending production of the bombers at 20 aircraft, authorized the conversion of a 21st bomber, a prototype test model, to Block 30 fully operational status at a cost of nearly $500 million (~$ in ). In 1995, Northrop made a proposal to the USAF to build 20 additional aircraft with a flyaway cost of $566 million each.
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The program was the subject of public controversy for its cost to American taxpayers. In 1996, the GAO disclosed that the USAF's B-2 bombers "will be, by far, the costliest bombers to operate on a per aircraft basis", costing over three times as much as the B-1B (US$9.6 million annually) and over four times as much as the B-52H (US$6.8 million annually). In September 1997, each hour of B-2 flight necessitated 119 hours of maintenance. Comparable maintenance needs for the B-52 and the B-1B are 53 and 60 hours, respectively, for each hour of flight. A key reason for this cost is the provision of air-conditioned hangars large enough for the bomber's wingspan, which are needed to maintain the aircraft's stealth properties, particularly its "low-observable" stealth skins. Maintenance costs are about $3.4 million per month for each aircraft. An August 1995 GAO report disclosed that the B-2 had trouble operating in heavy rain, as rain could damage the aircraft's stealth coating, causing procurement delays until an adequate protective coating could be found. In addition, the B-2's terrain-following/terrain-avoidance radar had difficulty distinguishing rain from other obstacles, rendering the subsystem inoperable during rain. However a subsequent report in October 1996 noted that the USAF had made some progress in resolving the issues with the radar via software fixes and hoped to have these fixes undergoing tests by the spring of 1997.
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The total "military construction" cost related to the program was projected to be US$553.6 million in 1997 dollars. The cost to procure each B-2 was US$737 million in 1997 dollars (equivalent to US$ billion in 2021), based only on a fleet cost of US$15.48 billion. The procurement cost per aircraft, as detailed in GAO reports, which include spare parts and software support, was $929 million per aircraft in 1997 dollars.
The total program cost projected through 2004 was US$44.75 billion in 1997 dollars (equivalent to US$ billion in 2021). This includes development, procurement, facilities, construction, and spare parts. The total program cost averaged US$2.13 billion per aircraft. The B-2 may cost up to $135,000 per flight hour to operate in 2010, which is about twice that of the B-52 and B-1.
Opposition.
In its consideration of the fiscal year 1990 defense budget, the House Armed Services Committee trimmed $800 million from the B-2 research and development budget, while at the same time staving off a motion to end the project. Opposition in committee and in Congress was mostly broad and bipartisan, with Congressmen Ron Dellums (D-CA), John Kasich (R-OH), and John G. Rowland (R-CT) authorizing the motion to end the project—as well as others in the Senate, including Jim Exon (D-NE) and John McCain (R-AZ) also opposing the project. Dellums and Kasich, in particular, worked together from 1989 through the early 1990s to limit production to 21 aircraft and were ultimately successful.
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The escalating cost of the B-2 program and evidence of flaws in the aircraft's ability to elude detection by radar were among factors that drove opposition to continue the program. At the peak production period specified in 1989, the schedule called for spending US$7 billion to $8 billion per year in 1989 dollars, something Committee Chair Les Aspin (D-WI) said "won't fly financially". In 1990, the Department of Defense accused Northrop of using faulty components in the flight control system; it was also found that redesign work was required to reduce the risk of damage to engine fan blades by bird ingestion.
In time, several prominent members of Congress began to oppose the program's expansion, including Senator John Kerry (D-MA), who cast votes against the B-2 in 1989, 1991, and 1992. By 1992, Bush had called for the cancellation of the B-2 and promised to cut military spending by 30% in the wake of the collapse of the Soviet Union. In October 1995, former Chief of Staff of the United States Air Force, General Mike Ryan, and former chairman of the Joint Chiefs of Staff, General John Shalikashvili, strongly recommended against Congressional action to fund the purchase of any additional B-2s, arguing that to do so would require unacceptable cuts in existing conventional and nuclear-capable aircraft, and that the military had greater priorities in spending a limited budget.
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Some B-2 advocates argued that procuring twenty additional aircraft would save money because B-2s would be able to deeply penetrate anti-aircraft defenses and use low-cost, short-range attack weapons rather than expensive standoff weapons. However, in 1995, the Congressional Budget Office (CBO) and its Director of National Security Analysis found that additional B-2s would reduce the cost of expended munitions by less than US$2 billion in 1995 dollars during the first two weeks of a conflict, in which the USAF predicted bombers would make their greatest contribution; this was a small fraction of the US$26.8 billion (in 1995 dollars) life cycle cost that the CBO projected for an additional 20 B-2s.
In 1997, as Ranking Member of the House Armed Services Committee and National Security Committee, Congressman Ron Dellums (D-CA), a long-time opponent of the bomber, cited five independent studies and offered an amendment to that year's defense authorization bill to cap production of the bombers to the existing 21 aircraft; the amendment was narrowly defeated. Nonetheless, Congress did not approve funding for additional B-2s.
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Further developments.
Several upgrade packages have been applied to the B-2. In July 2008, the B-2's onboard computing architecture was extensively redesigned; it now incorporates a new integrated processing unit that communicates with systems throughout the aircraft via a newly installed fiber optic network; a new version of the operational flight program software was also developed, with legacy code converted from the JOVIAL programming language to standard C. Updates were also made to the weapon control systems to enable strikes upon moving targets, such as ground vehicles.
On 29 December 2008, USAF officials awarded a US$468 million contract to Northrop Grumman to modernize the B-2 fleet's radars. Changing the radar's frequency was required as the United States Department of Commerce had sold that radio spectrum to another operator. In July 2009, it was reported that the B-2 had successfully passed a major USAF audit. In 2010, it was made public that the Air Force Research Laboratory had developed a new material to be used on the part of the wing trailing edge subject to engine exhaust, replacing existing material that quickly degraded.
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In July 2010, political analyst Rebecca Grant speculated that when the B-2 becomes unable to reliably penetrate enemy defenses, the Lockheed Martin F-35 Lightning II may take on its strike/interdiction mission, carrying B61 nuclear bombs as a tactical bomber. However, in March 2012, The Pentagon announced that a $2 billion, 10-year-long modernization of the B-2 fleet was to begin. The main area of improvement would be replacement of outdated avionics and equipment. Continued modernization efforts likely have continued in secret, as alluded to by a B-2 commander from Whiteman Air Force Base in April 2021, possibly indicating offensive weapons capability against threatening air defenses and aircraft. He stated:
It was reported in 2011 that The Pentagon was evaluating an unmanned stealth bomber, characterized as a "mini-B-2", as a potential replacement in the near future. In 2012, USAF Chief of Staff General Norton Schwartz stated the B-2's 1980s-era stealth technologies would make it less survivable in future contested airspaces, so the USAF is to proceed with the Next-Generation Bomber despite overall budget cuts. In 2012 projections, it was estimated that the Next-Generation Bomber would have an overall cost of $55 billion.
