The Influence of Food Supply on Local Density and Diversity of Sparrows

Abstract

A long—term study of sparrows in an arid oak woodland in southeastern Arizona demonstrated that local population density of sparrows is independent of local seed abundance during years of moderate to high seed production. Experimental manipulation of the abundance and size distribution of seeds during 2 yr of moderate seed production had no discernible influence on the local abundance or diversity of sparrows. These experimental results support the hypothesis, based on previous nonexperimental observations, that sparrow populations in this habitat are locally food limited only during infrequent years of very low seed productions.