Implications of adult sex ratios for natal dispersal in a cooperative breeder

Speelman, Frigg Janne Daan, Borger, Mirjam J., Hammers, Martijn, Van Eerden, Arne O. K., Richardson, David S. ORCID: https://orcid.org/0000-0001-7226-9074, Burke, Terence, Dugdale, Hannah L. and Komdeur, Jan (2024) Implications of adult sex ratios for natal dispersal in a cooperative breeder. Animal Behaviour, 208. pp. 19-29. ISSN 0003-3472

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Abstract

In cooperatively breeding species, sexually mature individuals may delay natal dispersal and become subordinates, helping a dominant pair raise offspring. To understand how cooperative breeding evolved, it is important to determine the mechanisms leading to delayed dispersal. Adult sex ratio (ASR) variation may affect dispersal by limiting breeding vacancies available to the more abundant sex, and cooperative breeders often have a more biased ASR than noncooperative breeders. However, no studies of cooperative breeders have related ASR at both the local and population level with dispersal. Using the long-term Seychelles warbler, Acrocephalus sechellensis, data set, we tested the influence of population-wide and local ASR, and density, on natal dispersal of yearlings. Our ASR - density hypothesis predicts that the probability of natal dispersal is lower when the ASR is biased towards the sex of the focal individual, but only when the population density is high. Dispersal was associated with population density and population-wide ASR in males, but not in females; males were more likely to delay dispersal when ASR was male biased and density was high. Our findings illustrate a complex association between demographic factors and cooperative breeding and suggest that individuals alter their dispersal behaviour in response to the demographic composition of the population.

Item Type: Article
Faculty \ School: Faculty of Science > School of Biological Sciences
UEA Research Groups: Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation
Faculty of Science > Research Groups > Organisms and the Environment
Depositing User: LivePure Connector
Date Deposited: 03 Jan 2024 03:19
Last Modified: 03 Jan 2024 03:19
URI: https://ueaeprints.uea.ac.uk/id/eprint/94054
DOI: 10.1016/j.anbehav.2023.11.010

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