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Contrary to popular belief, Giant pandas do not reproduce slowly. Studies have shown that wild pandas reproduce as well as North American brown bears.[14] A female panda may have 2-3 cubs in a lifetime, on average. Growth is slow and pandas may not reach sexual maturity until five to seven years of age. The mating season usually takes place from mid-March to mid-May. During this time, two to five males can compete for one female; the male with the highest rank gets the female. When mating, the female is in a crouching, head-down position as the male mounts from behind. Copulation time is short, ranging from thirty seconds to five minutes, but the male may mount repeatedly to ensure successful fertilization.
The whole gestation period ranges from 83 to 163 days, with 135 days being the average. Baby pandas weigh only 90 to 130 grams (3.2 to 4.6 ounces), which is about 1/900th of the mother’s weight. Usually, the female panda gives birth to one or two panda cubs. Since baby pandas are born very small and helpless, they need the mother’s undivided attention, so she is able to care for only one of her cubs. She usually abandons one of her cubs, and it dies soon after birth. At this time, scientists do not know how the female chooses which cub to raise, and this is a topic of ongoing research. The father has no part in helping raise the cub.
When the cub is first born, it is pink, furless and blind. It nurses from its mother's breast 6 to 14 times a day for up to 30 minutes at a time. For three to four hours, the mother may leave the den to feed, which leaves the panda cub defenseless. 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 the panda'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. A cub's fur is very soft and coarsens with age. The cub begins to crawl at 75 to 90 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 (99.2 pounds) 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.
Breeders and biologists often experience difficulty in inducing captive pandas to mate, threatening their already diminished population. This problem may stem from the captive bears' lack of experience. In an attempt to remedy this, some keepers in China and Thailand have shown their subjects videos containing footage of mating pandas. [15] In some cases, the bears have been sufficiently stimulated from the videos to engage in reproductive activity. It is not likely that the animals actually learn mating behaviors from the video; rather, scientists believe that hearing the associated sounds has a stimulating effect on the bears exposed to it.