Birds, about 8,600 species exist today; the natural turnover rate is about 1 per 230 years. Mammals, about 4,200 species exist today; the natural turnover rate is about 1 per 140 years.
As against these fairly low natural rates, during the last three decades alone some 95 species of birds and 37 of mammals have become extinct. Today some 200 species of birds and 100 of mammals are facing serious threats of extinction (Myers, 1979). One of the most interesting and curious of the carnivorous marsupials, viz., Thylacinus cynocephalus or the “Tasmanian Tiger” is now believed to be extinct. This animal combined a wolfish head with a tiger’s stripes, a snake’s gape, a kangaroo’s tail, plus a unique rear-opening pouch. The cause of its extinction was the merciless hunting by sheep farmers in Tasmania who were infuriated by the animals hunting their sheep. The most common cause of biotic extinction seems to be habitat alteration. Any natural habitat that is tampered with or used by man for his own purposes tends to become less suitable or unsuitable for the native wild species.
Westing (1981) est: mated that once every three years the global human population increases by some 215-225 million people at the expense of one species of wild bird or mammal plus at least one species of some group of plants or animals. Whales are the world’s largest animals, endowed with the largest sized brain in the animal kingdom. Conceivably, they may be even more intelligent than man. Sadly, however, the large-scale commercial whaling operations in many countries are posing a serious threat to the survival of the whale species.
An estimated 50,000 whales are hunted annually, with the sperm whale (Physester catodon) being the species of choice. This and several other species of whales are now on the international endangered species list. It is encouraging to note, however, that a meeting of the International Whaling Commission held in Brighton, England in July 1981, resolved to ban the hunting of P. catodon totally, and also to establish a whale sanctuary in the Indian Ocean where a moratorium will be placed on whaling for some period of time. A large number of species of cryptogamic and phanerogamic plants is also threatened with extinction all over the world. In Central Africa, some of the best wildlife preserves occur in northeastern Zambia. In the 1960s, overgrazing and over browsing by elephant and hippopotamus caused some destruction in the area.
Excessive increases in the populations of these and other large mammals are, therefore, harmful for preserving the other species of wild plants and animals. However, even more serious than grazing and browsing is the factor of fire which exerts a strong negative influence on wildlife. In Eastern Africa, elephants and fire have been responsible for causing the rapid replacement of woodland and forest life by grasslands. When the numbers of large mammals as well as outbreaks of fire are controlled, then the forest along with its associated wild biota is effectively conserved. Of course, the essential first and major step in the management of ungulates and other wildlife is to conserve their natural habitat, or to create more such habitats and to improve the existing ones so as to make them more suitable for the wildlife.
For instance, low trees and shrubs, with or without a tall tree overstorey, are important as both food and cover in the habitats of some species of wild deer (Odocoileus virginianus). Fire and certain other factors which set back forest communities to a shrub stage tend to favour these deer, and hence controlled fires can be used to manage such species in nature. Fire stimulates the production of more abundant, available, and nutritious fodder for the deer. The prestigious Indian Project Tiger was launched in 1973 with a view to ensuring the survival and maintenance of the then rapidly dwindling population of tigers (Panthera tigris) and to preserve their habitats.
The project covers over 15,000 square km of area which is about 2 per cent of the total forest area and about 0.48 per cent of the total geographical area of India. Within a few years after the start of the project, the decline in tiger population was successfully arrested and now the population has started to rise. The Asian Lion (Panthera leo persica) is also facing some threats to its survival. These include increasing deforestation and the heavy pressure of grazing by professional shepherds in its area. Current estimates suggest that the total population count of the Asian Rhinoceros is about 1,600.
The main threat faced by rhinoceros is the commercial value of its horns for which poachers kill rhinoceros. India is estimated to have about 350 species of mammals and about 1,200 species of birds. The population figures for some of the endangered species are: lions 205; tiger 3,015; rhinoceros about 1,600; elephants 15,000; brown antelered deer-30; Kashmir stag (hangul) 385; and black-necked crane 11.
With increasing deforestation, urbanization, and population growth, many habitats of wild plants and animals have been changed or destroyed. Even during the times of the Mughal rulers, India was very rich in virgin forests, climax vegetations, and clean natural habitats conducive to wildlife. Compared to those times, the tiger, leopard, bear and some other populations have greatly declined now and wild pig, monkeys and rodents are also much more restricted now than 400 years ago. The same is true for vegetation: away from the Terai and narrow riverine strips, we now find very little real woodland, even though some relics and cultivated patches of Butea, Melia, Acacia, and Zizyphus occur here and there. Apart from the widespread and extensive destructions of habitats, direct extermination of many species of wildlife has occurred through the actions of hunters and poachers. During the past two centuries, at least two species of birds and 15 of mammals are recorded to have been exterminated in India (Mani, 1974). For instance, the pink headed duck (Rhodonessa caryophyllacea) which was commonly seen in Assam in the early 1900s, can no longer be found now. The distributions of Cairnia scutulata, Ophrysia superciliosa, Choriotis nigriceps and several other birds have been greatly restricted during the past few decades.
A langur (Presbytis johni) which was widely distributed throughout South India a few decades ago is now confined to the southern part of Western Ghats only. According to Mukheijee (1974), there has been a pronounced impoverishment in the terrestrial vertebrates of India during the last few decades. The distributional ranges of many species have shrunk markedly. Some examples from various groups include reptiles (Crocodilus palustris), birds (Cursorius bitorquatus), mammals [(Equus hemionus khur (wild ass), Rhinoceros unicornis, R. sumatrensis, Bosgrunniens mutus, Capra falconeri (wild goat), Moschus moschiferus (musk deer), Panthera leo persica (Asiatic lion), and Antelope cervicapra (black buck)]. Mukherjee feels that the above faunal impoverishments have occurred not as a result of climatic or physiographic influences but as a result of human activities.
Man has destroyed or greatly changed their habitats, occupying them himself. In olden times, people used to protect or even worship several animals and plants which were considered sacred and areas around temples were sanctuaries for wild animals and plants, some of which were even fed by the devotees! These ancient customs, beliefs and religious taboos are now being gradually or abruptly abandoned by the younger people and this is one factor that has harmed wildlife, at least around places of worship, if not elsewhere. In recent years there has been a growing awareness in many countries to conserve wildlife.
To achieve this objective, many countries have banned trade in endangered species (or their products) such as the African Elephant (till hitherto widely hunted for ivory), the chimpanzee, the cheetahs, various species of parrots, and certain fur-yielding animals. In India, attempts are being made to save the bustard (Chlamydotis undulata), snakes, lizards, pheasants, and other animals from serious declines in their population sizes.