As the world celebrated the pregnancy news from Buckingham Palace earlier in the week, staff at the Smithsonian's National Zoo were making preparations for their own highly anticipated birth: Andean bear cubs. Zoo veterinarians have conducted weekly ultrasounds since Nov. 6 on 6-year-old Billie Jean. The first revealed two small, distinct amniotic sacs; three subsequent ultrasounds have shown fetal growth and development, heightening hopes that Billie Jean may give birth for the second time.
While keepers and veterinarians are encouraged by their observations, they are cautiously optimistic. Like all bear species, Andean bears can resorb one or both fetuses at any stage of the pregnancy, resulting in only one or no cubs. Zoo staff are hopeful that Billie Jean will exhibit the same maternal instincts she did in Jan. 2010, when she proved to be an excellent mother to Bernardo and Chaska.
All of Billie Jean's cubs share the same father, Nikki, who was humanely euthanized in August after a yearlong battle with squamous cell carcinoma (cancer). Natural breeding took place in April.
It would not only be a heartwarming story if Nikki's legacy were to continue, said Craig Saffoe, curator of Great Cats and Bears. It will also be a huge conservation success as his genes are extremely valuable to the North American Species Survival Plan for Andean bears. We learned so much about reproduction and cub development from her first litter, and we are eager to learn more and use that knowledge to benefit the species as a whole.
Keepers have worked to build trust and train Billie Jean since she arrived at the National Zoo in 2008. This training allows keepers and veterinarians to observe her at a close range and perform ultrasounds on her abdomen. The Zoo's metal shop crafted a short, sturdy chair and attached it to Billie Jean's enclosure. When keepers give the cue, Billie Jean voluntarily sits in the chair and reaches for a bar above her head, thereby exposing her belly and giving veterinarians direct access to her abdomen. If she chooses to participate, she is rewarded with her favorite foods, peanuts and honey.
Billie Jean's behavior is similar to what we observed the last time she had a successful delivery, said Karen Abbott, an animal keeper. She's been eating less of her regular diet, she's nest-building and she's starting to choose to stay in her den even when offered outdoor access. All these signs tell us she's gearing up to give birth soon.
The Andean bear population in human care has experienced a lull in the past six years. If Billie Jean does give birth successfully, the cubs will be the only surviving Andean cubs in a North American Zoo since her first cubs, Bernardo and Chaska, were born. The last surviving Andean bear born in North America before that was their mother, Billie Jean. The information gathered from the National Zoo's Andean bears will be shared with the Association of Zoos and Aquariums for the benefit of other institutions that exhibit and want to breed this species.
Andean bears—also known as spectacled bears—are listed as vulnerable on the International Union for Conservation of Nature's Red List of Threatened Species, and it is estimated that there are only 2,000 left in their natural habitat. They are South America's only bear species, and as their name suggests, they live in the Andes mountain range from western Venezuela south to Bolivia, with sightings reported from eastern Panama and extreme northern Argentina. Newborn cubs weigh 10 to 18 ounces at birth, and they are practically bald, toothless and blind.
During Billie Jean's denning period, Zoo visitors can see 2-year-old Chaska on exhibit near the lower entrance to American Trail, weather permitting. To follow Billie Jean's progress, watch her on the Zoo's live webcam, read updates from the Zoo's Andean bear keepers and check for news on the Zoo's Twitter feed and Facebook page with the hashtag #cubwatch.
Photo credit: Smithsonian's National Zoo
In this photo: Andean bear Billie Jean's ultrasound revealed two small, distinct amniotic sacs; three subsequent ultrasounds have shown fetal growth and development, heightening hopes that Billie Jean may once again give birth.