THE INFLUENCE OF HABITAT STRUCTURE UPON DIVERSITY AND EVENNESS OF ABUNDANCE

摘要

This study examined the relationship between habitat heterogeneity and species diversity in a transitional zone between temperate and tropical America. Additionally, the relationship between habitat heterogeneity and evenness of abundance (EA) was examined, as measured by both abundance and flock size. Sampling of avian community diversity, as well as flock size and abundance of three sympatric Neotropical species with different breeding strategies (Green Jay Cyanocorax yncas, Groove-billed Ani Crotophaga sulcirostris and Plain Chachalaca Ortalis vetula) took place along the Rio Grande River in southern Texas. Sampling occurred during nine months of an annual cycle, at four different habitats representing different degrees of heterogeneity. Diversity and habitat heterogeneity exhibited the typical positive relationship. The three species in this study varied in abundance at different sites due to different microhabitat preferences. Flock sizes of the three species became more similar with increasing habitat heterogeneity due to more microhabitats within a mosaic selected by the suite of species.