AVIAN COMMUNITY STRUCTURE : LAND USE IMPACTS ON BETA DIVERSITY AND SPECIES RICHNESS IN THREE DISTINCT HABITATS ON MOOREA , FRENCH POLYNESIA

Conservation efforts can be improved by considering the biological diversity in a region. Diversity, commonly divided into α, β, and γ types, describes the structure of one or more communities. β diversity is particularly helpful, as it allows for comparative analyses – such as comparing community structure in regions with active conservation efforts versus regions without those efforts. The island of Moorea, French Polynesia is a good model system for examining β diversity between different habitats, as most of the island falls within one of three habitat categories: forest, agricultural, and urban. The unusually low rate of avian endemism on Moorea is further motivation to examine the factors that shape bird community structure on that island. For this study, richness and abundance data for the birds of Moorea were collected at 12 sites in each habitat using a point-count method. β diversity was computed for each habitat, applying five widely-used diversity indices – Jaccard, Chao, Bray-Curtis, Manhattan, and Euclidean. The relative effect of native and invasive species on β diversity was examined by further subdividing the data to distinguish between native and invasive species and repeating the β diversity analysis for the Manhattan and Euclidean indices, which accommodate such a distinction. The β diversity results were supplemented by analyzing the α diversity of the communities, and by examining how species richness has changed over the past nine years. Five hypotheses were tested: (1) habitats have unique communities, (2) α and β diversity depend on habitat type, (3) β diversity is highest in the forest and lowest in urban areas, (4) invasive species account for most of the observed β diversity, and (5) species richness, percent native species, and number of endemic species rose from 2004 to 2013. Hypotheses (1), (2), and (4) were supported by the study, while (3) and (5) were not. Results suggest that conservation work should be guided by research into the roles native and invasive species play in determining the β diversity of habitats under consideration for conservation.