干旱区生态环境知识资源中心

We studied seasonal variation in a community of birds inhabiting a forest-steppe ecotone of north Patagonia. We analyzed changes in species richness, species composition and total abundance, and, at the species level, we evaluated differences in breeding and molting seasonality. The bird assemblage showed a low seasonal variation in richness and total abundance, but a great change in species composition between spring-summer and fall-winter. The change in species composition did not lead to changes in richness and total abundance, due to the presence of abundant species that visit the area in different seasons. At the species level, resident birds and short distance migrants tended to begin breeding earlier than long distance migrants, and those bird species began to molt body and flight feathers after breeding. Therefore, we found a low overlap between these two energetically demanding activities. Elaenia albiceps, the only long-distance migrant species, did not molt body and flight feathers in our study area. Our results highlight the importance of bird movements in response to seasonal variations in the availability of resources, which promote migration or local displacements of birds.