Smithsonian National Zoological Park l Friends of the National Zoo



Winter 2008-2009 Updates

January 18: Panda Mating Season Begins Early

On January 9, the National Zoo’s animal care team noticed increased interaction between our adult giant pandas, female Mei Xiang and male Tian Tian, including distinctive vocalizations that are associated with mating season. Staff immediately began monitoring Mei Xiang’s hormone levels in her urine, which allows them to predict the exact moment of ovulation.

Throughout the day on January 15, Mei and Tian attempted to mate. Zoo staff carefully observed the panda’s activities and because competent mating did not occur, Zoo scientists and veterinarians performed two nonsurgical artificial insemination procedures beginning on January 17. Both pandas were anesthetized, allowing Zoo scientists to collect sperm from Tian Tian and insert it directly into Mei Xiang’s uterus.

Zoo staff separated Mei and Tian prior to performing the artificial insemination. They will remain separated for the next few months, until Mei either delivers a cub, or until Zoo scientists determine 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 will monitor Mei Xiang’s hormone levels and perform ultrasounds to determine whether or not she is pregnant.

Giant pandas have one very brief mating season each year, with only about one day a year in which conception can occur. For the last six years, Mei Xiang has typically ovulated in March or April. This year’s early start is unusual, but due to the expertise of National Zoo staff, they were able to identify signs of this early reproductive activity and mobilized quickly for a possible artificial insemination. There is no conclusive study that indicates the cause of 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 knew light on what triggers the reproduction of this endangered species.

January 15

Today some web cam viewers and Zoo staff saw something we weren't expecting until later this year—an attempt at mating! Mei Xiang has shown some behavioral and hormonal signs that she was nearing estrus, nearly two months earlier than the earliest date she has begun estrus, but her hormone levels have not peaked. Every time our bears do something that surprises us—and when they do what we expect—we learn something new, so we appreciate these opportunities to gain insight into these fascinating animals. We will post more information soon.

December 25

The sunrise was beautiful this morning. The sky went from midnight blue, with the tiniest sliver of a moon, to bold strokes of greys, and oranges added on, at dawn. The pandas are all up and ready for their first bamboo meal, at this time of day. Their anxiety to eat makes for fleet feet when preparing their morning meal. Care must be taken by the keepers in case the morning mist has turned into an icy glaze in the yards. The pandas, even demure Mei Xiang, bulldoze their way out and straight to the first pile they find. Gone are the preferences from a mere month ago. Golden bamboo is delicious again. The pandas also are now requesting their second feeding as early as 10 a.m. After some serious attention to the bamboo it is time to wander and play. Playing in trees is the activity of the season. With their new found energy pandas may be seen playing or wandering just about everywhere now.

This is the time of year that the nutrition department staff has to work extremely hard to keep our shed full of bamboo. They do this on top of all the work it takes to feed all of the other zoo animals. The work load of the keeper staff also increases, not only in distributing the bamboo, but also picking up all of the feces! Pandas digest only 20 to 25 percent of what they consume and can produce up to 40 fibrous, green or yellow (depending on what part of the plant they have eaten) large, baked potato sized droppings. When the pandas shred and eat the culm or stalk, all of the remainder must be cleaned up. Only one look at their beautiful faces contentedly munching bamboo makes our morning, and every morning of the year, like Christmas.

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