| Conservation biologists use many methods to increase the population size of threatened and endangered birds. In particular, nestling transfers have been used to increase the probability of survival mainly in precocial species. However, such manipulations of altricial species have rarely been used solely for conservation purposes. The goal of this study was to examine the potential for nestling transfers to enhance the population productivity of altricial birds using red-winged blackbirds (Agelaius phoeniceus ) as a model system. The protocol used prior knowledge of the relationship between reproductive success and family size to transfer nestlings from situations of low to high survival. Many altricial birds generate brood hierarchies among their offspring by hatching their eggs asynchronously. First-hatched "core" progeny enjoy higher average survival and growth than later-hatched "marginal" nestlings, particularly in larger broods. (Abstract shortened by UMI.). |
