Cheetah - biology.

Cheetah - biology. I INTRODUCTION Cheetah, member of the cat family, and one of the fastest land animals in the world. A cheetah can accelerate to a running speed of more than 97 km/h (60 mph) in just two to three seconds, sustaining that speed for up to 300 m (1,000 ft). Until about 100 years ago cheetahs were found in open habitats throughout Africa, the Middle East, and southwest Asia as far as central India. Excessive hunting and habitat destruction have reduced the cheetah's range to isolated parts of Africa south of the Sahara, where around 10,000 cheetahs now live. Fewer than 100 cheetahs remain in remote areas of Iran. Scientists classify the cheetah in its own genus because of its physical distinctiveness from other cats, although genetic studies suggest that the cheetah may share a common ancestor with the North American puma. Fossil evidence shows that cheetahs may have originated in North America as early as 3 million years ago and then spread into Eurasia and Africa. Scientists theorize that around 12,000 years ago a significant climate change caused a rapid decline in the cheetah population, with only a small group of cheetahs surviving in Eurasia. Inbreeding (mating between close relatives) likely occurred as this tiny population slowly grew over generations. As a result of this inbreeding, today's cheetahs lack genetic variation, which may make them less able to adapt to changes in the environment, such as infectious disease or a climate change. Overhunting and habitat destruction place cheetahs at high risk for extinction. Farmers often kill cheetahs to prevent them from threatening their livestock. Scientists have developed breeding programs intended to provide insurance against their extinction in the wild, and they are working with local communities in Africa to reduce conflicts between people and cheetahs. Scientists primarily study cheetahs in the wild by using radio tracking, in which a collar with a radio transmitter attached is placed around the neck of a cheetah. Scientists monitor the radio transmissions as the cheetah travels in order to track the cat's whereabouts and learn about its life history and behaviors. Some scientists also keep a photographic archive of individuals within a population. They are able to distinguish one cheetah from another by a distinctive pattern of rings on the tail. This photographic record helps scientists monitor individual cheetahs over the course of their lives. II HABITAT AND RANGE Cheetahs are well adapted to dry habitats such as savanna grasslands and semideserts. They can survive for long periods without water, gathering much of the water they need from the body fluids of their prey. Cheetahs prefer open habitats that offer unobstructed views of their surroundings; such habitats make it easier to detect prey as well as predators. When stalking prey, however, cheetahs use the camouflage protection of bush, scrub, and other vegetation. Although their populations were greatly reduced during the 20th century, as the 21st century began cheetahs still inhabited a broad section of Africa, including areas of the Sahel, East Africa, and southern Africa. Namibia has the largest population of cheetahs, with about 2,500 individuals. Smaller populations exist in Botswana, Zimbabwe, South Africa, Kenya, and Tanzania. III PHYSICAL DESCRIPTION The name cheetah comes from the Hindu word chita, meaning "spotted one," a reference to the cheetah's light brown to tawny yellow coat that is covered with round, solid-black spots of various sizes. The spots merge into a band pattern on the end of the tail that is distinctive in each individual cat. A long vertical stripe extends from the lower inside corner of the eye to the edge of the mouth. Adult cheetahs measure 112 to 140 cm (44 to 55 in) from head to rear end and stand 66 to 94 cm (26 to 37 in) at the shoulder. A long tail extends 61 to 79 cm (24 to 31 in) in length. Cheetahs usually weigh around 39 to 65 kg (86 to 143 lb). Male cheetahs are generally bigger than females, but the size differences between the sexes are not as large as in other big cats, such as lions, tigers, and jaguars. All cats are speedy runners, but the physical features adapted for speed are developed to the extreme in cheetahs. The cheetah body is well muscled, lithe, and streamlined. The cheetah has long, slender legs and an elongated spine with large muscles for flexing and stretching, enabling the animal to increase its stride length during high-speed chases. The long tail acts as a rudder to maintain balance at high speeds. Enlarged nasal and sinus passages and lungs, as well as an oversized heart, support the extensive oxygen exchange needed during fast runs. For good traction, the small, tough pads on cheetah paws are ridged. The claws are blunt and only slightly curved. The claws partially retract into sheaths, springing out from the sheaths when the cat strikes an animal. A sprinting cheetah runs in what is called a rotary gallop. Its hind limbs land first, on alternate sides, providing the explosive force needed to flex the spine and float the body with all limbs outstretched off the ground, as if in suspended flight. Next, the forelimbs land, one at a time, followed by a stage when all four feet are gathered directly under the body. Lacking a sweating mechanism, cheetahs internally store the heat produced by a high-speed sprint. As a result, cheetahs must catch their prey or abandon the chase after about 300 m (about 1,000 ft)--any longer and the cheetah's internal body temperature would rise to lethal levels. The cheetah has a small skull with a short muzzle, and its jaw is weaker than the jaws of other big cats. Cheetahs have 