Translator Disclaimer
1 May 2010 A Model-Selection Approach to Predicting Whether Florida Scrub-Jays Delay Breeding
David R. Breininger, Eric D. Stolen, Geoffrey M. Carter, Donna M. Oddy, Danny K. Hunt
Author Affiliations +

The choices animals make in dispersal are of interest because they describe in part how populations adjust to a changing environment. We investigated which factors influence whether adult Florida Scrub-Jays delay breeding within their natal territories or disperse to breed. Factors considered included those pertaining to individuals (sex, age, parents), breeding opportunities (territory densities, deaths of breeders, potential mates, competitors [nonbreeders of the same sex]), and habitat (quality, suburb versus conservation area). We compared models that included each of these factors or combinations of them. We used nomograms to evaluate effect sizes and post hoc analyses to explore nonlinear effects of variables and their relative importance. Models that included only one or a few variables had little support. Models with the greatest support included parents, deaths of breeders, age, sex, and potential mates. Increased deaths of breeders greatly decreased the probabilities of delayed dispersal. Dispersal was most delayed if both parents or just the father remained breeders. One-year-olds and males delayed dispersal more than older nonbreeders and females. Post hoc analyses revealed that the probability of delayed breeding was lowest at intermediate densities of potential mates, suggesting that at low densities Florida Scrub-Jays delay breeding because they can't find mates and at high densities because of high competition to fill vacancies left by breeders' deaths. Our results are important because they suggest that no single factor explains delayed breeding adequately and that factors important for population recovery and minimizing extinction risk are also important for maintaining cooperative breeding behavior.

© 2010 by The Cooper Ornithological Society. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press's Rights and Permissions website,
David R. Breininger, Eric D. Stolen, Geoffrey M. Carter, Donna M. Oddy, and Danny K. Hunt "A Model-Selection Approach to Predicting Whether Florida Scrub-Jays Delay Breeding," The Condor 112(2), 378-389, (1 May 2010).
Received: 24 August 2009; Accepted: 1 December 2009; Published: 1 May 2010

Get copyright permission
Back to Top