Reintroduction of songbirds from captivity: the case of the Great-billed Seed-finch (Sporophila maximiliani) in Brazil

Abstract

Ex situ breeding programs are a relevant strategy for recovering populations that are threatened in the wild. Thus, it is important to evaluate how different reintroduction strategies can affect population establishment, dynamics, survival, and local persistence. Herein, we use the Great-billed Seed-finch (Sporophila maximiliani), a songbird threatened with extinction in most Brazilian biomes, as an example. To identify scenarios that could result in viable populations in nature, we considered an introduction successful when the chance of surviving for 100 years was > 90%. Knowing the distribution of the captive populations, we also investigated where reintroductions should be promoted, considering the fragmented status of the natural vegetation and human pressures along the original southern range of S. maximiliani. We modeled the population viability under four different release schemes: one single area versus three different areas and, for each scheme, with or without the supplementation of individuals. The reintroductions would be successful if a minimum of 24 individuals were released in one single area or in three different areas, both with supplementation of four pairs per area over 5 years. However, few regions were appropriate for reintroduction from captivity, such as the central part of the Cerrado and the Atlantic Forest in the species distribution range. Specifically, areas such as veredas (palm swamps) should be target sites for reintroductions since the species is primarily common in these unique ecosystems. Our data indicated that any reintroduction needs monitoring, and individuals should be tracked to evaluate their effective establishment in the release areas.