SUMMARY
Studies on diversity of animal communities allow determination of their species richness and composition. This information is particularly relevant to establish sound conservation programs in biosphere reserves, where human activities should be focused on the sustainable use of natural resources and ensure biodiversity protection. This study estimated the diversity and species richness and determined the species composition and activity patterns of medium- and large-sized terrestrial mammals in the Los Tuxtlas Biosphere Reserve (LTBR) located in Veracruz, Mexico. We set 18 camera traps to record medium and large-sized terrestrial mammals from August 2016 to January 2017. We calculated the trapping rate, guilds, and activity patterns of species. Diversity was estimated with Hill numbers. We compared our estimates with other studies in tropical forest in Mexico. We obtained 308 independent captures of 13 species; Cuniculus paca and Dasyprocta mexicana were the species with the highest trapping rate. Order-0, order-1, and order-2 diversity values were 13.99, 6.50, and 4.75 effective species, respectively, which ranks LTBR the fourth-most diverse reserve of medium- and large-sized terrestrial mammals compared to six other tropical rainforest sites in southern Mexico. We recorded mammals representing five trophic guilds, of which frugivore-folivores (five species) and omnivores (three species) ranked highest. All recorded species were primarily nocturnal (six species) or diurnal (six species). Tamandua mexicana, Leopardus pardalis, L. wiedii, and Eira barbara are listed as endangered in the Mexican Official Standard Norm NOM-059-2019, and L. wiedii is listed as near threatened in the IUCN Red List of Threatened Species. We were able to record 40.6 % of the terrestrial mammal species known to inhabit the LTBR. The absence of large-sized species such as large predators and herbivores was notable. Comparison of medium and large-sized mammal diversity of camera trapping studies in Mexico show that landscape degradation is impoverishing terrestrial mammal communities.