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TIGERS

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TIGERS

Post by ambuj@chauhan on Mon Apr 27, 2009 2:30 pm

Tiger
I INTRODUCTION

Tiger, largest member of the cat family and the only cat with striped fur. Perfectly designed predators, tigers possess beauty, grace, and awesome power. Their presence in the wild, revealed by a throaty roar or a track on a dusty trail, electrifies the forest and sends shivers down the spines of all who share its space. Humans admire tigers as much as they fear them and the animals figure prominently in Asian myths, religions, arts, and imagination. Tigers were once found throughout the forested regions of tropical and temperate Asia. Excessive hunting and destruction of tiger habitat have now narrowed the tiger’s range to a few isolated patches throughout Asia. Many people have organized local and international conservation organizations to prevent tigers from becoming extinct.

Among the 36 cat species, tigers are most closely related to lions, leopards, and jaguars. These cats evolved from a common ancestor that was probably similar to modern leopards or jaguars and lived more than 5 million years ago. The earliest fossils clearly identified as those of tigers are about 2 million years old. These fossils were found in central Asia, eastern and northern China, Siberia, Japan, Sumatra, and Java. Based on fossils dating from 300,000 to 10,000 years ago, some scientists think that tigers may have ranged into present-day Alaska via the Bering land bridge that once joined Alaska and Siberia during the last glaciation in the Pleistocene Epoch. Other scientists believe that the big cat fossils found in Alaska all belong to lions.

Scientists use a variety of methods to study the behavior of tigers and track their movements. Radio tracking was first used to track tigers in Nepal in 1973. In this method, a collar with an attached radio transmitter is placed around the neck of a tiger. Scientists monitor the radio transmissions as the tiger travels, tracking the tiger’s whereabouts to learn about its range, life history, and behaviors. More recently, scientists have set up camera traps that are triggered by an infrared beam. When a tiger crosses the infrared beam, the camera snaps a shot of the tiger, recording the date and time the photograph was taken. The tiger’s unique stripes help identify the animal, and when the same animal triggers other camera traps, the photo archives enable scientists to gather information about the tiger’s movements. This method helps scientists estimate tiger numbers in the wild.

II RANGE AND HABITAT

Scientists estimate that at the beginning of the 20th century 100,000 tigers flourished throughout Asia, from eastern Russia and Korea through eastern and southern China, Southeast Asia, the Indian subcontinent, and into Pakistan, with separate populations around the Caspian Sea and on the Indonesian islands of Bali, Java, and Sumatra. At the start of the 21st century only 5,000 to 7,000 tigers lived in the wild in just 14 Asian countries: Bangladesh, Bhutan, Cambodia, China, India, Laos, Malaysia, Myanmar (formerly Burma), Nepal, North Korea, Russia, Sumatra, Thailand, and Vietnam. Tigers are now extinct in Bali, Java, and around the Caspian Sea, and nearly so in China and North Korea. Less than 20 percent of today’s tiger habitat is located in national parks or other protected areas, which means that the majority of the areas where tigers live could be lost to other uses, such as agriculture or urbanization.

Tigers are territorial—they live alone in large areas that they defend from other tigers. The ideal tiger territory is a large forested area with rich vegetation for cover, plentiful water to drink and cool off in, and abundant deer, swine, and other large mammals to eat. With these three essentials, tigers can thrive in diverse habitats and climates including hot, tropical rain forests in Sumatra and Southeast Asia; cool oak and pine forest in the Amur River Valley in far eastern Russia; tall grass jungles in India and Nepal; coastal mangrove forests in Bangladesh; and mountain slopes in Bhutan.



VII TIGER STATUS

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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