The mammals are the class of vertebrate animals characterized by the presence of mammary glands, the presence of hair or fur; specialized teeth; the presence of a neocortex region in the brain; and endothermic or 'warm-blooded' bodies. The brain regulates endothermic and circulatory system, including a four-chambered heart. In India there are 410 species, 186 genera, 45 families and 13 orders of which nearly 89 species are listed as threatened in the International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Animals (IUCN 2006).

The four-horned antelope (Tetracerus quadricornis), or chousingha, is a species of small antelope found in open forest in India and Nepal. Standing only 55 to 64 cm (22 to 25 in) at the shoulder, it is the smallest of Asian bovids. Males of the species are unique among extant mammals in that they possess four permanent horns. Four-horned antelope live in a variety of habitats across their range, but prefer open, dry, deciduous forests in hilly terrain.They generally stay away from human-inhabited areas.

IUCN Status: Vulnerable (VU) Photo: Sahana Chattopadhyay