Tigers have binocular vision, because the field of vision of each eye overlaps to make a three-dimensional image. A tiger's night vision is six times better than a human's, according to the San Diego Zoo. A tiger's eyes reflect light back, which helps it make a better picture in dim light. Tigers find their prey by using sight and sound, and Amur tigers have large ears that are cup-shaped, which lets them catch and focus sounds.
Tigers hunt mostly at night, and they may cover as much as 16 to 32 kilometers in a single night. A tiger can stalk its prey for 20 or 30 minutes, moving slowly and quietly. Tigers can leap 8 to 10 meters, though leaps of half that distance are more typical.
Tigers are seldom far from a water source. By day they are often found relaxing or waiting to ambush prey in ponds, streams and rivers. Tigers often go into the water to escape flies or to cool off. Tigers can easily cross rivers up to 8 kilometers wide, and tigers have been known to cross a width of 29 kilometers in the water. Tigers also have partially webbed toes.
Tigers can live in warm, wet forests and in places with heavy snow where temperatures may fall as low as -40 degrees Celsius. Tigers have been found as high as 3,960 meters above sea level. In general they need only some plant cover, a source of water and enough prey. Amur tigers live in snowy forests in eastern Russia and northeastern China, and they have thick fur on their paws that keeps their feet warm, lets them walk silently and works like snowshoes in snow.
Earlier, India estimated its tigers with track counts that identified individual tigers by their pug marks (footprints). This failed to give reliable estimates because of erroneous assumptions. Most early methods of counting tigers failed because they did not take three things about tigers into account: tigers are scarce, their range is huge, and they are secretive. In the 1920s a British forester in India, F.W. Champion, used cameras with tripwires to photograph tigers and leopards in the foothills of the Western Himalayas. In four Indian reserves, researchers estimated 28 tigers in Kanha, 27 in Nagarhole, 22 in Kaziranga and only 5 in Pench.
The San Diego Zoo and the Smithsonian's National Zoo count six living subspecies of tigers. The Amur tiger is the largest kind of tiger, and the Sumatran tiger is the smallest kind. Sumatran tigers weigh up to 140 kilograms.
A tiger mother is pregnant for about three months, and she usually has 2 or 3 cubs at a time. Tiger cubs are born small and helpless, and a tiger cub's eyes do not open until 6 to 14 days after birth. A mother tiger begins teaching her cubs to hunt at about 3 months. The cubs stay with their mother for about two years. Wild tigers usually live 10 to 15 years, and tigers mostly live alone.
Words to know
- binocular: two-eyed
- overlaps: lies over
- webbed: joined by skin
- reserves: protected lands
