Giant pandas are in estrus in Spring every year, and there are slight differences in different places. When the primroses in their habitats bloom, it marks the start of their estrus too. Adult male and female giant pandas gradually gather in a place and get to know each other mainly through each other’s scent and smell (by leaving scent marks and smelling marks). At the climax of estrus, they would continuously use their hearing and visual functions to croak and make sounds like birds to express their feelings.
Female pandas can mate with several competing male pandas, while one male panda tends to look for different female pandas in estrus. The estrus usually starts in late March and lasts until mid-May, mostly in mid-April, and some in January and September. The estrous cycle is once every two years, usually in the fall of that year. If the cub dies, the adult panda would be in estrus the next spring. In addition, the panda’s estrus is usually affected by the latitude, altitude and climate of the habitat.
Mating occurs mostly on the ground and sometimes on trees. Sub-adult pandas and giant pandas with weak mating skills would sometimes watch and observe nearby.
The estrus of pandas usually lasts for 12-25 days, but the climax period lasts only for 2-5 days per year, with an average of 3 days. Each mating time ranges from tens of seconds to an hour or two. The pregnancy period is about 5 months. Occasionally, twins are born in the wild, but female pandas usually only feed one cub. Twins are more common in captive populations.
During the same estrus season, a male giant panda can mate with multiple female giant pandas. Similarly, a female giant panda can also accept to mate with several male pandas. Therefore, the marriage in the giant panda world is polygamous. After they finish mating, the male and female giant pandas continue their solitary life. The pregnancy, childbirth and child rearing are done by the female giant panda alone.
Before her delivery, the female panda would look for roots and burrows in empty trees to give birth to her cub. Generally, it has to spend three months in and around this shelter and carefully cares for the cubs with its big palms.
A few days to a month after the cub is born, the mother panda would leave the cub alone in the hole or the tree hole before looking for food outside. The female panda sometimes leaves for 2 days or more. This does not mean that it has abandoned the cub, but it is just a natural part of the process of raising it. The cub starts eating bamboo around 12 months, but before that, they are totally dependent on their mother. The mortality of panda cubs in the wild is lower than that in captivity, about 40%.