The giant panda or Ailuropoda melanoleuca is a species in danger of extinction--there are only about 1,600 in the wild and another 300 or so in zoos, and they are on the World Conservation Union's Red List of Threatened Animals. They live in a few mountain ranges in central China. Once thought to be members of the raccoon family, it’s now known that giant pandas are bears. They are different from other bears not only in their dietary choice of bamboo instead of a wide variety of meats and vegetation, but in how they reproduce.
Male giant pandas mate with the female and that is the end of their parental duties. The female rears the cubs all by herself. Giant pandas are mostly solitary animals, but the National Zoo states that small groups of pandas will meet on occasion where no mating is involved.
The female panda cares for her cub until it is 18 months or 3 years old, but she only nurses it with milk until it is 8 to 9 months old. For the first two months, she physically keeps in contact with the cub because the cub cannot keep itself warm enough. She helps stimulate the cub's bowels and bladder by licking under the tail until the cub can urinate and defecate on its own. She helps protect and play with the cub as well as helping the cub find food. She may also teach the cub about wild panda social behaviour and how to scent mark and call to other pandas.
Because it takes so much of the mother’s time and energy to raise one cub and because her bamboo diet makes less and weaker milk in comparison with other bear species, if a female panda gives birth to more than one cub, she must select one to live and kill the rest. In captivity, the other cubs can be taken away from the mother and reared by hand.
The female panda does not breed the entire time she is taking care of her cub. In this way, she can devote more of her energies into making sure each cub has the best chance at surviving before it wanders off on its own. This means that female pandas breed very rarely. The National Zoo estimates that a fertile female panda, living to her 20s is only capable of having five to eight cubs in her lifetime.
A female panda gives birth to cubs that are only 1/900th her size. The cub is mostly naked, barely able to move, blind and deaf. The cub will not be able to see until it is about five weeks old. Perhaps pandas had to give birth to such undeveloped young sometime between days 95 to 160 because their bodies could not manage a longer gestation. Bamboo is plentiful but poor in nutrients.