High levels of natal philopatry and no difference in reproductive success between philopatric and non-philopatric songbirds breeding in a native forests of east-central Argentina

Abstract

Philopatric birds have a number of advantages when breeding in familiar habitats, such as learning the locations of food, efficient movement throughout the breeding area, or effective escape from predators. However, few investigators have examined the possible effect of site familiarity on reproductive success, even less for Neotropical songbirds. We studied a breeding population of Masked Gnatcatchers (Polioptila dumicola) and Vermilion Flycatchers (Pyrocephalus rubinus), two south temperate songbirds, and examined the possible reproductive benefits of natal philopatry. In our population, 13.9% and 6.9% of breeding adults, respectively, for Masked Gnatcatchers and Vermilion Flycatchers, were philopatric. We found no difference in the breeding success between philopatric and non-philopatric individuals. Our results showed higher levels of philopatry for both species than previously reported for other songbirds. Because the remnants of native forests in our study area were located within a matrix of highly disturbed habitats, these intermediate-to-high values of natal philopatry could be linked to the structural characteristics of the forest that may force birds to use the few suitable forest patches available in the area.