Panda pregnancy watch begins

The National Zoo said Thursday that the crucial period in Washington’s annual Giant Panda pregnancy watch began this week, when experts detected the start of a rise in hormone levels in its adult female, Mei Xiang.

Once these levels start to rise, it is usually 40 to 50 days to the time when the panda either gives birth or concludes what scientists call a false pregnancy, which is common in pandas and other bears.

Mei Xiang, 11, was artificially inseminated Jan. 9 and 10 with semen from the zoo’s male panda, Tian Tian, 12. The two adults are the parents of Tai Shan, the only giant panda to be born and survive at the zoo. Tai Shan, who was born in 2005, was sent to China Feb. 4 to join a breeding program there.

Since the artificial insemination, experts have been analyzing Mei Xiang’s hormones via urine samples each week.

The zoo has tried to breed Mei Xiang for eight years. This year is perhaps the most important. The adult pandas are here on a 10-year loan from China that expires later this year.

-- Michael E. Ruane