Rarity in Neotropical Bats: Correlations with Phylogeny, Diet, and Body Mass

Bats are an important component of tropical faunas, both in terms of number of species and total biomass. Very little information, however, is available on the status and conservation of this diverse group. To contribute to the solution of this problem, rarity among Neotropical bats was analyzed using a set of 150 species. Rarity was quantified by local abundance and area of distributional range and by a combined index of rarity created by compounding these two variables. Nested analyses of variance showed local abundance to be more variable among genera than at any other taxonomic level, and area of distribution to be more variable among species. No significant correlation with body mass was found for local abundance or for area of distribution. Similarly, no correlation was found between distribution and abundance. Local abundance, but not area of distribution, varied significantly among taxonomic and trophic categories. At the local level, bats of the family Molossidae tend to be less abundant than other species. Bats that feed on plant parts or products (fruit, nectar, and pollen) are more abundant than insectivores and carnivores. The distribution of species among Rabinowitz' categories of rarity varied among taxonomic and trophic groups. The classification of rarity and the combined index of rarity introduced here can be used as guidelines for the identification of vulnerable species.