An Analysis of New World Mangrove Avifaunas Diversity, Endemism, and Conservation

Abstract

Most bird species inhabiting mangroves are considered visitors to the habitat. However, some species feed or reproduce almost exclusively in mangroves. If most are visitors, then the question arises as to whether bird communities characteristic of mangroves actually exist. Similarly, the influence of adjacent vegetation types on avifaunal composition in mangroves remains unassessed. In this study, I address these questions, providing fundamental information regarding the avifaunas of New World mangroves. I surveyed avifaunas at nine sites in Mexico and El Salvador. Mangroves were traversed principally by canoe, and on foot when possible. For each area, species presence, type of vegetation, and use of mangroves for perching, nesting, rearing young, or feeding were recorded. Three principal methods were used to complete inventories of the study sites: visual sightings, mist netting, and taperecordings of bird vocalizations. Inventory completeness was assessed using species accumulation curves and inferential analyses. I assembled species lists for another 32 localities (29 from the New World and three from Gambia, Malaysia, and Australia from the literature. I compiled a matrix of occurrences of 923 bird species at 42 mangrove sites. I carried out an analysis of similarity to establish differences among sites based on 672 resident species. In addition, I analyzed the importance of mangroves for birds as feeding, roosting, and nesting habitat. I conclude that New World mangrove avifaunas are markedly distinct from those of Gambia, Malaysia, and Australia mangroves. The New World mangrove avifauna clustered in two major groups: North and Central America, and South America. Most of the 715 bird species that inhabit 39 New World mangrove sites used forested areas within the mangrove ecosystem, and fed principally on invertebrates, but few of them nest exclusively in mangroves. However, for some species of parrots (e.g., Aratinga spp., and Brotogeris spp.) this habitat may be crucial for their reproduction. In the New World, about 2 1 0 protected and proposed coastal areas exist within the general distribution of mangroves, mangrove sites along the Pacific slope of South America and Mexico are in critical need of protection.