30 teeth, 15 on each side of the mouth. Their teeth are relatively smaller than those of other cats, leaving more room for the expanded nasal passages that help cheetahs run at such swift speeds. Scissor-like molars slice flesh, and small incisors scrape meat from bones. Like all cats, cheetahs have excellent vision. The cheetah's eyes have an elongated fovea (an area in the retina) that gives the cheetah a sharp, wide-angle view of its surroundings. The cheetah uses its vision and its acute sense of hearing and smell to locate and track prey. IV BEHAVIOR Cheetahs may live singly or in small groups. Adult females live alone, except when raising cubs. After the cubs leave their mother, the siblings stay together for about six months before females separate from the group to go off alone. Brothers often stay together in groups of two to four, known as coalitions, for the rest of their lives. These coalitions may also include unrelated males. About half of all males live alone. When communicating with one another, cheetahs do not roar; instead they make a variety of vocalizations, including purrs, bleats, barks, and chirps, that sound remarkably like those of a bird. Cheetahs range over large areas in search of food. In Tanzania, where cheetahs have been best studied, a female's home range may be as large as 800 sq km (300 sq mi) as she follows prey, such as Thomson's gazelles, that migrate seasonally over long distances in search of fresh grass. A female's home range tends to overlap with the home ranges of other females since no one female could defend such a large area, but females tend to avoid each other. Most males also range over huge areas, but about a third of males defend smaller territories that are about 40 sq km (15 sq mi) in size. In addition to abundant prey, important features of a territory include rocky outcrops or clumps of trees and bushes--sites that females choose for giving birth and raising cubs and where males are most likely to breed. Male coalitions often fight fiercely to obtain a territory, which they defend from intrusion by single males. Cheetahs prey on various species of gazelles, impalas, hares, and young wildebeests. Males in coalitions sometimes hunt cooperatively, enabling them to kill larger animals such as zebras. Unlike most cats, cheetahs hunt during the day, when lions and hyenas that compete with them for prey are less likely to be active. Still, scientists in Tanzania have observed that cheetahs lose 10 to 13 percent of their kills to lions and hyenas. Alerted by the panic of a gazelle herd or by the circling of vultures, lions and hyenas close in and easily drive the more timid cheetah away from a fresh kill. A cheetah usually stalks prey to within about 10 m (about 33 ft) and then bursts into a sprint to close the gap. About half of these chases result in a kill. Other big cats typically rely on a piercing bite to the neck to kill prey. A cheetah's weak jaw and smaller teeth require that it grasp the throat of its prey until the animal suffocates, a tactic other big cats use only when killing prey that is larger than they are. V REPRODUCTION Male and female cheetahs come together for brief mating periods that last one to three days. Copulation is infrequent and typically occurs at night. Following a 90- to 95-day gestation (the period from conception to birth), about four or five cubs, and sometimes as many as eight cubs, are born in a litter. Cubs are blind and helpless at birth, weighing around 250 to 300 g (9 to 10 oz). Long gray hairs, which may act as camouflage, appear on the neck, shoulders, and back soon after birth and disappear at about three months. The cubs stay hidden in a den for about eight weeks, and the mother is extremely careful to avoid attracting predators to the den. Still, she must be away for up to 48 hours while hunting, and predators often prey on her cubs while she is absent. At about eight weeks, cubs begin to accompany their mother as she hunts, and they partake in eating the meat of her kills. Nursing ends when cubs are about 4 months of age. Very young cubs begin to practice hunting through play behavior. The cubs stalk, chase, and wrestle with one another, and they will even chase prey that they know they cannot catch. Cubs do not become truly proficient hunters until they are about 24 months old. Young leave their mother at 13 to 20 months of age. Female cheetahs reach sexual maturity when they are about 24 months old, while males do not become sexually mature until they are around 30 to 36 months old. Once they reach adulthood, cheetahs may live up to 12 years in the wild and up to 16 years in zoos. Most wild cheetahs do not live as long as 12 years, however, because they are frequently preyed upon by lions, hyenas, wild dogs, and leopards. Cubs are especially vulnerable. In Tanzania's Serengeti National Park, about 90 percent of all cubs die before they are three months old, and half of these deaths are due to predation. The period between leaving the mother and reaching adulthood is also dangerous, especially for males. Half of them die during this time, largely as a result of wounds received from combat with other males over possession of territories. VI EVOLUTION Fossil evidence suggests that the cheetah may have originated about 3 million years ago in western North America. Fossils have been found in present-day Texas, Nevada, and Wyoming. Cheetahs eventually spread to Europe and Africa. Scientists believe that this early cheetah is related to the puma, which today ranges from Canada to Argentina. The early cheetah's body proportions were intermediate between those of a puma and living cheetahs. Its puma-like features included fully retractable