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In 2013, the USAF contracted for the Defensive Management System Modernization (DMS-M) program to replace the antenna system and other electronics to increase the B-2's frequency awareness. The Common Very Low Frequency Receiver upgrade allows the B-2s to use the same very low frequency transmissions as the "Ohio"-class submarines so as to continue in the nuclear mission until the Mobile User Objective System is fielded. In 2014, the USAF outlined a series of upgrades including nuclear warfighting, a new integrated processing unit, the ability to carry cruise missiles, and threat warning improvements. Due to ongoing software challenges, DMS-M was canceled by 2020, and the existing work was repurposed for cockpit upgrades.
In 1998, a Congressional panel advised the USAF to refocus resources away from continued B-2 production and instead begin development of a new bomber, either a new build or a variant of the B-2. In its 1999 bomber roadmap the USAF eschewed the panel's recommendations, believing its current bomber fleet could be maintained until the 2030s. The service believed that development could begin in 2013, in time to replace aging B-2s, B-1s and B-52s around 2037.
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Although the USAF previously planned to operate the B-2 until 2058, the FY 2019 budget moved up its retirement to "no later than 2032". It also moved the retirement of the B-1 to 2036 while extending the B-52's service life into the 2050s, because the B-52 has lower maintenance costs, versatile conventional payload, and the ability to carry nuclear cruise missiles (which the B-1 is treaty-prohibited from doing). The decision to retire the B-2 early was made because the small fleet of 20 is considered too expensive per plane to retain, with its position as a stealth bomber being taken over with the introduction of the B-21 Raider starting in the mid-2020s.
Design.
Overview.
The B-2 Spirit was developed to take over the USAF's vital penetration missions, allowing it to travel deep into enemy territory to deploy ordnance, which could include nuclear weapons. The B-2 is a flying wing aircraft, meaning that it has no fuselage or tail. It has significant advantages over previous bombers due to its blend of low-observable technologies with high aerodynamic efficiency and a large payload. Low observability provides greater freedom of action at high altitudes, thus increasing both range and field of view for onboard sensors. The USAF reports its range as approximately . At cruising altitude, the B-2 refuels every six hours, taking on up to of fuel at a time.
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The development and construction of the B-2 required pioneering use of computer-aided design and manufacturing technologies due to its complex flight characteristics and design requirements to maintain very low visibility to multiple means of detection. The B-2 bears a resemblance to earlier Northrop aircraft; the YB-35 and YB-49 were both flying wing bombers that had been canceled in development in the early 1950s, allegedly for political reasons. The resemblance goes as far as B-2 and YB-49 having the same wingspan. The YB-49 also had a small radar cross-section.
Approximately 80 pilots fly the B-2. Each aircraft has a crew of two, a pilot in the left seat and mission commander in the right, and has provisions for a third crew member if needed. For comparison, the B-1B has a crew of four and the B-52 has a crew of five. The B-2 is highly automated, and one crew member can sleep in a camp bed, use a toilet, or prepare a hot meal while the other monitors the aircraft, unlike most two-seat aircraft. Extensive sleep cycle and fatigue research was conducted to improve crew performance on long sorties. Advanced training is conducted at the USAF Weapons School.
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Armaments and equipment.
In the envisaged Cold War scenario, the B-2 was to perform deep-penetrating nuclear strike missions, making use of its stealthy capabilities to avoid detection and interception throughout the missions. There are two internal bomb bays in which munitions are stored either on a rotary launcher or two bomb-racks; the carriage of the weapons loadouts internally results in less radar visibility than external mounting of munitions. The B-2 is capable of carrying of ordnance. Nuclear ordnance includes the B61 and B83 nuclear bombs; the AGM-129 ACM cruise missile was also intended for use on the B-2 platform.
In light of the dissolution of the Soviet Union, it was decided to equip the B-2 for conventional precision attacks as well as for the strategic role of nuclear-strike. The B-2 features a sophisticated GPS-Aided Targeting System (GATS) that uses the aircraft's APQ-181 synthetic aperture radar to map out targets prior to the deployment of GPS-aided bombs (GAMs), later superseded by the Joint Direct Attack Munition (JDAM). In the B-2's original configuration, up to 16 GAMs or JDAMs could be deployed; An upgrade program in 2004 raised the maximum carrier capacity to 80 JDAMs.
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The B-2 has various conventional weapons in its arsenal, including Mark 82 and Mark 84 bombs, CBU-87 Combined Effects Munitions, GATOR mines, and the CBU-97 Sensor Fuzed Weapon. In July 2009, Northrop Grumman reported the B-2 was compatible with the equipment necessary to deploy the Massive Ordnance Penetrator (MOP), which is intended to attack reinforced bunkers; up to two MOPs could be equipped in the B-2's bomb bays with one per bay, the B-2 is the only platform compatible with the MOP as of 2012. As of 2011, the AGM-158 JASSM cruise missile is an upcoming standoff munition to be deployed on the B-2 and other platforms. This is to be followed by the Long Range Standoff Weapon, which may give the B-2 standoff nuclear capability for the first time.
Avionics and systems.
To make the B-2 more effective than previous bombers, many advanced and modern avionics systems were integrated into its design; these have been modified and improved following a switch to conventional warfare missions. One system is the low probability of intercept AN/APQ-181 multi-mode radar, a fully digital navigation system that is integrated with terrain-following radar and Global Positioning System (GPS) guidance, NAS-26 astro-inertial navigation system (first such system tested on the Northrop SM-62 Snark cruise missile) and a Defensive Management System (DMS) to inform the flight crew of possible threats. The onboard DMS is capable of automatically assessing the detection capabilities of identified threats and indicated targets. The DMS will be upgraded by 2021 to detect radar emissions from air defenses to allow changes to the auto-router's mission planning information while in-flight so it can receive new data quickly to plan a route that minimizes exposure to dangers.
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For safety and fault-detection purposes, an on-board test system is linked with the majority of avionics on the B-2 to continuously monitor the performance and status of thousands of components and consumables; it also provides post-mission servicing instructions for ground crews. In 2008, many of the 136 standalone distributed computers on board the B-2, including the primary flight management computer, were being replaced by a single integrated system. The avionics are controlled by 13 EMP-resistant MIL-STD-1750A computers, which are interconnected through 26 MIL-STD-1553B-busses; other system elements are connected via optical fiber.
In addition to periodic software upgrades and the introduction of new radar-absorbent materials across the fleet, the B-2 has had several major upgrades to its avionics and combat systems. For battlefield communications, both Link-16 and a high frequency satellite link have been installed, compatibility with various new munitions has been undertaken, and the AN/APQ-181 radar's operational frequency was shifted to avoid interference with other operators' equipment. The arrays of the upgraded radar features were entirely replaced to make the AN/APQ-181 into an active electronically scanned array (AESA) radar. Due to the B-2's composite structure, it is required to stay away from thunderstorms, to avoid static discharge and lightning strikes.
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Flight controls.
