Associated with the variety of Indian habitats is a fauna that includes a rich assemblage of birds, mammals, amphibians, reptiles and invertebrates. As with the Indian flora, the animal life is derived from those of neighbouring regions-primarily from the east, but also from Africa and Eurasia. The richest animal communities appear to inhabit the humid forests of the north-eastern hills and the uplands of the south-western Peninsula. These two 'pockets' of high endemism are all the more remarkable because they show such close similarities, in spite of being separated by some 2500 kilometres. The closest relatives of many animal species of the Western Ghats are to be found in Assam or Burma. As with the plant life, the animal forms in India appear to have originated in other areas. The forests of Burma and Indo-China appear to be a centre of origin for the bulk of land vertebrates found in India today.
In India birds are a spectacular, rich and easily observable segment of the fauna. Every Indian habitat is enlivened by conspicuous and colourful forms. Some 1200 species in 75 families have been recorded for India. Prominent components of this avifauna include 46 species of pheasant and quail. The peafowl, one of the grandest of the pheasants, and the National Bird, occurs throughout most of India in wooded habitats. The region's richest assemblage of pleasant species, however, inhabits the Himalayan uplands.
Woodpeckers (33 species in India) are nearly cosmopolitan in distribution. Many Indian habitats support five or more species in this group of hole-nesters. The babblers (123 species in India) and the bulbuls (18 species) are primarily Indo-Malayan, but also reach Africa. These and a number of other insect-eating groups, especially the minivets, wood-shrikes, drongos, flycatchers and nuthatches, often gather into regular multi-species foraging groups. They move through the forest in noisy parties, stirring up insect prey and helping each other keep watch for attacks from hawks or other predators.
Many Indian bird families, especially those of the Himalayan region, are of Eurasian origin, in particular the finches, accentors and warblers. These more northerly forms are primarily insectivorous and granivorous. Many are migratory, nesting in the northern latitudes when spring conditions are ideal, then in autumn traversing the Himalayan chain and taking refuge on the Indian Peninsula, to avoid the cold northern winters.
Among India's birds of tropical affinity, one finds more species that specialise in eating fruit. The parrots and pigeons are two groups that have prospered in tropical environments. Less known but also important as frugivores are the barbets stocky and often colourful relatives of the woodpecker family. The hornbills are prominent fruit-eaters. These large-billed, gregarious birds are important dispersers of seeds in the forest. Many tree species are probably dependent upon the hornbills and barbets for effective distribution of their seeds. The tree provided temptingly edible fruit to entice the hungry bird. Having consumed the fruit, the bird unwittingly carries the seed elsewhere and drops it. Thus good nutrition is traded for effective transportation of seeds from the parent plant.
The Indian mammal community is quite diverse, especially in relatively large forms. Elephant, rhinoceros and the Indian bison (gaur) are among the largest land mammals. Until recently, India was home to three species of rhinoceros, more than any other region. Fourteen species of cats, including four large forms (tiger, leopard, snow leopard and clouded leopard) inhabit jungle, plain, hill and high Himalaya. The Gangetic dolphin is one of India's oddities-a large fresh-water cetacean that inhabits the Ganges, Indus, and Brahmaputra and their larger tributaries.
Deer (nine species), sheep (nine species), antelope (five species) and their relatives abound in the Indian region. Member species range in size from the tiny chevotrain (12 inches at the shoulder) to the grand sambar. An adult male of the latter can grow to 700 pounds. Primates are conspicuous inhabitants of most India environments. In the north-east one can find seven species. The Western Ghats support three endemic forms; slender loris, lion-tailed macaque and Nilgiri langur. The nearest allies to the latter two forms live in the forests of the north-eastern hills. Surprisingly, the closest ally to the slender loris is the angwantibo of West Africa.
India, of course, is famous for its snake fauna in the form of its deadly cobras and monstrous pythons. Some 388 species of snakes are recorded from the region. Exceptional specimens of the reticulate python have measured up to 9.7 m, and share with the neo-tropical anaconda the epithet of the world's longest snake. The king cobra is the largest known venomous snake.
India is rich in butterflies. The present-day butterfly fauna appears to be largely of recent origin, a product of the vast influx of eastern forms subsequent to the contact of 'proto-India' with the Asian continent. At least some genera are of East African origin. It is interesting to speculate whether these forms arrived in India via overland dispersal (through Ethiopia and Arabia), or whether they are relics of Peninsular India's ancient Gondwanaland association.