The panda (Ailuropoda melanoleuca, lit. "black and white cat-foot"), also known as the giant panda to distinguish it from the unrelated red panda, is a bear native to central-western and south western China. It is easily recognized by the large, distinctive black patches around its eyes, over the ears, and across its round body.
Adults measure around 1.2 to 1.8 m long, including a tail of about 13 cm, and 60 to 90 cm tall at the shoulder. Males can weigh up to 160 kg. Females (generally 10–20% smaller than males) can weigh as little as 75 kg, but can also weigh up to 125 kg. Average adult weight is 100 to 115 kg.
Two subspecies of giant panda have been recognized:
The giant panda has a body shape typical of bears. It has large molar teeth and strong jaw-muscles for crushing tough bamboo.
The giant panda's paw has a "thumb" and five fingers; the "thumb" - actually a modified sesamoid bone - helps it to hold bamboo while eating.
The giant panda's tail, measuring 10 to 15 cm, is the second-longest in the bear family. (The longest belongs to the sloth bear.)
The giant panda typically lives around 20 years in the wild and up to 30 years in captivity. The oldest captive, a female named Ming Ming, had a recorded age of 34.
It has black fur on its ears, eye patches, muzzle, legs, arms and shoulders. The rest of the animal's coat is white. Although scientists do not know why these unusual bears are black and white, speculation suggests that the bold coloring provides effective camouflage in their shade-dappled snowy and rocky habitat. The giant panda's thick, wooly coat keeps it warm in the cool forests of its habitat.
In the wild, the giant panda is a terrestrial animal and primarily spends its life roaming and feeding in the bamboo forests of the Qinling Mountains and in the hilly Sichuan Province. Giant pandas are generally solitary, and each adult has a defined territory, and a female is not tolerant of other females in her range. Pandas communicate through vocalization and scent marking such as clawing trees or spraying urine. They are able to climb and take shelter in hollow trees or rock crevices, but do not establish permanent dens. For this reason, pandas do not hibernate, which is similar to other subtropical mammals, and will instead move to elevations with warmer temperatures.
Social encounters occur primarily during the brief breeding season in which pandas in proximity to one another will gather. After mating, the male leaves the female alone to raise the cub.
Though the panda is often assumed to be docile, it has been known to attack humans, presumably out of irritation rather than aggression.
Initially, the primary method of breeding giant pandas in captivity was by artificial insemination, as they seemed to lose their interest in mating once they were captured. Only recently have researchers started having success with captive breeding programs, and they have now determined giant pandas have comparable breeding to some populations of the American black bear, a thriving bear family. The current reproductive rate is considered one young every two years.
Giant pandas reach sexual maturity between the ages of four and eight, and may be reproductive until age 20. The mating season is between March and May, when a female goes into estrus, which lasts for two or three days and only occurs once a year. The gestation period ranges from 95 to 160 days.
If twins are born, usually only one survives in the wild. The mother will select the stronger of the cubs, and the weaker will die. The mother is thought to be unable to produce enough milk for two cubs, since she does not store fat. The father has no part in helping raise the cub.
When the cub is first born, it is pink, blind, and toothless, weighing only 90 to 130 grams, or about 1/800th of the mother's weight. One to two weeks after birth, the cub's skin turns gray where its hair will eventually become black. A slight pink color may appear on cub's fur, as a result of a chemical reaction between the fur and its mother's saliva. A month after birth, the color pattern of the cub's fur is fully developed. Its fur is very soft and coarsens with age. The cub begins to crawl at 75 to 80 days; mothers play with their cubs by rolling and wrestling with them. The cubs are able to eat small quantities of bamboo after six months, though mother's milk remains the primary food source for most of the first year. Giant panda cubs weigh 45 kg at one year, and live with their mothers until they are 18 months to two years old. The interval between births in the wild is generally two years.
Despite its taxonomic classification as a carnivoran, the giant panda's diet is primarily herbivorous, consisting almost exclusively of bamboo. However, the giant panda still has the digestive system of a carnivore, as well as carnivore-specific genes, and thus derives little energy and little protein from consumption of bamboo. The limited energy input imposed on it by its diet has affected the panda's behavior. The giant panda tends to limit its social interactions and avoids steeply sloping terrain to limit its energy expenditures.
Two of the panda's most distinctive features, its large size and round face, are adaptations to its bamboo diet. Panda researcher Russell Ciochon observed: “[much] like the vegetarian gorilla, the low body surface area to body volume [of the giant panda] is indicative of a lower metabolic rate. This lower metabolic rate and a more sedentary lifestyle allows the giant panda to subsist on nutrient[-]poor resources such as bamboo.” Similarly, the giant panda's round face is the result of powerful jaw muscles, which attach from the top of the head to the jaw. Large molars crush and grind fibrous plant material.
Pandas eat any of 25 bamboo species in the wild.
Because of the synchronous flowering, death, and regeneration of all bamboo within a species, the giant panda must have at least two different species available in its range to avoid starvation. While primarily herbivorous, the giant panda still retains decidedly ursine teeth, and will eat meat, fish, and eggs when available. In captivity, zoos typically maintain the giant panda's bamboo diet, though some will provide specially formulated biscuits or other dietary supplements.