To address the inherent flight instability of a flying wing aircraft, the B-2 uses a complex quadruplex computer-controlled fly-by-wire flight control system that can automatically manipulate flight surfaces and settings without direct pilot inputs to maintain aircraft stability. The flight computer receives information on external conditions such as the aircraft's current air speed and angle of attack via pitot-static sensing plates, as opposed to traditional pitot tubes which would impair the aircraft's stealth capabilities. The flight actuation system incorporates both hydraulic and electrical servoactuated components, and it was designed with a high level of redundancy and fault-diagnostic capabilities.
Northrop had investigated several means of applying directional control that would infringe on the aircraft's radar profile as little as possible, eventually settling on a combination of split brake-rudders and differential thrust. Engine thrust became a key element of the B-2's aerodynamic design process early on; thrust not only affects drag and lift but pitching and rolling motions as well. Four pairs of control surfaces are located along the wing's trailing edge; while most surfaces are used throughout the aircraft's flight envelope, the inner elevons are normally only in use at slow speeds, such as landing. To avoid potential contact damage during takeoff and to provide a nose-down pitching attitude, all of the elevons remain drooped during takeoff until a high enough airspeed has been attained.
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Stealth.
The B-2's low-observable, or "stealth", characteristics enable the undetected penetration of sophisticated anti-aircraft defenses and to attack even heavily defended targets. This stealth comes from a combination of reduced acoustic, infrared, visual and radar signatures (multi-spectral camouflage) to evade the various detection systems that could be used to detect and be used to direct attacks against an aircraft. The B-2's stealth enables the reduction of supporting aircraft that are required to provide air cover, Suppression of Enemy Air Defenses and electronic countermeasures, making the bomber a "force multiplier". , there have been no instances of a missile being launched at a B-2.
To reduce optical visibility during daylight flights, the B-2 is painted in an anti-reflective paint. The undersides are dark because it flies at high altitudes (), and at that altitude a dark grey painting blends well into the sky. It is speculated to have an upward-facing light sensor which alerts the pilot to increase or reduce altitude to match the changing illuminance of the sky. The original design had tanks for a contrail-inhibiting chemical, but this was replaced in production aircraft by a contrail sensor that alerts the crew when they should change altitude. The B-2 is vulnerable to visual interception at ranges of or less. The B-2 is stored in a $5 million specialized air-conditioned hangar to maintain its stealth coating. Every seven years, this coating is carefully washed away with crystallized wheat starch so that the B-2's surfaces can be inspected for any dents or scratches.
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Radar.
The B-2's clean, low-drag flying wing configuration not only provides exceptional range but is also beneficial to reducing its radar profile. Reportedly, the B-2 has a radar cross-section (RCS) of about . The bomber does not always fly stealthily; when nearing air defenses pilots "stealth up" the B-2, a maneuver whose details are secret. The aircraft is stealthy, except briefly when the bomb bay opens. The flying wing design most closely resembles a so-called infinite flat plate (as vertical control surfaces dramatically increase RCS), the perfect stealth shape, as it would lack angles to reflect back radar waves (initially, the shape of the Northrop ATB concept was flatter; it gradually increased in volume according to specific military requirements). Without vertical surfaces to reflect radar laterally, side aspect radar cross section is also reduced. Radars operating at a lower frequency band (S or L band) are able to detect and track certain stealth aircraft that have multiple control surfaces, like canards or vertical stabilizers, where the frequency wavelength can exceed a certain threshold and cause a resonant effect.
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RCS reduction as a result of shape had already been observed on the Royal Air Force's Avro Vulcan strategic bomber, and the USAF's F-117 Nighthawk. The F-117 used flat surfaces (faceting technique) for controlling radar returns as during its development (see Lockheed Have Blue) in the early 1970s, technology only allowed for the simulation of radar reflections on simple, flat surfaces; computing advances in the 1980s made it possible to simulate radar returns on more complex curved surfaces. The B-2 is composed of many curved and rounded surfaces across its exposed airframe to deflect radar beams. This technique, known as "continuous curvature", was made possible by advances in computational fluid dynamics, and first tested on the Northrop Tacit Blue.
Infrared.
Some analysts claim infra-red search and track systems (IRSTs) can be deployed against stealth aircraft, because any aircraft surface heats up due to air friction and with a two channel IRST is a (4.3 μm absorption maxima) detection possible, through difference comparing between the low and high channel.
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Burying engines deep inside the fuselage also minimizes the thermal visibility or infrared signature of the exhaust. At the engine intake, cold air from the boundary layer below the main inlet enters the fuselage (boundary layer suction, first tested on the Northrop X-21) and is mixed with hot exhaust air just before the nozzles (similar to the Ryan AQM-91 Firefly). According to the Stefan–Boltzmann law, this results in less energy (thermal radiation in the infrared spectrum) being released and thus a reduced heat signature. The resulting cooler air is conducted over a surface composed of heat resistant carbon-fiber-reinforced polymer and titanium alloy elements, which disperse the air laterally, to accelerate its cooling. The B-2 lacks afterburners as the hot exhaust would increase the infrared signature; breaking the sound barrier would produce an obvious sonic boom as well as aerodynamic heating of the aircraft skin which would also increase the infrared signature.
Materials.
According to the Huygens–Fresnel principle, even a very flat plate would still reflect radar waves, though much less than when a signal is bouncing at a right angle. Additional reduction in its radar signature was achieved by the use of various radar-absorbent materials (RAM) to absorb and neutralize radar beams. The majority of the B-2 is made out of a carbon-graphite composite material that is stronger than steel, lighter than aluminum, and absorbs a significant amount of radar energy.
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The B-2 is assembled with unusually tight engineering tolerances to avoid leaks as they could increase its radar signature. Innovations such as alternate high frequency material (AHFM) and automated material application methods were also incorporated to improve the aircraft's radar-absorbent properties and reduce maintenance requirements. In early 2004, Northrop Grumman began applying a newly developed AHFM to operational B-2s. To protect the operational integrity of its sophisticated radar absorbent material and coatings, each B-2 is kept inside a climate-controlled hangar (Extra Large Deployable Aircraft Hangar System) large enough to accommodate its wingspan.
Shelter system.
B-2s are supported by portable, environmentally-controlled hangars called B-2 Shelter Systems (B2SS). The hangars are built by American Spaceframe Fabricators Inc. and cost approximately US$5 million apiece. The need for specialized hangars arose in 1998 when it was found that B-2s passing through Andersen Air Force Base did not have the climate-controlled environment maintenance operations required. In 2003, the B2SS program was managed by the Combat Support System Program Office at Eglin Air Force Base. B2SS hangars are known to have been deployed to Naval Support Facility Diego Garcia and RAF Fairford.
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Operational history.
1990s.
