Female pandas normally are in heat only two or three days a year, and Mei Xiang "is not there yet," Stevens said. At 3 1/2 years old, she may not be ready this year. Tian Tian, 4 1/2, is breeding age.

And at the time of writing the panda, named Ding Ding, was still visible to the public in its enclosure. Ding Ding is a female panda born on August 30, 2015 at Chongqing Zoo, with pedigree number 982.

The female cub is the third for mom and dad and is part of the Red Panda Species Survival Plan. The zoo says the plan helps maintain genetic diversity within red panda populations in accredited zoos.

The "black-and-white rock star" of the Smithsonian's National Zoo, female panda Mei Xiang, is recovering Monday after being artificially inseminated with up to 800 million sperm.

The female cub is the third for mom and dad and is part of the Red Panda Species Survival Plan. The zoo says the plan helps maintain genetic diversity within red panda populations in accredited zoos.