CHENGDU, Feb. 17 (Xinhua) -- Better hearing and stronger hind legs would help giant pandas, an endangered and sex-shy species, to mate and conceive, panda experts in southwest China's Sichuan Province said Thursday.
But for a pair of panda bears currently living in Taiwan, breeding experts have to resort to artificial insemination to increase the chance for them to have a cub, hopefully between August and October.
"Panda pairs should be trained properly to recognize the unique, 'baa-ing' like bleating sounds from their spouse on heat," said Huang Yan, a panda expert with China Giant Panda Protection and Research Center in Wolong, Sichuan.
Meanwhile, adult pandas should exercise more to gain strength in their hind legs, which are crucial during mating, said Huang.
Huang was in Taipei early this month to provide technical assistance to Taipei Zoo, where panda couple Tuan Tuan and Yuan Yuan were expected to breed.
The two Wolong-born pandas, whose names when put together mean "reunion," arrived in Taipei in 2008 as gifts from the Chinese mainland.
Both six years old, the pair became sexually active at the end of January. As Tuan Tuan, the male panda, had shown no interest in mating, zoo workers collected his sperm with the hope of artificially impregnating Yuan Yuan.
"It's a common practice to try artificial insemination while also giving the pandas a chance to breed naturally to increase the chance of pregnancy," said Zhang Hemin, head of the Wolong center.
Pandas' once-a-year estrus cycle lasts only two weeks and the success rate of natural breeding is very low.
"It would be normal for Tuan Tuan and Yuan Yuan to fail to naturally produce a cub because they had just reached maturity and lacked sexual experience," said Huang Yan.
If artificial insemination proved successful, Yuan Yuan would be expected to give birth in summer or fall, as the average pregnancy for pandas lasts for 120 to 150 days, said Huang.
Huang said Yuan Yuan now needed rest and nutrition and her physical situation should be monitored closely. "We are ready to fly back to Taipei at any time if there is anything abnormal or if Yuan Yuan is found pregnant."
It is hard to confirm a panda's pregnancy, he said. "It's impossible to tell from appearance," he said.
Even by using ultrasound, it is difficult to tell until 15 days before delivery.
Wolong's panda experts are also waiting for good news from the Smithsonian National Zoological Park in Washington D.C., the United States, after they tried artificial insemination in late January on Mei Xiang, who has lived there with her spouse Tian Tian since Dec. 6, 2000.
The couple have not produced a cub since the 2005 birth of Tai Shan, who returned to China last year.
Experts say pandas can conceive before they turn 20 years old, and the success rate is often higher for experienced couples.
At the Wolong center's Bifeng Gorge base in Ya'an City, near the provincial capital Chengdu, most pandas are yet to enter the estrus cycle.
Tang Chunxiang, the center's senior vet, expected massive breeding to start in late February or early March.
Giant pandas are among the world's most endangered animals. About 1,590 pandas live in the wild in mountains of northern Sichuan and neighboring Shaanxi and Gansu provinces.
Another 300 are living in captivity at worldwide zoos. Wolong center alone has 165 pandas and the Chengdu base, another major panda research body, has 98.