The first operational aircraft, christened "Spirit of Missouri", was delivered to Whiteman Air Force Base, Missouri, where the fleet is based, on 17 December 1993. The B-2 reached initial operational capability (IOC) on 1 January 1997. Depot maintenance for the B-2 is accomplished by USAF contractor support and managed at Oklahoma City Air Logistics Center at Tinker Air Force Base. Originally designed to deliver nuclear weapons, modern usage has shifted towards a flexible role with conventional and nuclear capability.
The B-2's combat debut was in 1999, during the Kosovo War. It was responsible for destroying 33% of selected Serbian bombing targets in the first eight weeks of U.S. involvement in the war. During this war, six B-2s flew non-stop to Yugoslavia from their home base in Missouri and back, totaling 30 hours. Although the bombers accounted 50 sorties out of a total of 34,000 NATO sorties, they dropped 11 percent of all bombs. The B-2 was the first aircraft to deploy GPS satellite-guided JDAM "smart bombs" in combat use in Kosovo. The use of JDAMs and precision-guided munitions effectively replaced the controversial tactic of carpet-bombing, which had been harshly criticized due to it causing indiscriminate civilian casualties in prior conflicts, such as the 1991 Gulf War. On 7 May 1999, a B-2 erroneously dropped five JDAMs on the Chinese Embassy due to an error in targeting instructions, killing three people and injuring 20. By then, the B-2 had dropped 500 bombs in Yugoslavia.
2000s.
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The B-2 saw service in Afghanistan, striking ground targets in support of Operation Enduring Freedom. With aerial refueling support, the B-2 flew one of its longest missions to date from Whiteman Air Force Base in Missouri to Afghanistan and back. B-2s would be stationed in the Middle East as a part of a US military buildup in the region from 2003.
The B-2's combat use preceded a USAF declaration of "full operational capability" in December 2003. The Pentagon's Operational Test and Evaluation 2003 Annual Report noted that the B-2's serviceability for Fiscal Year 2003 was still inadequate, mainly due to the maintainability of the B-2's low observable coatings. The evaluation also noted that the Defensive Avionics suite had shortcomings with "pop-up threats".
During the Iraq War, B-2s operated from Diego Garcia and an undisclosed "forward operating location". Other sorties in Iraq have launched from Whiteman AFB. the longest combat mission has been 44.3 hours. "Forward operating locations" have been previously designated as Andersen Air Force Base in Guam and RAF Fairford in the United Kingdom, where new climate controlled hangars have been constructed. B-2s have conducted 27 sorties from Whiteman AFB and 22 sorties from a forward operating location, releasing more than of munitions, including 583 JDAM "smart bombs" in 2003.
2010s.
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In response to organizational issues and high-profile mistakes made within the USAF, all of the B-2s, along with the nuclear-capable B-52s and the USAF's intercontinental ballistic missiles (ICBMs), were transferred to the newly formed Air Force Global Strike Command on 1 February 2010.
In March 2011, B-2s were the first U.S. aircraft into action in Operation Odyssey Dawn, the UN mandated enforcement of the Libyan no-fly zone. Three B-2s dropped 40 bombs on a Libyan airfield in support of the UN no-fly zone. The B-2s flew directly from the U.S. mainland across the Atlantic Ocean to Libya; a B-2 was refueled by allied tanker aircraft four times during each round trip mission.
In August 2011, "The New Yorker" reported that prior to the May 2011 U.S. Special Operations raid into Abbottabad, Pakistan that resulted in the death of Osama bin Laden, U.S. officials had considered an airstrike by one or more B-2s as an alternative; the use of a bunker busting bomb was rejected due to potential damage to nearby civilian buildings. There were also concerns an airstrike would make it difficult to positively identify Bin Laden's remains, making it hard to confirm his death.
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On 28 March 2013, two B-2s flew a round trip of from Whiteman Air Force base in Missouri to South Korea, dropping dummy ordnance on the Jik Do target range. The mission, part of the annual South Korean–U.S. military exercises, was the first time that B-2s overflew the Korean Peninsula. Tensions between the Koreas were high; North Korea protested against the B-2's participation and made threats of retaliatory nuclear strikes against South Korea and the United States.
On 18 January 2017, two B-2s attacked an ISIS training camp southwest of Sirte, Libya, killing around 85 militants. The B-2s together dropped 108 precision-guided Joint Direct Attack Munition (JDAM) bombs. These strikes were followed by an MQ-9 Reaper unmanned aerial vehicle firing Hellfire missiles. Each B-2 flew a 33-hour, round-trip mission from Whiteman Air Force Base, Missouri with four or five (accounts differ) refuelings during the trip.
2020s.
On 16 October 2024, B-2As carried out strikes on weapons storage facilities in Yemen, including underground facilities owned by the Houthis. Five hardened underground weapons storage locations were struck as part of the campaign against the Houthis for attacking international shipping during the Red Sea crisis. It was believed the strikes also served as a warning to Iran, demonstrating the stealth bomber's ability to destroy targets buried underground. RAAF Base Tindal in the Northern Territory, Australia was used as a staging ground for the strikes.
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Operators.
United States Air Force (19 aircraft in active inventory)
Accidents and incidents.
On 23 February 2008, B-2 "AV-12" "Spirit of Kansas" crashed on the runway shortly after takeoff from Andersen Air Force Base in Guam. "Spirit of Kansas" had been operated by the 393rd Bomb Squadron, 509th Bomb Wing, Whiteman Air Force Base, Missouri, and had logged 5,176 flight hours. The two-person crew ejected safely from the aircraft. The aircraft was destroyed, a hull loss valued at US$1.4 billion. After the accident, the USAF took the B-2 fleet off operational status for 53 days, returning on 15 April 2008. The cause of the crash was later determined to be moisture in the aircraft's Port Transducer Units during air data calibration, which distorted the information being sent to the bomber's air data system. As a result, the flight control computers calculated an inaccurate airspeed, and a negative angle of attack, causing the aircraft to pitch upward 30 degrees during takeoff. This was the first crash and loss of a B-2.
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In February 2010, a serious incident involving a B-2 occurred at Andersen Air Force Base in Guam. The aircraft involved was AV-11 "Spirit of Washington". The aircraft was severely damaged by fire while on the ground and underwent 18 months of repairs to enable it to fly back to the mainland U.S. for more comprehensive repairs. "Spirit of Washington" was repaired and returned to service in December 2013. At the time of the accident, the USAF had no training to deal with tailpipe fires on the B-2s.
On the night of 13–14 September 2021, B-2 "Spirit of Georgia" made an emergency landing at Whiteman AFB. The aircraft landed and went off the runway into the grass and came to rest on its left side. The cause was later determined to be faulty landing gear springs and "microcracking" in hydraulic connections on the aircraft. The lock link springs in the left landing gear had likely not been replaced in at least a decade, and produced about 11% less tension than specified. The "microcracking" reduced hydraulic support to the landing gear. These problems allowed the landing gear to fold upon landing. The accident resulted in a minimum of $10.1 million in repair damages, but the final repair cost was still being determined in March 2022.
