PARENT SESSION
Oral Session #64: Avian Ecology. Presiding: P. Warren.
Thursday, August 9, 2001. 8:00 AM to 12:00 PM. Hall of Ideas I.
Spatial dynamics of bird communities in a "resource-mosaic" landscape .
ESTADES, CRISTIAN1,2, TEMPLE, STANLEY1, 1 2
ABSTRACT- Models that describe the use of patchy landscapes by animals have often used a single descriptor for the quality of each patch. However, animals likely assess habitat quality by looking at the distribution of the different resources they depend on. Because the latter are not necessarily spatially correlated, a model that uses the independent distribution of a few key resources may describe the distribution of animals better than a simple "patch" model. The landscape in the Maule region of Central Chile is characterized by a severely fragmented native vegetation immersed in a matrix of exotic pine plantations. In a 10,000-ha area in that region we studied the spatial distribution of insectivorous forest birds in relation to the distribution of food resources and nest sites in three different seasons (Spring, Summer and Winter) over a two year period. Cavity nesters aggregated in native forest fragments during the breeding season but as soon as cavities were no longer a limiting factor these birds moved to forage into the adjacent pine plantations mostly in the form of mixed flocks. Open-cup nesters were more evenly distributed in the landscape and tended to be associated with the structure and composition of the understory and the abundance of food resources. Results indicate that the "resource-mosaic" model is an appropriate approach to modelling the distribution of birds in the studied landscape, particularly because it provides a mechanistic tool for accounting for differences in distribution between species and between seasons.
KEY WORDS: birds, spatial dynamics, patchy landscapes, resource distribution