Avifauna Richness on the California Channel Islands

Abstract

Variation is analyzed in the numbers of land bird species breeding on 8 Channel Islands off the coast of S California [USA]. Variation in maximum island elevation and numbers of native plant species are principal predictors of avian diversity. Island area is also highly correlated with number of bird species. A comparison is made with an earlier analysis of avian diversity on the California Islands, which include the Channel Islands plus 8 more off the coast of Baja California [Mexico]. In this geographically and climatically more heterogeneous collection, numbers of plant species alone is most significant in explaining variation in number of bird species. Elevation and plant diversity are less highly correlated here owing to more arid conditions. Habitat diversity rather than elevation or area per se appears to be the primary factor accounting for avian diversity on the California Islands.