Wednesday, October 24, 2007

VII. Habitat:

Tigers are found in a variety of habitats, including both tropical and evergreen forests, woodlands, grasslands, rocky country, swamps, and savannas. The Caspian tiger was also found in steppes and mountainous areas. Compared to the lion, the tiger prefers more dense vegetation, for which its camouflage is ideally suited, and where a single predator is not at a disadvantage compared to a pride. Among the big cats, only the tiger and jaguar are strong swimmers; tigers are often found bathing in ponds, lakes, and rivers. Tigers rely on concealment for stalking and ambushing prey. They seek areas with ample food, water, and moderately dense cover. Tigers travel throughout the year in individual home ranges. Tiger home range sizes differ depending on habitat quality, prey availability, the tiger's sex, and the season. a. In India, where prey densities are relatively high, home ranges vary from 50 to 1,000 square km (19-386 square mi.). In Manchuria and southeastern Siberia, where prey are more widely dispersed, home ranges vary from 500 to 4,000 square km (193-1,544 square mi.).
Because tigers are polygynous (males have more than one female mate at one time), male tigers generally have larger home ranges than females. A study in Nepal showed that males have home ranges of 19 to 151 square km (7-58 square mi.), while females have home ranges of 10 to 51 square km (4-20 square mi.). Home range sizes may also vary seasonally. Female tigers in Nepal studies, have larger ranges in the hot season and smaller ranges in the wet season. Females also had smaller home ranges when caring for young cubs. Since tigers do not migrate, where prey is migratory or widely dispersed, like in the Russian Far East, females tend to have overlapping ranges. Some tigers establish exclusive home ranges, or territories. The home ranges of male tigers are intrasexual territories. Male tigers exclude other males from their range, but not females. A male's home range usually overlaps the home range(s) of one to several females. Female tigers may or may not establish territories. Females living in areas with a seasonally stable prey population, like the Royal Chitwan National Park in Nepal, usually establish territories. In Kanha Park, India, female tigers studied in the 1960s had overlapping home ranges. By the 1970s, habitat quality and prey availability had improved, and females were reported establishing non-overlapping home ranges.
Female and male tigers mark their home ranges chemically (through scent) and visually. Most marking is done along home range boundaries. The most common form of scent marking is through urine. A chemically modified urine called marking fluid, which has a strong, long-lasting smell, is sprayed on trees, bushes, and rocks. Scraping (abrading the ground with the hind feet) is a common visual marker, placed in conspicuous areas along pathways. Scraping is often accompanied by deposits of feces or urine. Less common methods of marking include tree trunk clawing, cheek rubbing, and flattening of vegetation (through rolling) next to trails. Daily movement within the home range varies. Individuals will visit all parts of their range over a period of days or weeks. Siberian tigers have been recorded moving up to 60 km (37 mi.) per day, while Bengal tigers in Nepal covered about 10 to 20 km (6-12 mi.) per day. Adult female tigers (tigresses) tend to occupy the same home range for their entire lifetime, while males may shift or change their home range several times. Vacant home ranges in prime habitat are quickly filled by animals living in peripheral habitats, usually young adults.



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