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On 10 December 2022, an in-flight malfunction aboard a B-2 forced an emergency landing at Whiteman AFB. No personnel, including the flight crew, sustained injuries during the incident; there was a post-crash fire that was quickly put out. Subsequently, all B-2s were grounded. On 18 May 2023, Air Force officials lifted the grounding without disclosing any details about what caused the incident, or what steps had been taken return the aircraft to operation. In May 2024, the Air Force announced the B-2 would be divested, as it had been deemed to be "uneconomical to repair." Although no cost estimate was provided, the decision was likely influenced by the coming introduction of the B-21 bomber; after the B-2 crash in 2010, it took almost four years and over $100 million to return the aircraft to service because not losing one of the few penetrating bombers in the inventory was considered necessary to justify the effort. However, the impending arrival of the B-21 and coming retirement of the B-2 sometime after 2029 likely made USAF leaders decide it wouldn't be worth the expense to repair it, only for it to soon be retired.
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Aircraft on display.
No operational B-2s have been retired by the Air Force to be put on display. B-2s have made occasional appearances on ground display at various air shows.
B-2 test article (s/n AT-1000), the second of two built without engines or instruments and used for static testing, was placed on display in 2004 at the National Museum of the United States Air Force near Dayton, Ohio. The test article passed all structural testing requirements before the airframe failed. The museum's restoration team spent over a year reassembling the fractured airframe. The display airframe is marked to resemble "Spirit of Ohio" (S/N 82-1070), the B-2 used to test the design's ability to withstand extreme heat and cold. The exhibit features "Spirit of Ohio"s nose wheel door, with its "Fire and Ice" artwork, which was painted and signed by the technicians who performed the temperature testing. The restored test aircraft is on display in the museum's "Cold War Gallery". |
Beaver
Beavers (genus Castor) are large, semiaquatic rodents of the Northern Hemisphere. There are two existing species: the North American beaver ("Castor canadensis") and the Eurasian beaver ("C. fiber"). Beavers are the second-largest living rodents, after capybaras, weighing up to . They have stout bodies with large heads, long chisel-like incisors, brown or gray fur, hand-like front feet, webbed back feet, and tails that are flat and scaly. The two species differ in skull and tail shape and fur color. Beavers can be found in a number of freshwater habitats, such as rivers, streams, lakes and ponds. They are herbivorous, consuming tree bark, aquatic plants, grasses and sedges.
Beavers build dams and lodges using tree branches, vegetation, rocks and mud; they chew down trees for building material. Dams restrict water flow, forming ponds, and lodges (usually built in ponds) serve as shelters. Their infrastructure creates wetlands used by many other species, and because of their effect on other organisms in the ecosystem, beavers are considered a keystone species. Adult males and females live in monogamous pairs with their offspring. After their first year, the young help their parents repair dams and lodges; older siblings may also help raise newly born offspring. Beavers hold territories and mark them using scent mounds made of mud, debris, and castoreum—a liquid substance excreted through the beaver's urethra-based castor sacs. Beavers can also recognize their kin by their anal gland secretions and are more likely to tolerate them as neighbors.
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Historically, beavers have been hunted for their fur, meat, and castoreum. Castoreum has been used in medicine, perfume, and food flavoring; beaver pelts have been a major driver of the fur trade. Before protections began in the 19th and early 20th centuries, overhunting had nearly exterminated both species. Their populations have since rebounded, and they are listed as species of least concern by the IUCN Red List of mammals. In human culture, the beaver symbolizes industriousness, especially in connection with construction; it is the national animal of Canada.
Etymology.
The English word "beaver" comes from the Old English word or and is connected to the German word and the Dutch word . The ultimate origin of the word is an Indo-European root for . Cognates of "beaver" are the source for several European placenames, including those of Beverley, Bièvres, Biberbach, Biebrich, Bibra, Bibern, Bibrka, Bobr, Bober, Bóbrka, Bjurholm, Bjurälven, and Bjurum. The genus name "Castor" has its origin in the Greek word and translates as .
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Taxonomy.
Carl Linnaeus coined the genus name "Castor" as well as the specific (species) epithet "fiber" for the Eurasian species. German zoologist Heinrich Kuhl coined "C. canadensis" in 1820. Many scientists considered both names synonymous for one same species until the 1970s, when chromosomal evidence became available confirming both as separate where the Eurasian has 48 chromosomes, while the North American has 40. The difference in chromosome numbers prevents them from interbreeding. Twenty-five subspecies have been classified for "C. canadensis", and nine have been classified for "C. fiber".
There are two extant species: the North American beaver ("Castor canadensis") and the Eurasian beaver ("C. fiber"). The Eurasian beaver is slightly longer and has a more lengthened skull, triangular nasal cavities (as opposed to the square ones of the North American species), a lighter fur color, and a narrower tail.
Evolution.
Beavers belong to the rodent suborder Castorimorpha, along with Heteromyidae (kangaroo rats and kangaroo mice), and the gophers. Modern beavers are the only extant members of the family Castoridae. They originated in North America in the late Eocene and colonized Eurasia via the Bering Land Bridge in the early Oligocene, coinciding with the "Grande Coupure", a time of significant changes in animal species around 33million years ago (myr).
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The more basal castorids had several unique features: more complex occlusion between cheek teeth, parallel rows of upper teeth, premolars that were only slightly smaller than molars, the presence of a third set of premolars (P3), a hole in the stapes of the inner ear, a smooth palatine bone (with the palatine opening closer to the rear end of the bone), and a longer snout. More derived castorids have less complex occlusion, upper tooth rows that create a V-shape towards the back, larger second premolars compared to molars, absence of a third premolar set and stapes hole, a more grooved palatine (with the opening shifted towards the front), and reduced incisive foramen. Members of the subfamily "Palaeocastorinae" appeared in late-Oligocene North America. This group consisted primarily of smaller animals with relatively large front legs, a flattened skull, and a reduced tail—all features of a fossorial (burrowing) lifestyle.
In the early Miocene (about 24 mya), castorids evolved a semiaquatic lifestyle. Members of the subfamily Castoroidinae are considered to be a sister group to modern beavers, and included giants like "Castoroides" of North America and "Trogontherium" of Eurasia. "Castoroides" is estimated to have had a length of and a weight of . Fossils of one genus in Castoroidinae, "Dipoides", have been found near piles of chewed wood, though "Dipoides" appears to have been an inferior woodcutter compared to "Castor". Researchers suggest that modern beavers and Castoroidinae shared a bark-eating common ancestor. Dam and lodge-building likely developed from bark-eating, and allowed beavers to survive in the harsh winters of the subarctic. There is no conclusive evidence for this behavior occurring in non-"Castor" species.
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The genus "Castor" likely originated in Eurasia. The earliest fossil remains appear to be "C. neglectus", found in Germany and dated 12–10 mya. Mitochondrial DNA studies place the common ancestor of the two living species at around 8 mya. The ancestors of the North American beaver would have crossed the Bering Land Bridge around 7.5 mya. "Castor" may have competed with members of Castoroidinae, which led to niche differentiation. The fossil species "C. praefiber" was likely an ancestor of the Eurasian beaver. "C. californicus" from the Early Pleistocene of North America was similar to but larger than the extant North American beaver.'
