Mammal diversity in Chile, as in other parts of temperate South America, is low. Severe climatic conditions associated with Pleistocene glacial movements in the Andes may have had a strong impact in reducing the diversity of temperate mammal faunas in South America. Major faunal extinctions also occurred in at the end of the Pleistocene in both South America and North America, and these extinctions have been associated with the arrival of early man.
Many ecological niches in temperate South America appear to be incompletely occupied by mammals in comparison with North America. Chile has 99 native terrestrial mammal species, 64 of which occur within the hotspot region. Five genera are endemic. The largest single group is the Rodentia (60%). Next in abundance are the Carnivora with 14%, and the Chiroptera (bats) with 10%. Few large mammal species exist. These include species of felids (puma, Geoffrey’s cat, and colo colo), three species of canids (all fox species of Pseudalopex), four camelids (guanaco, vicuna, and the domesticated llama and alpaca), and three cervids (huemul, northern huemul, and pudu). The mammal fauna of Chile are associated with five biogeographic areas: the summer rainfall Altiplano region of northeastern Chile, the Atacama Desert and adjacent winter rainfall Andes of northern Chile, the Andes of central Chile, the Mediterranean-climate region of central Chile, the Austral forests of southern Chile, and the Patagonian region.
In addition, 15 species of terrestrial mammals have become naturalized in Chile. Five of these occur only on the Juan Fernandez Islands, where they have greatly disrupted the structure and composition of the native flora.
The two native marsupials of Chile are part of the its legacy as a former remnant of Gondwana, ancestral home of all marsupials. Most notable is the diminutive monito del monte (Dromiciops gliroides) belongs to the most ancient lineage of marsupials alive today. In fact, this species constitutes its own an endemic family, the Microbiotheriidae. It is found in Chile’s winter-rainfall Valdivian forests.
The total bird diversity of Chile is only moderate. Including the oceanic islands of Pascua and Juan Fernandez and the Antarctic territory claimed by Chile, there are reports of 451 native species and five introduced species for Chile. The hotspot area includes 226 species, with 12 of these being endemic. The biogeographical isolation of the Chilean bird fauna shows parallels with that of the mammal fauna in the manner in which niches have been filled in unusual manners. Corvids, for example, are absent from Chile. Their role as scavengers has been filled by caracaras.
The 87 native species of terrestrial reptiles in Chile are divided into 7 families and 18 genera. These include six snakes (four genera) and 81 lizards (14 genera). Within the hotspot boundaries there are 41 reptile species, with 27 of these being endemic.
The diverse lizard fauna of Chile is strongly dominated by the family Tropiuridae, in particular the iguanid genus Liolaemus. This diverse genus and its evolution have been the focus of a large number of ecological and evolutionary studies. The occurrence of distinctive populations within individual species has led to the designation of a large number of subspecies. There are two endemic species of snakes. The highest diversity of reptiles in Chile occurs in the northern desert and Andean areas, outside of the core Mediterranean-climate region. These areas are also the site of the greatest degree of reptile endemism.
The amphibian fauna of Chile exhibits an unusually high level of endemism in comparison with other vertebrate groups. There are 43 native species in the hotspot of central Chile, 5 of the 12 genera being endemic. The centers of amphibian diversity in the region are the forests of south-central Chile. Only frogs and toads are native to the region; salamanders are conspicuous by their absence. More than three-quarters of these species are endemic to Chile, many of them rare and localized in distribution.
The native fish of Chile’s hotspot region number 43 species, including two endemic families.