Abstract

In southern Chile, the most diverse forest ecosystems are located between 36 degrees and 40 degrees S, in the same areas where agriculture and industrial forestry are concentrated. We studied bird assemblages in Bosque Pehuen Park (39 degrees 25'S), along a human disturbance gradient from early successional forest mixed with grasslands to barely disturbed old-growth forest. We surveyed birds across all of the disturbance gradients at 18 points from 860 to 1260 m a.s.l. using point-count methods. Each point was surveyed five times per year, during the Austral summer of 2015 and 2016. Our results confirmed that there is a group of forest birds strongly related to old-growth forest, while others were characteristic of open areas. Secondary forests shared bird species with both old-growth forests and disturbed areas, and presented lower abundance of forest bird specialists. The old-growth forest bird community proved to be small and was dominated by Thorn-tailed Rayadito (Aphrastura spinicauda, Furnariidae) and White-crested Elaenia (Elaenia albiceps, Tyrannidae). Most studies in this region have taken place in secondary forests, which are characterized by a lower presence of specialists and the inclusion of birds from open areas. Here, we provide a reference bird community for Andean forests, and we argue that bird communities in secondary forests are not a good control to analyze the effects of human disturbances. We emphasize the need to conserve the last remnants of the old-growth forest found in these regions.