Historical Changes In Indian Fauna
The preceding section highlighted the diversity of Indian animal forms. After such a discussion, it is surprising to note that from all indications, India's wildlife is poorer and much less widespread than it was in earlier times. It seems that many of the animal distributions in modern India are relictual-fragments of larger former ranges.
The rhinos offer an extreme example. While Prater lists three species from India, only one of these is still known to exist in the region, two having been extirpated within the last century. The geographic range of surviving species has been reduced by ninety-nine per cent during the last century. Note that at least two additional rhino species are known from India from fossil remains. In this example we see reduction in species-richness (formerly five, now only one species extant) and distributional reduction to relictual geographic ranges.
Thus we can measure faunal impoverishment in two ways: (1) reduction in numbers of species (extinction) and (2) restriction or insularisation of geographic ranges. Extinction is in evidence when examining the fossil record. Numbers of forms still extant in other continental regions are known in India only as fossil remains; baboon, orang-utan, chimpanzee, camel, giraffe and hippopotamus. Mukherjee highlights the full extent of reduction in range. The distribution of several species of duck, members of the bustard family, the black buck and lion, show severe reduction in range. Many other examples support this trend.
A further example of biogeographic regression is provided by the many faunal 'specialities' of the Western and Eastern Ghats. Of the unusual forms found in these peninsular uplands most or perhaps all show a close affinity to forms inhabiting the north-eastern hill region. The small populations in the ghats are relict populations of forms that must have once been distributed across the Peninsula. The humid upland forests of the ghats act as faunal refuges for these forms that have been wiped out except in the richest and least disturbed habitats.