claws and lower limbs that were not as long as those of the modern cheetah. Features shared with living cheetahs included a shortened muzzle and expanded nasal passages that facilitated oxygen uptake and distribution while running. Based on skeletal features, this early cheetah is thought to have been a faster runner than the puma but stronger and better equipped for climbing than today's cheetahs. Some scientists consider the presence of these early cheetahs on the American prairies the primary reason living pronghorns run so fast, there being no living predator in North America that can match the pronghorn in speed. VII CHEETAH STATUS In the last century the cheetah's range and numbers have steadily declined. Cheetahs were declared extinct in 1952 in India, where they were once tamed and used for hunting, and they have not been seen on the Arabian Peninsula since 1950. Cheetahs were extremely rare in North Africa by the 1960s and are now gone from that area. In sub-Saharan Africa, cheetahs exist only in low numbers except in a few places, such as Namibia, where lions and hyenas have been exterminated. Cheetahs have disappeared largely due to uncontrolled killing by humans for sport. Hunting by humans has also depleted the cheetah's preferred prey. Trade in cheetah skins, now banned in most countries, also played a role in reducing cheetah populations. Over the 20th century much open pastureland was converted into farmland. Farmers who live in cheetah habitat often kill the cats, which threaten their domestic livestock. The United States Fish and Wildlife Service lists the cheetah as endangered on its Endangered Species List. The cheetah is listed as vulnerable on the Red List of Threatened Species, compiled by the World Conservation Union (IUCN), a nongovernmental organization that compiles global information on endangered species. The cheetah is also protected by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which bans trade in cheetahs and their body parts, except for a quota of trophies (animals hunted for sport), taken in Namibia, Botswana, and Zimbabwe. In addition to the protection offered by inclusion on these lists, cheetahs are the focus of a number of conservation organizations. The Cheetah Conservation Fund (CCF), based in Namibia, is an international conservation organization that works with the Namibian government, local communities, and farmers to establish strategies to limit the conflict between farmers and cheetahs, protect cheetah habitats, and promote sustainable cheetah populations. Among the programs initiated by the CCF is the Livestock Guardian Dog Program. The CCF provides farmers with trained dogs that protect livestock from cheetahs. In another program, farmers are encouraged to inject their cattle with a harmless chemical that makes the animals taste repulsive to the cheetah. This method has also been successful at limiting cheetah attacks on livestock. The CCF has also established education programs so that farmers are more likely to contact the CCF to help them find a way to get rid of problematic cheetahs without killing them. Many farmers trap cheetahs to prevent them from attacking livestock. In some cases these traps catch cheetahs indiscriminately--many of the trapped animals do not prey on livestock. The AfriCat Foundation, also based in Namibia, works with farmers to relocate trapped cheetahs to wildlife preserves. The foundation also helps farmers develop livestock farming techniques that prevent or reduce livestock losses due to predator cheetahs. Cheetahs generally do not breed readily in captivity. To help the cheetah population in captivity, breeding programs have been established in zoos around the world. Often in the past zoo managers have had a poor understanding of the animal's lifestyle in the wild. For instance, most zoos used to house males and females together, yet in the wild, males and females avoid each other except when they come together to mate. As scientists gained a better understanding of the lifestyle habits of cheetahs in the wild, they attempted to imitate certain aspects in captivity. At the San Diego Wild Animal Park in California, for example, captive cheetahs are housed in large outdoor enclosures with expansive views. Males and females are kept separated. An unrelated male and female are reintroduced only when the female is in estrus, a period when she is receptive to mating. Mothers are provided with nest boxes and natural landscaping that offer protected areas to birth their young and protect them. As a result of these efforts, 100 cheetahs have been born in the Wild Animal Park since 1981. Zoo scientists are also working on ways to enhance cheetah breeding through assisted reproductive technologies. In several institutions in North America, ten litters of cheetahs have been produced using artificial insemination, in which sperm from the male are introduced into the reproductive tract of a female in order to enhance the opportunity for fertilization. In 1995 at the Rio Grande Zoo in Albuquerque, New Mexico, scientists used sperm collected from a wild cheetah in Namibia to fertilize eggs in a laboratory. The eggs had been taken from a captive female cheetah, and the resulting embryos were inserted into the mother's uterus; the mother then underwent a normal pregnancy. Scientists hope this method will help eliminate the need to remove cheetahs from the wild to support captive breeding programs. Scientific classification: The cheetah is a member of the cat family Felidae, in the order Carnivora, class Mammalia. Its scientific name is Acinonyx jubatus. Contributed By: John Seidensticker Susan Lumpkin Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.