Providing longer post-fledging periods increases offspring survival at the expense of future fecundity.

Abstract

The cost of reproduction is a key concept in life-history trade-offs. However, our understanding of the reproductive costs is biased towards measures of reproductive effort obtained before offspring independence. During the post-fledging dependence period (PFDP), it is well known that parents feed and protect their offspring. However, the effort devoted to this reproductive activity has never been considered in the context of of the costs of reproduction. Moreover, the potential fitness benefits and costs for offspring and parents, respectively, of the duration of the PFDP are largely unknown. We estimated the duration of the PFDP over 5 years using wild common kestrels (Falco tinnunculus) and studied its association with survival probability and future parental reproductive performance. Our results show that longer PFDPs increase the survival probability of fledglings, probably due to the benefits obtained from parental care. In addition, we found that providing longer PFDPs was associated with reduced clutch sizes but not the number of fledglings in the subsequent breeding season in males. We suggest that increased parental expenditures on offspring during the PFDP may represent a potential cost of reproduction in breeding males.