Wildlife extinction results from many forces operating in the society, such as economics, politics and psychology, the specific activities that cause extinction of species and the relative importance of each.
Some factors affect wildlife directly and others affect it indirectly. Let us examine each of these factors in a little more detail.
a) Alteration of habitat:
Destruction of the habitat of a particular wildlife species intentionally or unintentionally leads to extinction of species. The habitat may be destroyed by deforestation, drainage, overgrazing, expanding agriculture, urban and suburban development, highway construction, dam building, etc. As a result of destruction of its habitat, the species must either adapt to the changes, move elsewhere or many succumb to predation, starvation or disease and die.
b) Commercial sport and subsistence, hunting:
Nature has great diversity. It is created, over many millions of years, a large number of species of plants and animals. But it is man who is responsible for the extinction of plant and animal species either directly or indirectly.
It may be a coincidence that all the motives for killing materials begin with the letter ‘F’: food, fats, finery (fur and feathers), fun, financial gain and fear. From time immemorial, man has hunted for food. It is only in relatively recent times that man is killing animals on a large scale for economic gains or even for sport.
Commercially, animals are hunted for their fur, hides, tusks, antlers and various other body parts. Rhinoceros is hunted for its horns. Gharial and crocodile are hunted for their skin, which is used for various purposes. One of the most publicized commercial hunts is that of a whale. The “whalebone” or “baleen” was used to make combs and other products.
Hunting for sport is also a factor in wildlife extinction. Poaching of wildlife for sport and profit is widespread.
c) Introduction of foreign species:
The introduction of foreign or alien species into new territories can often lead to ecological and economic disaster. An introduced species’ niche may overlap that of a native species, the newcomer may out-complete the native species, resulting in its extinction. Through, species are often intentionally introduced to improve fishing and hunting, it can lead to problems also.
d) Control of pests and predators:
Natural predators remove the aged, sick and injured members of the prey population. In contrast, human beings generally remove the strongest specimens. Such predation will diminish the genetic vigor of a population.
Thus, human being and natural predators have opposing effects on population of prey. Natural predators make the prey population stronger, human beings make it weaker. Predators or pests are also important biotic components of the ecosystem and so great care should be taken while dealing with these components.
Human beings hunt, trap and poison predators and pests such as bears, wolves, lion, etc. in general, predator and pest control measures have two major impacts: (i) they will natural predators that are a part of the balanced ecosystem, (ii) they can indiscriminately poison non-target species, having a ripple effect on organisms higher in the food chain.
e) Collection for zoos, private collections and research:
Animals and plants are gathered throughout the world for zoos, private collectors and researchers in biology and medicine. Among the legally exported animals, there are many endangered, threatened and rare species. Researchers throughout the world use a variety of animas for their studies, many or which come from the wild.
Particularly primates such as monkeys and chimpanzees are sacrificed for research. Primates are desired because of their anatomical, genetic and physiological similarly to human beings. The chimpanzees, for example, are being used in work on human reproduction and cancer detection. Research animals often do not breed in capacity. They also have a high mortality, resulting in continual loss of wildlife.
Moreover, the regulations for the supply of animals are poorly enforced. The hunters also know very little about effective live capture; therefore, deaths and injuries during capture are not uncommon. It is not only animals but plants like cacti and orchids are also being uprooted for sale elsewhere.
Pollution alters the habitat of plants and animals and plays a significant role in extinction. Water pollution is especially harmful to the organisms living in estuaries and coastal zones. Toxic wastes entering the food chain can have devastating effect on their pollution. Insecticides and pesticides can also affect the plants and animals.
Other Ecological factors:
There are other ecological factors that contribute to species extinction. Some of these are as follows:
i) Degree of specialization is an important factor. The more specialized an animal or plant is, the more vulnerable it is to extinction.
ii) Location of the organism in the food chain is also important. The higher the animals are in food chain, the more susceptible it becomes. Larger animal are more profitable to hunt and they are easy target s because they are less fearful of human beings.
iii) The distribution range also affects extinction. The smaller the range, the greater the threat of extinction. Population on island are particularly susceptible.
iv) Reproductive range also an important factor. Large organisms tend to produce fewer offspring at widely spaced intervals. Their offspring also tend to reach reproductive age late.
v) Animal’s tolerance of human presence of specific behavioral patterns also play an important role.