The 2009 giant panda mating season began Thursday, Jan. 15 at the Smithsonian’s National Zoo. Female Mei Xiang (may-SHONG) and male Tian Tian (tee-YEN tee-YEN) attempted to mate throughout the day Thursday. For the past six years, Mei Xiang has typically ovulated in March or April.
Zoo staff carefully observed the pandas’ activities and, because competent mating did not occur, Zoo scientists and veterinarians performed two nonsurgical artificial inseminations Jan. 17. Both pandas were anesthetized, allowing Zoo scientists to collect semen from Tian Tian and insert it directly into Mei Xiang’s uterus.
Giant pandas have one very brief breeding season per year, with only a day or two of actual mating. This year’s early start is unusual, but the National Zoo staff’s expertise enabled them to identify signs of this early reproductive activity and mobilized for a possible artificial insemination.
On Jan. 9, the Zoo’s animal care team noticed increased interaction between Tian Tian and Mei Xiang, including distinctive vocalizations that are associated with mating season. Staff immediately began monitoring Mei Xiang’s hormone levels in her urine, which allowed them to predict the exact moment she had ovulated. Timing is crucial—female giant pandas only have about one day a year in which conception can occur.
There is no conclusive study that indicates what causes panda ovulation. Although scientists know that giant pandas mostly breed in late winter to early spring, it is not known if the onset of reproductive activity is triggered by increasing day length, temperature or some other environmental factor. This year’s unusually early onset of reproductive activity should allow Zoo scientists to shed new light on what triggers the reproduction in this endangered species.
Zoo staff separated Mei Xiang and Tian Tian before performing the artificial insemination. They will remain separated for the next few months, until Mei Xiang either delivers a cub, or Zoo scientists determine that she is not pregnant. Keeping the pandas separated will reduce the risk of increased stress-hormone levels in Mei Xiang, which could jeopardize a developing embryo. Panda gestation typically lasts from 90 to 185 days. Veterinarians and scientists will monitor Mei Xiang’s hormone levels and perform ultrasounds to determine if she is pregnant.
Last year, scientists artificially inseminated Mei Xiang but she did not give birth. Mei Xiang and Tian Tian have produced one cub, Tai Shan (tie-SHON), who was born July 9, 2005 as a result of artificial insemination.