Dynamics of Bird Communities in the Chihuahuan Desert, New Mexico

Abstract

To say that communities of organisms are dynamic entities is a truism. Communities of birds-in common with those of other organisms-are in a perpetual state of flux, changing from day to day, season to season, and year to year in a number of properties: overall abundance, species composition, relative abundance of species, and impact on other components of the ecosystem, among others. It is also obvious that a fruitful approach for ecologists seeking to understand factors influencing properties of bird communities might be to follow different ones through time, comparing different properties as they change, while simultaneously following potential causative factors such as climate and food supply. In spite of the logic arguing for such an approach we can find little evidence of attempts to employ it, though many investigations have been made of both short-term and long-term changes in individual species populations (the more significant of these are summarized by Lack 1966). We know of only two published studies of temporal changes in a grassland or desert bird community (Finzel 1964, Webster 1964). Recent, largely unpublished studies made in connection with the International Biological Program will be discussed below.