Home‐range Size of an Andean Bird: Assessing the Role of Physical Condition

Because space-use patterns are a key aspect of the ecology and distribution of species, identifying factors associated with variation in size of territories and home ranges has been central to studies on population ecology. Space use might vary in response to extrinsic factors like habitat quality and to intrinsic factors like physical condition and individual aggressiveness. However, the role of these factors has been poorly documented in the tropics, particularly in high-elevation bird species. We report the home-range size of a Neotropical Andean bird, the gray-browed brush finch (Arremon assimilis), and evaluate the role of physical condition in explaining variation in home-range size among individuals. We performed spot mapping to estimate the home ranges of 14 territorial males in Bogota, Colombia, using minimum convex polygons (MCP) and 95% kernel density estimators (KDE). The mean home-range size estimated for the 100% MCP was 0.522 +/- 0.305 ha (range = 0.15-1.18 ha), whereas the 95% KDE estimation was 0.504 +/- 0.471 ha (range = 0.13-1.88). We calculated the real mass index of each bird as a proxy of physical condition to assess whether individuals in better physical condition had larger home ranges. Because we found no relation between our estimations of physical condition and home-range size, we conclude that space use in this species might depend more on ecological factors such as habitat quality or neighbor density than on individual traits. in French is available with online material.