Any human mother of multiples knows it's hard to raise two or more children of the same age at the same time. And it's true for other mammals, too.
"Nearly half of all giant panda births in zoos and research stations result in twins," Don Lindburg says. Lindburg is the leader of the giant panda research team at the San Diego Zoo.
"Taking care of tiny infants is an awesome chore, and mother pandas usually can't handle two," Lindburg says.
"Every newborn panda is important," says Lindburg "After giant pandas have grown to adulthood, some of the captive-born bears could be released into the mountainous wilds," he says. Those that mate and give birth to more cubs will help rebuild China's perilously small population of wild pandas.
At China's Wolong facility, caregivers are helping make the mother's situation more "bear-able." They gently remove one of the twins, keeping it warm and well fed for a week before trading it for the cub's brother or sister.
The cubs continue to be swapped for months, until they can eat solid foods and no longer need to nurse.
Bamboo, apples, carrots, and biscuits are added to the diet of mother's milk when the cubs are about seven months old. By adulthood, the pandas will eat fresh stems, shoots, and leaves of wild bamboo plants.
- In five years female cubs will be mature enough to give birth to cubs of her own.
- Sixteen pandas were born in Wolong Nature Reserve in 2005.