BIRD ASSEMBLAGES IN THE SOUTHERMOST FOREST OF THE WORLD: METHODOLOGICAL VARIATIONS FOR DETERMINING SPECIES COMPOSITION

CHRISTOPHER B. ANDERSON; RICARDO ROZZI

ANALES DEL INSTITUTO DE LA PATAGONIA

Universidad de Magallanes

Año: 2000 vol. 28 p. 89 - 100

0718-6932

During the austral summer of 2000 we studied the avifauna in coastal forest of Magallanes, Chile at two study sites: Peninsula Antonio Varas (52ºS) and Isla Navarino (55ºS). For each of these sites we investigated the species composition of the woodland bird assemblage through mist-nets, point-count station along transects, and all observed species, including observations outside of the transects and/or mist-nets. Then, we compared the results obtained by each method, as well as with species list obtained from bibliographic sources. Our species list correspond to 95% of bibliographic accounts. At Navarino we detected the presence of two species which were previously unreported: Colorhamphus parvirostris and Sphanoides galeritus. Transect and mist-net methodologies accounted for just part of the bird species assemblage, but addressed the important variation in abundance among species. Compared to avian assemblages recorder in Chilean forests at lower latitudes, the Magellan area contains fewer species. This confirms previous statements about the decrease in bird species with increasing latitud along these forests. There are also some major changes in relative abundance of species. For example, the hummingbird S. galeritus is the most abundant species in forest at Chiloé, but in Magallanes it was never greater than 5%. Other major species (e.g. Elaenia albiceps, Turdus falcklandii, Aphrastura spinicauda, and Phrygilus patagonicus) actually remain very similar as compared to Chiloé. We also compared bird assemblages of three types of habitats: forest interior, forest border, and open areas. These last two habitat type hosted greater abundance and species richness, including birds that are characteristics of forest interior habitats. These results needs to be carefully interpreted at the landscape level, because area opened by human activity in Magallanes are still embedded in a region that conserves large expanses of primary forest.