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Nestling provisioning in polygynous great reed warblers (Acrocephalus arundinaceus): do males bring larger prey to compensate for fewer nest visits?

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Author

Summary, in English

Most studies of social polygyny in birds have examined male provisioning on the basis of the number of feeding visits. This may be misleading if males compensate for infrequent visits by bringing larger prey at each visit. We investigated nestling provisioning in the socially polygynous great reed warbler, Acrocephalus arundinaceus, in south Central Sweden in 1996-1997. We collected data on rare of feeding visits, prey size and the amount of biomass delivered by males and females. Males had lower rates of feeding visits and provided smaller prey to nestlings in secondary than in monogamous and primary nests. Secondary females had higher rates of feeding visits and brought larger prey than monogamous and primary females. These results confirm that secondary females face a potential cost of polygyny through a lower rate of male feeding, and that this cost was reinforced by the significantly lower male provisioning rate (biomass h(-1)) at secondary nests. Secondary females compensated for the lack of male assistance by increasing their rate of feeding and bringing larger prey. As a result, offspring in nests of secondary females received as much food as did those in nests of primary females. Prey load size increased with the parent's proportion of feeding visits, suggesting that parents use different feeding strategies depending on their amount of responsibility for nestling provisioning. We suggest that parents which take the main responsibility for nestling feeding have to forage further away from the nest, and based on optimal-foraging theory, they should then on average bring larger prey to their nest.

Publishing year

2000

Language

English

Pages

213-219

Publication/Series

Behavioral Ecology and Sociobiology

Volume

47

Issue

4

Document type

Journal article

Publisher

Springer

Topic

  • Biological Sciences

Status

Published

Project

  • Long-term study of great reed warblers

Research group

  • Molecular Ecology and Evolution Lab

ISBN/ISSN/Other

  • ISSN: 1432-0762