Characteristics.
Beavers are the second-largest living rodents, after capybaras. They have a head–body length of , with a tail, a shoulder height of , and generally weigh , but can be as heavy as . Males and females are almost identical externally. Their bodies are streamlined like marine mammals and their robust build allows them to pull heavy loads. A beaver coat has 12,000–23,000 hairs/cm2 (77,000–148,000 hairs/in2) and functions to keep the animal warm, to help it float in water, and to protect it against predators. Guard hairs are long and typically reddish brown, but can range from yellowish brown to nearly black. The underfur is long and dark gray. Beavers molt every summer.
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Beavers have large skulls with powerful chewing muscles. They have four chisel-shaped incisors that continue to grow throughout their lives. The incisors are covered in a thick enamel that is colored orange or reddish-brown by iron compounds. The lower incisors have roots that are almost as long as the entire lower jaw. Beavers have one premolar and three molars on all four sides of the jaws, adding up to 20 teeth. The molars have meandering ridges for grinding woody material. The eyes, ears and nostrils are arranged so that they can remain above water while the rest of the body is submerged. The nostrils and ears have valves that close underwater, while nictitating membranes cover the eyes. To protect the larynx and trachea from water flow, the epiglottis is contained within the nasal cavity instead of the throat. In addition, the back of the tongue can rise and create a waterproof seal. A beaver's lips can close behind the incisors, preventing water from entering their mouths as they cut and bite onto things while submerged.
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The beaver's front feet are dexterous, allowing them to grasp and manipulate objects and food, as well as dig. The hind feet are larger and have webbing between the toes, and the second innermost toe has a "double nail" used for grooming. Beavers can swim at ; only their webbed hind feet are used to swim, while the front feet fold under the chest. On the surface, the hind limbs thrust one after the other; while underwater, they move at the same time. Beavers are awkward on land but can move quickly when they feel threatened. They can carry objects while walking on their hind legs.
The beaver's distinctive tail has a conical, muscular, hairy base; the remaining two-thirds of the appendage is flat and scaly. The tail has multiple functions: it provides support for the animal when it is upright (such as when chewing down a tree), acts as a rudder when it is swimming, and stores fat for winter. It also has a countercurrent blood vessel system which allows the animal to lose heat in warm temperatures and retain heat in cold temperatures.
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The beaver's sex organs are inside the body, and the male's penis has a cartilaginous baculum. They have only one opening, a cloaca, which is used for reproduction, scent-marking, defecation, and urination. The cloaca evolved secondarily, as most mammals have lost this feature, and may reduce the area vulnerable to infection in dirty water. The beaver's intestine is six times longer than its body, and the caecum is double the volume of its stomach. Microorganisms in the caecum allow them to process around 30 percent of the cellulose they eat. A beaver defecates in the water, leaving behind balls of sawdust. Female beavers have four mammary glands; these produce milk with 19 percent fat, a higher fat content than other rodents. Beavers have two pairs of glands: castor sacs, which are part of the urethra, and anal glands. The castor sacs secrete castoreum, a liquid substance used mainly for marking territory. Anal glands produce an oily substance which the beaver uses as a waterproof ointment for its coat. The substance plays a role in individual and family recognition. Anal secretions are darker in females than males among Eurasian beavers, while the reverse is true for the North American species.
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Compared to many other rodents, a beaver's brain has a hypothalamus that is much smaller than the cerebrum; this indicates a relatively advanced brain with higher intelligence. The cerebellum is large, allowing the animal to move within a three-dimensional space (such as underwater) similar to tree-climbing squirrels. The neocortex is devoted mainly to touch and hearing. Touch is more advanced in the lips and hands than the whiskers and tail. Vision in the beaver is relatively poor; the beaver eye cannot see as well underwater as an otter. Beavers have a good sense of smell, which they use for detecting land predators and for inspecting scent marks, food, and other individuals.
Beavers can hold their breath for as long as 15 minutes but typically remain underwater for no more than five or six minutes. Dives typically last less than 30 seconds and are usually no more than deep. When diving, their heart rate decreases to 60 beats per minute, half its normal pace, and blood flow is directed more towards the brain. A beaver's body also has a high tolerance for carbon dioxide. When surfacing, the animal can replace 75 percent of the air in its lungs in one breath, compared to 15 percent for a human.
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Distribution and status.
The IUCN Red List of mammals lists both beaver species as least concern. The North American beaver is widespread throughout most of the United States and Canada and can be found in northern Mexico. The species was introduced to Finland in 1937 (and then spread to northwestern Russia) and to Tierra del Fuego, Patagonia, in 1946. , the introduced population of North American beavers in Finland has been moving closer to the habitat of the Eurasian beaver. Historically, the North American beaver was trapped and nearly extirpated because its fur was highly sought after. Protections have allowed the beaver population on the continent to rebound to an estimated 6–12million by the late 20th century; still far lower than the originally estimated 60–400million North American beavers before the fur trade. The introduced population in Tierra del Fuego is estimated at 35,000–50,000 individuals .
The Eurasian beaver's range historically included much of Eurasia, but was decimated by hunting by the early 20th century. In Europe, beavers were reduced to fragmented populations, with combined population numbers being estimated at 1,200 individuals for the Rhône of France, the Elbe in Germany, southern Norway, the Neman river and Dnieper Basin in Belarus, and the Voronezh river in Russia. The beaver has since recolonized parts of its former range, aided by conservation policies and reintroductions. Beaver populations now range across western, central, and eastern Europe, and western Russia and the Scandinavian Peninsula. Beginning in 2009, beavers have been successfully reintroduced to parts of Great Britain. , the total Eurasian beaver population in Europe was estimated at over one million. Small native populations are also present in Mongolia and northwestern China; their numbers were estimated at 150 and 700, respectively, . Under New Zealand's Hazardous Substances and New Organisms Act 1996, beavers are classed as a "prohibited new organism" preventing them from being introduced into the country.
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Ecology.
Beavers live in freshwater ecosystems such as rivers, streams, lakes and ponds. Water is the most important component of beaver habitat; they swim and dive in it, and it provides them refuge from land predators. It also restricts access to their homes and allows them to move building objects more easily. Beavers prefer slower moving streams, typically with a gradient (steepness) of one percent, though they have been recorded using streams with gradients as high as 15 percent. Beavers are found in wider streams more often than in narrower ones. They also prefer areas with no regular flooding and may abandon a location for years after a significant flood.
Beavers typically select flat landscapes with diverse vegetation close to the water. North American beavers prefer trees being or less from the water, but will roam several hundred meters to find more. Beavers have also been recorded in mountainous areas. Dispersing beavers will use certain habitats temporarily before finding their ideal home. These include small streams, temporary swamps, ditches, and backyards. These sites lack important resources, so the animals do not stay there permanently. Beavers have increasingly settled at or near human-made environments, including agricultural areas, suburbs, golf courses, and shopping malls.
