Tigers are disappearing in the wild at an unprecedented rate. The primary threats to tigers are from human activities, including habitat destruction that results in population fragmentation and tiger poaching. Beginning early in the 20th century, Asia experienced enormous population growth. As populations expanded, farms, villages, and cities transformed once vast wilderness areas. People and their activities now dominate the landscape. Further, the forests that remain are degraded—people have scoured the area removing fodder (food for domestic livestock) and other products, including the tiger’s essential prey, the deer and pigs that people prize as food as much as tigers do. Some of the places tigers could live—where enough forest still exists—are ghost towns because there is nothing left for the tigers to eat.
If all the remaining 5,000 to 7,000 wild tigers lived in one continuous interbreeding population they would not be as endangered as they are. But rapid habitat loss has caused tiger populations to become fragmented into more than 160 isolated sub-populations that are scattered over Asia. On average, each of these sub-populations consists of only about 40 individuals. Such small populations, living in small areas that average less than 500 sq km (200 sq mi) in size, can suffer from chance variations in birth and death rates. For example, all cubs could be male or female, which affects healthy reproduction and over time can lead to extinction. Another problem caused by this fragmentation is inbreeding, in which close relatives mate. Inbreeding can result in genetic disorders that can lead to increased cub mortality and weakened resistance to diseases. Small populations are also vulnerable to infectious diseases and natural disasters, such as drought or fire. Any one of these events could wipe out an entire subpopulation. In animal populations with fewer than 50 reproducing females, like most of the existing tiger sub-populations, these risks become especially dangerous.
Throughout most of the 20th century tigers were killed for sport hunting and to sell their body parts, including fur for the fashion industry. Today hunting tigers is illegal in most countries where the animals are found, but poachers are still killing tigers in large numbers. The poachers sell tiger body parts on the black market, particularly bones used in medicines for traditional Chinese medicine (TCM), a formalized system of health care utilizing such therapeutic treatments as herbal medicine, acupuncture, and nutrition, which is practiced by 25 percent of the world’s population.
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