Was carried out a study on the wildlife of the Sierra del AjusDivisico and Sierra Nevada, localized into the Transmexican Volcanic Belt, in the eastern portion of the Southern limit of the Cuenca de Mexico. The high biological richness of this area, that surrounds the Mexico City, one of the largest metropolis in the world, has survived during decades the urbanization impacts on the forest areas, the forest resources use, pollution, hunting, forest fires, ad cattle raising. Despite this, are unknown many of the factors that regulate the dynamics of the ecosystems in this region In relation to the wildlife, the lack of information is by far more evident. Topics such as species diversity, ecological interactions, organism’s ecosystem function, and stress conditions, have received scarce attention. This research included field work and also bibliographic review, in order of estimating the species richness of mammals, birds, reptiles, and amphibians, their ecological relationships, and the consequences of habitat modification, because of the human activities.