Zoo officials hoping for a polar bear cub
Artificially inseminated Anoki may be pregnant, but no one can tell
The Maryland Zoo’s polar bear Anoki may be pregnant, but no one knows for sure.
She’s hiding in her den and may give birth to a furry white bundle of joy later this fall.
Or maybe not.
The prospect that Anoki might ever get pregnant seemed hopeless when her mate died two years ago.
But
After weeks of giving Anoki hormones to prepare for the procedure, doctors used an endoscope and catheter to deposit the sperm during a 45-minute procedure last February. The sperm came from a bear named Hudson who lives at the Brookfield Zoo in Chicago.
Now zookeepers and scientists from Baltimore and Cincinnati are awaiting anxiously to see if the procedure worked, Anoki is pregnant and the old bear has a cub. “This is something that we are very excited about,” said Dr. Ellen Bronson, director of animal health, conservation and research at The Maryland Zoo. “We would be thrilled if we had a cub come out of this.”
If Anoki is able to conceive and deliver a cub, the scientists hope the procedure could become a tool to prevent further declines in the polar bear population. In 2008, polar bears were listed as threatened under the Endangered Species Act as melting polar ice reduced the habitat of what are the largest land-based carnivores in the world. There are about 26,000 polar bears still living, according to the International Union for Conservation of Nature.
No one knows if Anoki is pregnant even though the artificial insemination took place months ago. It takes months between the time polar bears breed and when the female becomes pregnant because of a phenomena called delayed implantation.
Polar bears in the wild breed in the spring, but the tiny embryo floats around until it implants in the uterus in the summer. Polar bears need perfect conditions to become pregnant. A female polar bear is able to use the time to assess whether she is ready for pregnancy.
“They do all their breeding in the spring,” said Erin Cantwell, mammal collection and conservation manager at The Maryland Zoo. “Then they spend all summer eating and trying to put that weight on and get their bodies ready for pregnancy. Late summer or fall is when the implantation would really happen.”
The female polar bear then digs a den to wait out her pregnancy. Anoki went into an artificial den earlier this week. Staff are checking and watching her via video and regularly monitoring her hormone levels. She will not be seen by visitors to the zoo for several weeks as the staff tries to keep her in an undisturbed environment.
They won’t know if the insemination worked until she delivers a cub. There is no pregnancy test for polar bears.
The embryo also could absorb back into the body rather than implant in the uterus in a so-called pseudopregnancy. And polar bears show the same symptoms, including high levels of the hormone progesterone, when they are pregnant as they do if the embryo is absorbed into the body.
So the zoo staffs wait. They know the chances of a pregnancy are slim, but they are hopeful.
Most polar bears have their cubs in November or December — Thanksgiving is a particularly common time. Mom and offspring stay in the den for several months after the cub’s arrival.
Anoki is the fifth polar bear that the Cincinnati Zoo scientists, who are studying fertility issues in polar bears, have tried to impregnate through artificial insemination since 2012. They started studying them and later trying to breed them after they were put on the endangered species list.
The scientists started by using the fecal matter of female polar bears to test hormone levels to see if they were ovulating regularly. The test showed they were and the scientists turned to artificial insemination, which has been performed successfully in tigers, elephants and rhinos, but not polar bears. “We were really starting from scratch,” said Erin Curry, a reproductive physiologist with the conservation center at the Cincinnati Zoo & Botanical Garden.
The polar bears that have been artificially inseminated include one at Seneca Park Zoo in Rochester, N.Y., and another at Sea World in San Diego. Not all the zoos publicly announced that they tried the procedure, Curry said. Zookeepers in Rochester were concerned that their male polar bear was infertile because he could not get his female mate pregnant. She had gotten pregnant after coupling with another polar bear in the past.
“She ultimately didn’t have cubs,” Curry said. “Hormonally, she looked good. So we don’t know if it was a lost pregnancy or a true psuedo pregnancy, which means there was not a pregnancy at all.”
An official with Polar Bears International in Montana said that zoos have been more active in the research of polar bears for roughly the last decade. Researchers looking at captive bears can capture things that would be impossible in the wild, said Geoff York, senior director of conservation for the group. For instance, cameras can be placed in the dens of captive polar bears that may be able to see if there are differences in behaviors between those who have cubs and those who don’t.
“We have no idea what’s going on in there,” York said about the dens. “We don’t know exactly when cubs are born and what happens when they are born and when they emerge.”
York said he hopes the research provides more insight on the fertility of polar bears. “The research that Cincinnati and Maryland are doing is just going to help us better understand polar bear reproduction,” he said.
Even if Anoki does not deliver a cub, the scientists said it still was important to try to impregnate her. They hope to learn more about the ideal conditions for a polar bear pregnancy and, in the long run, help boost the polar bear population. And they believe that one day, the procedure will work. The researchers in Cincinnati also are working to develop a pregnancy test for polar bears, Curry said.
“If we don’t get a cub out of this, it was super important for us to participate and help along the science,” Cantwell said.
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