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| <p>EFFECTS OF TERRITORY ENHANCEMENT ON ADULT FEEDING RATES AND FREQUENCY OF DOUBLE BROODING IN THE EASTERN BLUEBIRD (<em>SIALIA SIALIS</em>), C.M. ANHALT AND M.Z. KHAN*, Ripon College – Ripon, Biology Department, Ripon, WI 54971, HYPERLINK "mailto:khanm@ripon.edu" khanm@ripon.edu</p> | |
| <p> Some avian species raise two consecutive broods in a given breeding season. A pair’s decision to double brood is likely influenced by resource availability on their territory. We tested the hypothesis that mealworm supplements will increase the probability of double brooding in the eastern bluebird (<em>Sialia sialis</em>). Nests were supplemented with 65kJ of mealworms upon nest completion and remained supplemented until the brood fledged. Feeding rates at supplemented and control nests were measured to determine if mealworms were fed to nestlings. Length of incubation period and nestling period were measured with daily nest box checks. Nestling mass was measured daily from hatching to 13 days after hatch to compare growth curves between treatments Double brooding was defined as the presence of a second clutch in a previously successful nest box. Comparisons were made with one-tailed t-tests at a 0.05 alpha level. Feeding rates at supplemented nests were significantly greater than at control nests demonstrating that mealworm supplements were effective. Incubation period was unaffected by treatment. The nestling period at supplemented nests was significantly shorter (<em>x±</em>SE, 19.17<em>±</em>0.31) than at control nests (19.75<em>±</em>0.31). Nestling growth reached an asymptote 10 days after hatch, and growth curves of nestlings at supplemented nests were not different than at control nests Average nestling mass (10-13 days after hatch) was slightly greater at supplemented nests (26.54<em>±</em>0.28) compared to control nests (23.68<em>±</em>1.31), t0.05,17 = 2.14, p = 0.02 (one-tailed). Double brooding was observed in 71% percent (5/7) of supplemented nests and 28% percent (2/7) of control nests. However this difference was not statistically significant. Overall supplements had no effect on double brooding but the shortened nestling period at supplemented nests acts a possible cue influencing a pair’s decision to double brood. Furthermore increased nestling mass may have an effect on the overall viability of the brood in the long term. </p> | |
| <p>C.A. Anhalt was supported by Grant-In-Aid of Research from Sigma Xi (ID G20083150843) and Wisconsin Society of Ornithology.</p> | |
| <p>M.Z. Khan was supported by a FaCE grant from the Associated Colleges of the Midwest.</p> | |
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