Mammal Diversity and Conservation in the Selva Lacandona, Chiapas, Mexico

The Selva Lacandona region of Chiapas, Mexico, has high biodiversity, represents the last large portion of tropical rainforest in México, and faces imminent destruction. Through fieldwork and literature searches I found a total of 112 mammal species (including 17 Middle-American endemics) on the Lacandona's 331,200 ha Montes Azules Biosphere Reserve. This inventory plus those from eight additional Neotropical localities show local mammal species richness in the Neotropics to be in the range of 70–116 species. Richness is primarily correlated with the amount of annual rainfall, but within rainforest areas species richness is probably not correlated with rainfall, latitude, altitude, or area size. Rather, above a certain limit of rainfall and below a critical level of latitude and altitude, mammal species richness seem to reach an asymptotic maximum. Areas covered with tropical rainforest and with a well-known, relatively intact fauna have about 112–116 mammal species. In the Montes Azules Reserve most mammals (57%) are bats. The most heavily occupied feeding guilds are frugivores/herbivores and insectivores/omnivores. Large species and carnivores appear most vulnerable to local extinction. Montes Azules (and thus the Selva Lacandona) is especially noteworthy because (1) it contains a greater proportion of species facing conservation problems than expected from a random draw of Mexican mammals; (2) it is probably the most diverse ecosystem in Mexico; (3) many species sustain their only Mexican populations in this area; and (4) it is the largest remnant of tropical rainforest in Mexico and is part of the largest expanse of that vegetation type in Central America.