CHENGDU, May 22 (Xinhua) -- A panda in southwest China has given birth to the first set of captive-bred twins this year.

Sichuan Province's Chengdu panda research base announced Monday that the male twins were born on April 24. They have passed the critical first month of life and are very healthy.

The cubs weighed about 110 grams at birth and have grown up to 852 grams and 844 grams respectively in their first month, according to the base.

Staff bottle fed the cubs with stored milk from other female pandas for the first nine days until the mother panda, ZhiZhi, could breastfeed them.

Pandas are an endangered species due to their extremely low fertility rates in the wild. In captivity, they often give birth to twins and sometimes even triplets.

There are fewer than 2,000 pandas in the wild, mostly in Sichuan. More that 400 currently live in captivity.