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Polar bear, a species threatened with extinction

The polar bear has become an icon for global warming in political and public arenas. Because sea ice is an essential component of the polar bears’ ecosystem, a change in its distribution and longevity due to global warming could profoundly affect the species’ future. Because of this impending threat of the loss of sea ice, polar bears were listed as threatened under the U.S. Endangered Species Act in 2008. Zoos are strategically breeding this species in efforts to develop a self-sustaining captive population while employing these charismatic ambassadors to educate visitors about global warming and wildlife conservation.

CREW is Saving Species with Science®

Through the use of assisted reproduction and sound scientific technologies, CREW scientists in the Animal Research Division are Saving Species with Science®. CREW’s research results broaden our knowledge and understanding of animal biology, increases genetic diversity among captive populations, connects captive and wild populations and conserves imperiled animals in their natural environment.

Predicting Polar Bear Pregnancy

High neonatal mortality and poor overall reproductive success in captive polar bears threaten the genetic health and long-term viability of this species in zoos. Furthermore, population management by the Species Survival Plan (SSP) is particularly challenging because of the pronounced seasonality of this species and associated timing of breeding and cubbing seasons. CREW scientists discovered a method for noninvasively monitoring the reproductive status of polar bears through fecal hormone analyses and have recently completed a nationwide project studying polar bears in breeding situations.

The results of this project have led to a better understanding of the species’ basic biology, and from a more practical perspective, a method for possible pregnancy diagnosis in polar bears. Specifically, the results of this study will 1) assist the SSP in its population management decisions so that females with greater chances of becoming pregnant are paired with genetically diverse males, 2) facilitate zoos’ efforts to manage their bears for reproductive success by making sure potentially pregnant bears are appropriately denned up and not disturbed during the cubbing season, and 3) improve the overall welfare of captive bears by ensuring that non-pregnant bears are not maintained in dens when they would rather be outside swimming all winter.

CREW and Seneca Park Zoo Pioneer Assisted Reproduction Techniques in Polar Bears

Despite two breeding seasons together, Aurora and Zero, two behaviorally compatible polar bears at the Seneca Park Zoo in Rochester, NY, had not figured things out. Aurora, a 22-year old female, produced three litters with her previous mate. Zero, a 970 lb male, had been housed with multiple females during his lifetime but never sired any cubs. Despite multiple attempts to breed, Zero appeared to suffer from ‘alignment issues’. Because Aurora’s fertile years are nearing an end, Seneca Park staff requested some high tech help from CREW to increase their chances for cubs in 2012. CREW scientists have been monitoring Aurora’s fecal hormone concentrations since 2008 and knew that she was cycling normally. That information combined with her history of being a good mother, made her an excellent candidate for artificial insemination (AI).

AI had never been performed on a polar bear and little information was available on the anatomy of a female’s reproductive tract or the appropriate combination of exogenous hormones that would ensure follicular development and ovulation would occur at a time favorable for insemination. In addition, there are inherent risks to anesthesia, especially with older animals. Despite these challenges, there was much to be gained by assessing the unproven male bear’s fertility, collecting the first data on hormonal induction of reproductive activity in polar bears and learning which tools and techniques are required to inseminate a female polar bear. Although AI is no substitute for natural breeding, it can be an invaluable tool for managing the gene pool and propagating species at risk of extinction that are not very prolific on their own (like captive polar bears).

Relying on information gained from other bears and large carnivores such as pandas and tigers, Dr. Erin Curry, Dr. Terri Roth and Ms. Kate MacKinnon arrived in Rochester armed with a variety of tools, equipment and back-up plans. With the help of Seneca Park veterinarians and staff, they were successful in collecting a viable sperm sample from Zero proving that he is potentially fertile. With the aid of a flexible endoscope, they were able to pass a catheter through Aurora’s cervix and into the uterus where the semen was deposited. Both bears fully recovered from anesthesia and Aurora’s most recent hormone concentrations indicate that she ovulated following the procedure, suggesting that the exogenous hormones had elicited the desired ovarian response. Since no definitive test for polar bear pregnancy exists, CREW and Seneca Park are in the wait-and-see period until late autumn when polar bears give birth to their cubs. Regardless of the ultimate outcome, this effort represents a huge step forward in advancing the knowledge and science of polar bear reproduction. (Project supported in part by a grant from the Shumaker Family Foundation and the Rowe and Elizabeth Hoffman Postdoctoral Fellowship.)

Learn More – WLWT.com story >

CREW Links Zoo with Polar Bears International as an Arctic Ambassador Center

With CREW’s expanding involvement in polar bear research, conservation and education and the Zoo’s progress in going green, it was a natural next-step to formally name the Cincinnati Zoo & Botanical Garden one of Polar Bears International’s official Arctic Ambassador Centers. PBI Arctic Ambassador Centers are organizations endorsed by leading polar bear scientists and the AZA for actively engaging in saving polar bear habitat through greenhouse gas reductions within their organizations and communities. As such, CREW and the Zoo are committed to: 1) providing information about climate change to the local community on Zoo grounds, on the website and through special programs, 2) actively reducing our own carbon emissions and 3) maintaining our polar bears in an exhibit that meets all AZA standards.

In return, we receive: 1) access to educational materials and biofacts from PBI, 2) support from PBI staff, 3) special opportunities for social networking and public relations and, perhaps most important, 4) the opportunity to engage in several unique PBI education programs.

CREW scientists are currently collaborating with 15 North American zoos to continue ground breaking polar bear research. New projects currently underway include a study of male polar bear reproductive seasonality and semen collection and cryopreservation. The establishment of a polar bear sperm bank in CREW’s CryoBioBank® will help guard against the loss of genetic diversity as this species’ numbers start to decline due to melting sea ice. CREW scientists have initiated this effort in 2010, and we now have the first cryopreserved sample of polar bear sperm in the world. However, there is still much to be learned about the best methodology for collecting and storing these samples.