CHENGDU, Aug. 31 (Xinhuanet) -- Hua Mei, China's first overseas-born panda (born in the San Diego Zoo in the United States) is likely to become a mother soon, say experts.

    Senior engineer Huang Yan said the lady panda has shown antepartum symptoms including loss of appetite and sleeping more than usual. Huang is an associate chief engineer of the Wolong Panda Conservation Center in the bamboo forests of southwest China's Sichuan province.

    According to Huang, a female panda will show symptoms usually two weeks before giving birth, eating less, building a nest or holding something in its arms. And days before delivering, the panda will stop eating and will move very little. He believes that Hua Mei is expecting, but warned that "it isn't 100 percent sure, because accurate diagnosis of pandas' pregnancy and bearing are difficult."

    Hua Mei, born in 1999 in the US zoo, returned to China last February. Turning five years old this Aug., Hua Mei is the first Giant Panda to be born and survive in the western hemisphere since1990.

    Hua Mei mated with another panda, Ling Ling, on May 2. She later received artificial fertilization four times.

    A female panda normally becomes sexually mature at four to five years old, and pandas in captivity at the Wolong Conservation Center are usually in heat from March to May. They only get pregnant once a year, giving birth to one or two cubs at a time.

    Researches show that giant pandas have a relatively low fertility rate, which is tremendously impaired in captivity. For long periods, over 60 percent of adult male giant pandas in protection areas or zoos lacked any sexual desire. Only 10 percentof them are capable of natural mating. Only 30 percent of female giant pandas become pregnant and give birth.

    According to Huang, staff could only estimate a period in which the birth is likely to happen, and can do nothing but wait.

    Pregnancy determination has been a thorny problem for scientists. Hormone or ultrasonic examinations, which are frequently adopted to determine whether an animal is pregnant, do not work on pandas and sometimes the examination results are proven to be incorrect, Huang said.

    Panda gestation lasts 83 to 181 days.

    Hua Mei, meaning "China-America," was the cub of Bai Yun and Shi Shi, a panda couple leased by China to the San Diego Zoo, California, U.S. in 1996 as part of a 12-year research cooperation program between the two nations.

    Under the cooperation contract, cubs of pandas abroad belong to China and should be returned after they turn three. She came back to Wolong this February, where she joined her father, Shi Shi, who returned last year. Bai Yun, Hua Mei's mother, remained in San Diego with another male panda, Gao Gao, and their one-year-old son,Mei Sheng, which means "born in America."

    Pandas are among the world's most endangered wildlife. Statistics from the State Forestry Administration released in thisJune show the number of pandas in the wild in China has risen by more than 40 percent from 1,110 in the 1980s to 1,590 nowadays, while a total of 161 are in captive breeding programs worldwide.

    However, while the panda population has increased, the animal's existence is menaced by loss of habitat and a low rate of reproduction. Also, groups of pandas live far from each other, making breeding even more difficult.

    The Wolong center, founded in 1963, is the largest panda reserve in China. It has an area of 200,000 hectares and is world-renowned as the home for pandas. Enditem