Download or read book Demographic and Fitness Consequences of Delayed Dispersal in the Cooperatively Breeding Acorn Woodpecker written by Justyn T. Stahl and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Cooperative breeding in birds occurs when more than two individuals provide care for a single nest. In many species, the additional adults present are offspring from a previous year who have delayed dispersal, and provision young who are non-descendant kin. Delaying dispersal and age of first breeding can influence the demography and fitness of individuals, but the fitness and demographic consequences of helping behavior are poorly understood. Using long-term data (1972-2004), I examined the demographic and fitness consequences of helping behavior in acorn woodpeckers Melanerpes formicivorus. Using a multi-state capture-mark-recapture framework, I found that the apparent survival of breeders was higher than helpers, and the survival of males was higher than females. Juveniles were much more likely to become helpers rather than breeders following fledging, and helpers were more likely to remain helpers rather than becoming a breeder. Both survival and transition rates varied annually and were positively influenced by the acorn crop. For fitness estimation, I focused only on reproductive females who were banded as juveniles. Although helpers began reproduction significantly later and lived significantly longer than breeders, there was no significant difference in lifetime reproductive success or individual fitness between the two groups. However, birds that successfully bred at age 1 without helping had a significantly higher fitness than those who helped and successfully bred at age 2 or older. My results suggest that delayed dispersal and reproduction in the acorn woodpecker lead to a loss of fitness when conditions are favorable for successful reproduction. However, if constraints in the environment prevent an individual from breeding at age 1, helping is a viable option until reproduction is possible.