A panda cub was born Monday in southwest Sichuan Province, which panda researchers said is an unusual time for the cuddly bears to give birth.

Pandas are known for being sexually inactive and cubs are often born between July and September, not late autumn.

Sixteen-year-old Fei Fei gave birth to a healthy cub at around 2 p.m. Monday at a semi-wild breeding base of the Wolong Giant Panda Protection and Research Center, the center said in a press release Tuesday.

Panda researchers at the center said they could not see clearly whether the cub was male or female, as Fei Fei, who has given birth to five other cubs, was a skilled mother and kept the new cub at her side at all times.

The new cub was born in a near-wild environment in Bifeng Gorge, a nature reserve in the city of Ya'an, at a panda research base affiliated to the Wolong center.

Its birth and breeding were monitored by panda keepers only through video camera lens, said Tang Chunxiang, an expert with the center.

Tang said panda keepers will watch Fei Fei and her cub closely as the tough natural condition in the mountains, where the high temperature is around 10 degrees Celsius, pose challenges. It's Fei Fei's first time to raise a cub in the semi-wild environment.

Fei Fei, born in 1995, received wild training this year. One of her cubs was born on Aug. 8, 2008, the day the Beijing Olympic Games opened, and was named "Ao Yun," meaning "Olympics."

China's plan to save the endangered species by releasing captive-bred pandas into the wild began in 2003, with Xiang Xiang, a male cub being trained to survive in the wild.

Xiang Xiang was released into the wild in 2006, but was found dead 10 months later in a remote corner of Wolong. He had apparently been attacked by wild pandas native to the place.

The program was resumed last year at two panda research centers in Wolong and Chengdu.

This year, seven cubs have been born under the wild program at Wolong center alone.

Most giant pandas in captivity are not good breeders. Only 24 percent of females in captivity give birth.