Panda Rebuffs Tests to Check For Pregnancy

All seemed quiet on the panda pregnancy front yesterday, although Mei Xiang, the possibly pregnant giant panda, would not cooperate with ultrasounds attempted Friday and Tuesday, the National Zoo said.

She did the same thing right before her cub, Tai Shan, was born in 2005, but the zoo's panda experts don't know what, if anything, to make of that. The ways of panda reproduction are capricious and frustrating, and with Panda-nation awaiting an outcome, one zoo official referred to Mei Xiang as "this dang bear."

The experts are closely watching Mei Xiang's hormone levels this week. The decline in her hormone level indicates that her reproductive cycle is coming to a close, and she was put on 24-hour-a-day video pregnancy watch Saturday night.

When the hormone progestin drops to its base line levels, the real hand-wringing starts. The panda will either deliver a tiny cub within a few days, or the zoo will declare a false pregnancy, which is common in pandas.

The Panda House remains closed until further notice, although zoo goers can see the two male pandas outdoors from early morning until midafternoon every day.

Scientists artificially inseminated the 10-year-old Mei Xiang with semen from the zoo's male giant panda Tian Tian, 11, on Jan. 17, after they realized that she had come into heat three months earlier than usual.

Since then, the zoo has conducted weekly and biweekly hormone tests, using daily urine samples from Mei Xiang. That's a tedious process in which urine must be collected from her enclosure, then driven to the zoo's Conservation and Research Center in Front Royal, Va., for analysis.

Veterinarians are also trying to do biweekly ultrasounds to look for evidence of a fetus. When she has cooperated, they have not seen anything, although panda fetuses do not start developing until the last weeks of gestation.

This is the eighth year the zoo has tried to breed Mei Xiang.