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Beavers have an herbivorous and a generalist diet. During the spring and summer, they mainly feed on herbaceous plant material such as leaves, roots, herbs, ferns, grasses, sedges, water lilies, water shields, rushes, and cattails. During the fall and winter, they eat more bark and cambium of woody plants; tree and shrub species consumed include aspen, birch, oak, dogwood, willow and alder. There is some disagreement about why beavers select specific woody plants; some research has shown that beavers more frequently select species which are more easily digested, while others suggest beavers principally forage based on stem size. Beavers may cache their food for the winter, piling wood in the deepest part of their pond where it cannot be reached by other browsers. This cache is known as a "raft"; when the top becomes frozen, it creates a "cap". The beaver accesses the raft by swimming under the ice. Many populations of Eurasian beaver do not make rafts, but forage on land during winter.
Beavers usually live up to 10 years. Felids, canids, and bears may prey upon them. Beavers are protected from predators when in their lodges, and prefer to stay near water. Parasites of the beaver include the bacteria "Francisella tularensis", which causes tularemia; the protozoan "Giardia duodenalis", which causes giardiasis (beaver fever); and the beaver beetle and mites of the genus "Schizocarpus". They have also been recorded to be infected with the rabies virus.
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Infrastructure.
Beavers need trees and shrubs to use as building material for dams, which restrict flowing water to create a pond for them to live in, and for lodges, which act as shelters and refuges from predators and the elements. Without such material, beavers dig burrows into a bank to live. Dam construction begins in late summer or early fall, and they repair them whenever needed. Beavers can cut down trees up to wide in less than 50 minutes. Thicker trees, at wide or more, may not fall for hours. When chewing down a tree, beavers switch between biting with the left and right side of the mouth. Tree branches are then cut and carried to their destination with the powerful jaw and neck muscles. Other building materials, like mud and rocks, are held by the forelimbs and tucked between the chin and chest.
Beavers start building dams when they hear running water, and the sound of a leak in a dam triggers them to repair it. To build a dam, beavers stack up relatively long and thick logs between banks and in opposite directions. Heavy rocks keep them stable, and grass is packed between them. Beavers continue to pile on more material until the dam slopes in a direction facing upstream. Dams can range in height from to and can stretch from to several hundred meters long. Beaver dams are more effective in trapping and slowly leaking water than man-made concrete dams. Lake-dwelling beavers do not need to build dams.
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Beavers make two types of lodges: bank lodges and open-water lodges. Bank lodges are burrows dug along the shore and covered in sticks while the more complex freestanding, open-water lodges are built over a platform of piled-up sticks. The lodge is mostly sealed with mud, except for a hole at the top which acts as an air vent. Both types are accessed by underwater entrances. The above-water space inside the lodge is known as the "living chamber", and a "dining area" may exist close to the water entrance. Families routinely clean out old plant material and bring in new material.
North American beavers build more open-water lodges than Eurasian beavers. Beaver lodges built by new settlers are typically small and sloppy. More experienced families can build structures with a height of and an above-water diameter of . A lodge sturdy enough to withstand the coming winter can be finished in just two nights. Both lodge types can be present at a beaver site. During the summer, beavers tend to use bank lodges to keep cool and use open-water lodges during the winter. The air vent provides ventilation, and newly added carbon dioxide can be cleared in an hour. The lodge remains consistent in oxygen and carbon dioxide levels from season to season.
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Beavers in some areas will dig canals connected to their ponds. The canals fill with groundwater and give beavers access and easier transport of resources, as well as allow them to escape predators. These canals can stretch up to wide, deep, and over long. It has been hypothesized that beavers' canals are not only transportation routes but an extension of their "central place" around the lodge and/or food cache. As they drag wood across the land, beavers leave behind trails or "slides", which they reuse when moving new material.
Environmental effects.
The beaver works as an ecosystem engineer and keystone species, as its activities can have a great impact on the landscape and biodiversity of an area. Aside from humans, few other extant animals appear to do more to shape their environment. When building dams, beavers alter the paths of streams and rivers, allowing for the creation of extensive wetland habitats. In one study, beavers were associated with large increases in open-water areas. When beavers returned to an area, 160% more open water was available during droughts than in previous years, when they were absent. Beaver dams also lead to higher water tables in mineral soil environments and in wetlands such as peatlands. In peatlands particularly, their dams stabilize the constantly changing water levels, leading to greater carbon storage.
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Beaver ponds, and the wetlands that succeed them, remove sediments and pollutants from waterways, and can stop the loss of important soils. These ponds can increase the productivity of freshwater ecosystems by accumulating nitrogen in sediments. Beaver activity can affect the temperature of the water; in northern latitudes, ice thaws earlier in the warmer beaver-dammed waters. Beavers may contribute to climate change. In Arctic areas, the floods they create can cause permafrost to thaw, releasing methane into the atmosphere.
As wetlands are formed and riparian habitats are enlarged, aquatic plants colonize the newly available watery habitat. One study in the Adirondacks found that beaver engineering lead to an increase of more than 33 percent in herbaceous plant diversity along the water's edge. Another study in semiarid eastern Oregon found that the width of riparian vegetation on stream banks increased several-fold as beaver dams watered previously dry terraces adjacent to the stream. Riparian ecosystems in arid areas appear to sustain more plant life when beaver dams are present. Beaver ponds act as a refuge for riverbank plants during wildfires, and provide them with enough moisture to resist such fires. Introduced beavers at Tierra del Fuego have been responsible for destroying the indigenous forest. Unlike trees in North America, many trees in South America cannot grow back after being cut down.
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Beaver activity impacts communities of aquatic invertebrates. Damming typically leads to an increase of slow or motionless water species, like dragonflies, oligochaetes, snails, and mussels. This is to the detriment of rapid water species like black flies, stoneflies, and net-spinning caddisflies. Beaver floodings create more dead trees, providing more habitat for terrestrial invertebrates like "Drosophila" flies and bark beetles, which live and breed in dead wood. The presence of beavers can increase wild salmon and trout populations, and the average size of these fishes. These species use beaver habitats for spawning, overwintering, feeding, and as havens from changes in water flow. The positive effects of beaver dams on fish appear to outweigh the negative effects, such as blocking of migration. Beaver ponds have been shown to be beneficial to frog populations by protecting areas for larvae to mature in warm water. The stable waters of beaver ponds also provide ideal habitat for freshwater turtles.
Beavers help waterfowl by creating increased areas of water. The widening of the riparian zone associated with beaver dams has been shown to increase the abundance and diversity of birds favoring the water's edge, an impact that may be especially important in semi-arid climates. Fish-eating birds use beaver ponds for foraging, and in some areas, certain species appear more frequently at sites where beavers were active than at sites with no beaver activity. In a study of Wyoming streams and rivers, watercourses with beavers had 75 times as many ducks as those without. As trees are drowned by rising beaver impoundments, they become an ideal habitat for woodpeckers, which carve cavities that may be later used by other bird species. Beaver-caused ice thawing in northern latitudes allows Canada geese to nest earlier.
