Environmental predictability and remating in European blackbirds |
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Authors: | Desrochers Andre; Magrath Robert D |
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Institution: | Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
Edward Grey Institute of Field Ornithology, Department of Zoology, University of Oxford South Parks Road, Oxford OX1 3 PS, UK |
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Abstract: | We studied mate and site fidelity between years in an Englishpopulation of blackbirds (Turdus merula) from 1985 to 1991.Divorce was observed in 32% of 183 cases where mates had survivedfrom the previous breeding season. After divorces, females tendedto nest farther from their original site than males did, butthere was no sex difference in distance moved after the deathof a mate. The mean annual fledgling production of 60 m x 60m breeding sites was statistically repeatable among years, evenafter accounting for possible differences in reproductive performanceamong site-tenacious individuals. Divorce rates were greatestin low-quality sites. We found no annual fitness cost associatedwith mating with an unfamiliar bird. However, breeding in anew site cost on average one fledgling per year. |
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Keywords: | Turdus merula breeding dispersal site tenacity divorce territory quality experience |
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