A female panda bred in captivity and released into a nature reserve in Southwest China has mated with a wild panda, in a breakthrough for cultivation of the species, Chinese researchers announced on April 21.

Staff with the China Conservation and Research Center for the Giant Panda (CCRCGP) said that sound captured by a voice recorder on female giant panda Caocao’s collar confirmed that she had mated in Wolong National Nature Reserve in Sichuan province on March 23.

The recording was part of a trial aimed at encouraging captive-bred pandas to breed with wild ones.

It is notoriously difficult to get pandas to breed. According to Zhang Hemin, deputy director of the CCRCGP, China’s captive panda breeding program has successfully grown the population but ensuring the pandas’ genetic vitality and diversity under artificial propagation remains a challenge.

The center hopes that more of its captive-bred giant pandas can mate with wild companions in order to bring new blood into their group. Most of China’s 471 captive pandas have succeeded in mating via artificial intervention in the past few years.