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Other semi-aquatic mammals, such as water voles, muskrats, minks, and otters, will shelter in beaver lodges. Beaver modifications to streams in Poland create habitats favorable to bat species that forage at the water surface and "prefer moderate vegetation clutter". Large herbivores, such as some deer species, benefit from beaver activity as they can access vegetation from fallen trees and ponds.
Behavior.
Beavers are mainly nocturnal and crepuscular, and spend the daytime in their shelters. In northern latitudes, beaver activity is decoupled from the 24-hour cycle during the winter, and may last as long as 29 hours. They do not hibernate during winter, and spend much of their time in their lodges.
Family life.
The core of beaver social organization is the family, which is composed of an adult male and an adult female in a monogamous pair and their offspring. Beaver families can have as many as ten members; groups about this size require multiple lodges. Mutual grooming and play fighting maintain bonds between family members, and aggression between them is uncommon.
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Adult beavers mate with their partners, though partner replacement appears to be common. A beaver that loses its partner will wait for another one to come by. Estrus cycles begin in late December and peak in mid-January. Females may have two to four estrus cycles per season, each lasting 12–24 hours. The pair typically mate in the water and to a lesser extent in the lodge, for half a minute to three minutes.
Up to four young, or kits, are born in spring and summer, after a three or four-month gestation. Newborn beavers are precocial with a full fur coat, and can open their eyes within days of birth. Their mother is the primary caretaker, while their father maintains the territory. Older siblings from a previous litter also play a role.
After they are born, the kits spend their first one to two months in the lodge. Kits suckle for as long as three months, but can eat solid food within their second week and rely on their parents and older siblings to bring it to them. Eventually, beaver kits explore outside the lodge and forage on their own, but may follow an older relative and hold onto their backs. After their first year, young beavers help their families with construction. Beavers sexually mature around 1.5–3 years. They become independent at two years old, but remain with their parents for an extra year or more during times of food shortage, high population density, or drought.
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Territories and spacing.
Beavers typically disperse from their parental colonies during the spring or when the winter snow melts. They often travel less than , but long-distance dispersals are not uncommon when previous colonizers have already exploited local resources. Beavers are able to travel greater distances when free-flowing water is available. Individuals may meet their mates during the dispersal stage, and the pair travel together. It may take them weeks or months to reach their final destination; longer distances may require several years. Beavers establish and defend territories along the banks of their ponds, which may be in length.
Beavers mark their territories by constructing scent mounds made of mud and vegetation, scented with castoreum. Those with many territorial neighbors create more scent mounds. Scent marking increases in spring, during the dispersal of yearlings, to deter interlopers. Beavers are generally intolerant of intruders and fights may result in deep bites to the sides, rump, and tail. They exhibit a behavior known as the "dear enemy effect"; a territory-holder will investigate and become familiar with the scents of its neighbors and react more aggressively to the scents of strangers passing by. Beavers are also more tolerant of individuals that are their kin. They recognize them by using their keen sense of smell to detect differences in the composition of anal gland secretions. Anal gland secretion profiles are more similar among relatives than unrelated individuals.
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Communication.
Beavers within a family greet each other with whines. Kits will attract the attention of adults with mews, squeaks, and cries. Defensive beavers produce a hissing growl and gnash their teeth. Tail slaps, which involve an animal hitting the water surface with its tail, serve as alarm signals warning other beavers of a potential threat. An adult's tail slap is more successful in alerting others, who will escape into the lodge or deeper water. Juveniles have not yet learned the proper use of a tail slap, and hence are normally ignored. Eurasian beavers have been recorded using a territorial "stick display", which involves individuals holding up a stick and bouncing in shallow water.
Interactions with humans.
Beavers sometimes come into conflict with humans over land use; individual beavers may be labeled as "nuisance beavers". Beavers can damage crops, timber stocks, roads, ditches, gardens, and pastures via gnawing, eating, digging, and flooding. They occasionally attack humans and domestic pets, particularly when infected with rabies, in defense of their territory, or when they feel threatened. Some of these attacks have been fatal, including at least one human death. Beavers can spread giardiasis ('beaver fever') by infecting surface waters, though outbreaks are more commonly caused by human activity.
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Flow devices, like beaver pipes, are used to manage beaver flooding, while fencing and hardware cloth protect trees and shrubs from beaver damage. If necessary, hand tools, heavy equipment, or explosives are used to remove dams. Hunting, trapping, and relocation may be permitted as forms of population control and for removal of individuals. The governments of Argentina and Chile have authorized the trapping of invasive beavers in hopes of eliminating them. The ecological importance of beavers has led to cities like Seattle designing their parks and green spaces to accommodate the animals. The Martinez beavers became famous in the mid-2000s for their role in improving the ecosystem of Alhambra Creek in Martinez, California.
Zoos have displayed beavers since at least the 19th century, though not commonly. In captivity, beavers have been used for entertainment, fur harvesting, and for reintroduction into the wild. Captive beavers require access to water, substrate for digging, and artificial shelters. Archibald Stansfeld "Grey Owl" Belaney pioneered beaver conservation in the early 20th century. Belaney wrote several books, and was first to professionally film beavers in their environment. In 1931, he moved to a log cabin in Prince Albert National Park, where he was the "caretaker of park animals" and raised a beaver pair and their four offspring.
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Commercial use.
Beavers have been hunted, trapped, and exploited for their fur, meat, and castoreum. Since the animals typically stayed in one place, trappers could easily find them and could kill entire families in a lodge. Many pre-modern people mistakenly thought that castoreum was produced by the testicles or that the castor sacs of the beaver were its testicles, and females were hermaphrodites. Aesop's Fables describes beavers chewing off their testicles to preserve themselves from hunters, which is impossible because a beaver's testicles are internal. This myth persisted for centuries, and was corrected by French physician Guillaume Rondelet in the 1500s. Beavers have historically been hunted and captured using deadfalls, snares, nets, bows and arrows, spears, clubs, firearms, and leg-hold traps. Castoreum was used to lure the animals.
Castoreum was used for a variety of medical purposes; Pliny the Elder promoted it as a treatment for stomach problems, flatulence, seizures, sciatica, vertigo, and epilepsy. He stated it could stop hiccups when mixed with vinegar, toothaches if mixed with oil (by administering into the ear opening on the same side as the tooth), and could be used as an antivenom. The substance has traditionally been prescribed to treat hysteria in women, which was believed to have been caused by a "toxic" womb. Castoreum's properties have been credited to the accumulation of salicylic acid from willow and aspen trees in the beaver's diet, and has a physiological effect comparable to aspirin. Today, the medical use of castoreum has declined and is limited mainly to homeopathy. The substance is also used as an ingredient in perfumes and tinctures, and as a flavouring in food and drinks.
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