Smithsonian National Zoological Park l Friends of the National Zoo



Ultrasound Reveals Two Andean Bear Cubs; Staff Cautiously Optimistic For a Successful Birth

Good news comes in small packages. In this case, it came in the form of two small blips on an ultrasound screen. In early November, Zoo veterinarians and keepers began to suspect that Billie Jean, our female Andean bear, might be pregnant. An ultrasound 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.

Andean Bears

Billie Jean is acting very much as she did the last time she gave birth, according to her keepers. Her appetite has decreased, she’s built a nest (in a den this time, not a tree) and she is beginning to choose to stay inside even when she’s given access to the outdoors, which is rare for her. These signs all point toward an impending birth.

Billie Jean's Ultrasound

While keepers and veterinarians are encouraged by their observations, they describe their excitement as 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. And, like other carnivore mothers, there is a possibility Billie Jean could harm or kill her cubs after birth. However, Zoo staff are hopeful that she will exhibit the same maternal instincts she did in January 2010, when she proved to be an excellent mother to Bernardo and Chaska. Newborn cubs weigh 10 to 18 ounces at birth, and they are practically bald, toothless and blind.

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.

Billie Jean

Billie Jean arrived at the National Zoo in 2008 and immediately gained a reputation as an active, agile bear. Since her arrival keepers have worked to build trust and train her. This training is important because it 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 positively rewarded with her favorite foods, peanuts and honey.

The Andean bear population in human care has experienced a lull in the last six years. If Billie Jean does give birth to live young, they will be the only surviving Andean cubs in a North American Zoo since she gave birth to two cubs, a boy Bernardo and a girl Chaska, on January 14, 2010. Coincidentally, the last surviving Andean bear born in North America before that was their mother, Billie Jean. Billie Jean’s pregnancy taught the National Zoo much valuable information about reproduction and cub development, and we’re learning even more. We will share this information with the Association of Zoos and Aquariums for the benefit of other institutions that exhibit and want to breed this species.

All of Billie Jean’s cubs share the same father, Nikki, who was humanely euthanized in August of 2012 after a year-long battle with squamous cell carcinoma (cancer). Natural breeding between Nikki and Billie Jean took place in April.


Nikki himself has a fascinating story. When he came to the Zoo in 2007 he was accustomed to eating all sorts of sweets, and he was grossly overweight. Keepers and vets work together to determine an animal’s body condition. With Nikki, they had a hard time feeling their way through the fat to even find his bones. But, just like humans, animals can’t lose weight too rapidly, so our nutritionist worked with the vets and keepers to lay out a very slow, but steady, weight loss plan for him. They set a target weight based on historical records of what a male Andean bear should weigh. As they slowly inched his weight downward, everyone kept a close eye on how he looked and how he behaved. As he lost weight, he became more active, climbing over the trees and logs in his yard and acting much like an Andean bear would in the wild.

It took more than a year, but Nikki lost a whopping 150 pounds and finally achieved what the vets and nutritionists deem his healthiest weight. As this happened, his keepers saw an increase in his activity level, and started to see him exhibit many more natural behaviors. They started to see him turning over rocks in his yard looking for and then eating insects.

As he reached his ideal weight, he joined young female Andean bear Billie Jean in the yard. They seemed to take to one another’s company right away. He showed her how to swim, and she taught him how to climb. Andean bears are typically arboreal, but Billie Jean is remarkably so, even going so far as to build herself a nest in a tree, natural Andean bear behavior that’s not usually seen in a zoo setting. Billie Jean also learned Nikki’s appreciate for a wider variety of food, albeit in moderation now.

Keepers and zoo fans alike hope that Nikki’s legacy will continue in the form of strong, healthy cubs born this winter. Beyond than being a heartwarming story, though, such a birth would be important for the future of Andean bears in North America, as Nikki’s genes are particularly valuable.