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Dryad

Delayed dispersal in splendid fairywrens

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Jun 05, 2024 version files 24.87 KB

Abstract

Delayed dispersal is a critical first step in the formation of both cooperative breeding and family-living groups. However, disentangling the multiple, potentially co-occurring factors that influence the dispersal of young individuals is often difficult and can require multiple data sources. We combine data from a long-term mark-recapture study and field experiments to address the patterns, fitness consequences, and proximate causes of delayed dispersal in the splendid fairywren (Malurus splendens melanotus). This species is a cooperative breeder, with males remaining as helpers more often for more years and settling closer to their natal territories than females. We found that birds who were helpers in one or more years had greater first-year nest success, and the number of years spent helping had a positive impact on survival. By experimentally producing breeding vacancies for young males, we tested if male-biased sex ratio and breeding opportunities constrained dispersal in this system. Only half of the vacancies created were filled, and dispersal took, on average, approximately three days. These findings illustrate that ecological constraints, benefits-of-philopatry, and life history benefits may all be acting within the same system to shape dispersal patterns.