Dispersal entails costs and might have to be traded off against other life-history traits. Dispersing and philopatric individuals may thus exhibit alternative life-history strategies. Importantly, these differences could also partly be modulated by environmental variation. Our previous results in a patchy population of a small passerine, the collared flycatcher, suggest that, as breeding density, a proxy of habitat quality, decreases, dispersing individuals invest less in reproduction but maintain a stable oxidative balance, whereas philopatric individuals maintain a high reproductive investment at the expense of increased oxidative stress. In this study, we aimed at experimentally testing whether these observed differences between dispersing and philopatric individuals across a habitat quality gradient were due to food availability, a major component of habitat quality in this system. We provided additional food for the parents to use during the nestling rearing period and we measured subsequent parental reproductive effort (through provisioning rate, adult body mass, and plasmatic markers of oxidative balance) and reproductive output. Density-dependent differences between dispersing and philopatric parents in body mass and fledging success were observed in control nests but not in supplemented nests. However, density-dependent differences in oxidative state were not altered by the supplementation. Altogether, our results support our hypothesis that food availability is responsible for some of the density-dependent differences observed in our population between dispersing and philopatric individuals but other mechanisms are also at play. Our study further emphasizes the need to account for environmental variation when studying the association between dispersal and other traits.
Bibliographical noteThis work was supported by the French National Center for Scientific Research (PICS France-Switzerland to B.D.); the French Ministry of Research (PhD fellowship to C.R.); the L’Oréal Foundation-UNESCO “For Women in Science” program (fellowship to C.R.); the Région Rhône-Alpes (Explora’doc mobility grant to C.R.); the Rectors’ Conference of the Swiss Universities (grant to C.R.) and the Fondation pour l'Université de Lausanne (grant to C.R.).
- parental care
- breeding density
- habitat quality
- oxidative stress
- reproductive output
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Data from: Food availability modulates differences in parental effort between dispersing and philopatric birds
Récapet, C. (Creator), Bize, P. (Creator), Doligez, B. (Creator) & Paton, G. (Data Manager), Dryad Digital Repository, 19 Jan 2017