Daily patterns of activity of passerine birds in a Magellanic sub-Antarctic forest at Omora Park (55A°S), Cape Horn Biosphere Reserve, Chile

Ecosystems in the sub-Antarctic region can be subjected to extreme weather conditions year-round. Little data exist that show any relationship between climatic variables and activity patterns of passerine birds, despite the fact that weather patterns can have a dramatic influence on the foraging strategies of these birds in different seasons. Passerine birds must balance the risk of starvation and the risk of predation in accordance with variation in environmental variables. The goal of this study was to determine the relationship of season, habitat type and weather patterns with the daily activity patterns of three diurnal passerine bird species from different trophic guilds. Unlike most low-latitude passerine species, the three passerine bird species in Omora Park on Navarino Island do not show strict adherence to a bimodal activity pattern; instead, these birds show a variety of activity patterns throughout the year that differ by trophic guild and habitat type. These modifications in activity patterns may be an adaptation to minimize the risk of predation and starvation in the face of temperature-dependent food availability.