Atlanta's giant panda placed on birth watch

ATLANTA (AP) - Lun Lun, Zoo Atlanta's female giant panda, has been removed from exhibit and placed on a 24-hour birth watch, though zoo officials still aren't sure she is pregnant.

There are no pregnancy tests for giant pandas. In March, zoo officials announced that Lun Lun had been artificially inseminated, and that if she was pregnant she would give birth by August.

''She could give birth at any time - if she's pregnant,'' Zoo Atlanta spokeswoman Jacqueline Petty said Monday.

Pandas may experience symptoms such as loss of appetite and enlarged mammary glands without being pregnant, which makes it difficult to predict the panda will give birth until the last two to four weeks of pregnancy.

Petty said recent symptoms shown by Lun Lun make it more likely she indeed is pregnant.

''Her activity level and appetite began to decrease even more,'' Petty said. ''We noticed hormonal changes which are further symptoms.''

Lun Lun and the zoo's male giant panda, Yang Yang, have not mated.

The National Zoo's female panda, Mei Xiang, gave birth earlier this month. Only two giant panda cubs born in the U.S., both at the San Diego Zoo, have lived to adulthood.