Friday, February 4, 2011

LION


The lion (Panthera leo) is one of the four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg (550 ) in weight, it is the second-largest living cat after the tiger. Wild lions currently exist in Sub-Saharan Africa and in Asia with an endangeredremnant population in Gir Forest National Park in India, having disappeared from North Africa and Southwest Asia in historic times. Until the late Pleistocene, about 10,000 years ago, the lion was the most widespread large land mammal after humans. They were found in most of Africa, across Eurasia from western Europe to India, and in the Americas from the Yukon to Peru. The lion is a vulnerable species, having seen a possibly irreversible population decline of thirty to fifty percent over the past two decades in its African range. Lion populations are untenable outside designated reserves and national parks. Although the cause of the decline is not fully understood, habitat loss and conflicts with humans are currently the greatest causes of concern.
Lions live for ten to fourteen years in the wild, while in captivity they can live longer than twenty years. In the wild, males seldom live longer than ten years, as injuries sustained from continual fighting with rival males greatly reduce their longevity. They typically inhabit savanna and grassland, although they may take to bush and forest. Lions are unusually social compared to other cats. A pride of lions consists of related females and offspring and a small number of adult males. Groups of female lions typically hunt together, preying mostly on large ungulates. Lions are apex and keystonepredators, although they scavenge as opportunity allows. While lions do not typically hunt humans, some have been known to do so.
Highly distinctive, the male lion is easily recognized by its mane, and its face is one of the most widely recognized animal symbols in human culture. Depictions have existed from the Upper Paleolithic period, with carvings and paintings from the Lascaux and Chauvet Caves, through virtually all ancient and medieval cultures where they once occurred. It has been extensively depicted in sculptures, in paintings, on national flags, and in contemporary filmsand literature. Lions have been kept in menageries since Roman times and have been a key species sought for exhibition in zoos the world over since the late eighteenth century. Zoos are cooperating worldwide in breeding programs for the endangered Asiatic subspecies.
Group organization
Lions are predatory carnivores who manifest two types of social organization. Some are residents, living in groups, called prides. The pride usually consists of five or six related females, their cubs of both sexes, and one or two males (known as a coalition if more than one) who mate with the adult females (although extremely large prides, consisting of up to 30 individuals, have been observed). The number of adult males in a coalition is usually two, but may increase to four and decrease again over time. Male cubs are excluded from their maternal pride when they reach maturity. The second organizational behaviour is labeled nomads, who range widely and move about sporadically, either singularly or in pairs.] Pairs are more frequent among related males who have been excluded from their birth pride. Note that a lion may switch lifestyles; nomads may become residents and vice versa. Males have to go through this lifestyle and some never are able to join another pride. A female who becomes a nomad has much greater difficulty joining a new pride, as the females in a pride are related, and they reject most attempts by an unrelated female to join their family group.
The area a pride occupies is called a pride area, whereas that by a nomad is a range. The males associated with a pride tend to stay on the fringes, patrolling their territory. Why sociality—the most pronounced in any cat species—has developed in lionesses is the subject of much debate. Increased hunting success appears an obvious reason, but this is less than sure upon examination: coordinated hunting does allow for more successful predation, but also ensures that non-hunting members reduce per capita caloric intake, however, some take a role raising cubs, who may be left alone for extended periods of time. Members of the pride regularly tend to play the same role in hunts. The health of the hunters is the primary need for the survival of the pride and they are the first to consume the prey at the site it is taken. Other benefits include possible kin selection (better to share food with a related lion than with a stranger), protection of the young, maintenance of territory, and individual insurance against injury and hunger. Lionesses do the majority of the hunting for their pride, being smaller, swifter and more agile than the males, and unencumbered by the heavy and conspicuous mane, which causes overheating during exertion. They act as a co-ordinated group in order to stalk and bring down the prey successfully. However, if nearby the hunt, males have a tendency to dominate the kill once the lionesses have succeeded. They are more likely to share with the cubs than with the lionesses, but rarely share food they have killed by themselves. Smaller prey is eaten at the location of the hunt, thereby being shared among the hunters; when the kill is larger it often is dragged to the pride area. There is more sharing of larger kills,  although pride members often behave aggressively toward each other as each tries to consume as much food as possible.
Both males and females defend the pride against intruders. Some individual lions consistently lead the defense against intruders, while others lag behind. Lions tend to assume specific roles in the pride. Those lagging behind may provide other valuable services to the group. An alternative hypothesis is that there is some reward associated with being a leader who fends off intruders and the rank of lionesses in the pride is reflected in these responses. The male or males associated with the pride must defend their relationship to the pride from outside males who attempt to take over their relationship with the pride. Females form the stable social unit in a pride and do not tolerate outside females; membership only changes with the births and deaths of lionesses,although some females do leave and become nomadic. Subadult males on the other hand, must leave the pride when they reach maturity at around 2–3 years of age.

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