For captive polar bears, mating is often a public encounter. Such is the case for the pair at the Alaska Zoo in Anchorage.
Zookeepers have been watching what they call "breeding behavior" between 15-year-old female Ahpun and 13-year-old male Lyutyik, known as "Louie," and they have seen a lot more activity this spring than in years past. The bears have been together since 2006 -- the ultimate goal of that pairing is companionship and, maybe, producing cubs -- but it was not until the last two years that the bears have been seen copulating regularly.
With concerns that wild polar bear populations are in decline, successful breeding among any polar bears is more important than ever, species experts say.
Despite the lingering challenge of Ahpun's implanted birth control lasting longer than planned, the hopes of the zoo's staff are higher than ever that Ahpun and Louie will reproduce. And as the Alaska Zoo prepares to expand its polar bear exhibit to include a maternity den, they are waiting, watching and writing down what they see.
"Whenever anybody sees them breeding, it goes out on the radio," said Pat Lampi, the zoo's director. "So much of the time, they really do get along together and sleep next to each other and play together. But this time of year, they're extra close to each other."
That means lying down side by side, grooming each other and curling up together, Lampi said. On a recent spring day, the bears could be seen facing each other, sprawled on the ground in their enclosure, touching paws.
The first report this year of actual mating was March 31, when Joel Holyoak, outreach coordinator in the Alaska Zoo's Education Department, was taking a group of third-grade students on a behind-the-scenes tour. There were a couple chuckles from the kids, he said.
"I told the students we were all really lucky to see what was going on," Holyoak said. "I just told them that they were breeding and attempting to have babies, not really getting into big details. Yeah, it was a little weird, but really more exciting."
Getting 650-pound Ahpun and 1,200-pound Louie together was a herculean effort, but well worth it, Lampi said. For Ahpun, from the Alaska Arctic, it was not nearly as difficult as Louie, who came from Australia.
Lampi had been working at the zoo for over a decade when Ahpun arrived. In 1998, a hunter near Point Lay shot Ahpun's mother, thinking the bear was a male because no cub was nearby.
Subsistence hunters are generally allowed to hunt polar bears, but it is illegal to knowingly kill a female with a cub.
"But they were responsible enough to see that she was lactating, follow her tracks back, go down in the den, and rescue the cub," Lampi said.
The Alaska Zoo's polar bear enclosure had been empty since their previous pair, Nuka and Binky, had died. Instead of sending Ahpun to another zoo, it was clear that the Alaska Zoo would be able keep her, Lampi said.
"I spent a lot of time with her when she first arrived," Lampi said. "For me, it was one of the funnest times I've ever had here at the zoo."
Lampi stayed with Ahpun through her first night, he said. He put on Carhartt coveralls. "Even that little, they can bite pretty hard."
The then-16-pound bear huffed at him upon exiting her crate, swatted at him a couple times and bit his boots, Lampi said. Within a half-hour, though, Ahpun was sleeping on his legs, he said.
"I think it was probably just the body heat. I wasn't threatening to her, I was just talking to her, and I just had some warm legs to come curl up on," Lampi said. "I'll have to say she's a favorite, because she's one of the first bears I got to keep and raise here. I'll always tell people, 'She's the best looking bear you'll ever see at the zoo."
"She's just a beautifully stunning, very white looking polar bear."
A few months after Ahpun's arrival, the zookeepers introduced a brown bear cub, Oreo, so the bruins could keep each other company. Years later, though, Oreo became aggressive toward Ahpun and they had to be separated, Lampi said.
That left Ahpun lonely. Then came word that the Sea World in Queensland, Australia (not affiliated with the SeaWorld Theme Parks in the United States) was looking for a new home for one of its male polar bears.
"They wanted to start breeding polar bears, so they brought in some nonrelated males, and they had to move Louie out," Lampi said.
Louie, originally from a zoo in St. Petersburg, Russia, had been living with his sister and was comfortable being around another polar bear, Lampi said.
He was about to head back north.
Lampi started the piles of paperwork that Louie's Australian keepers wanted: resumes of Alaska Zoo staff, schematics of the polar bear exhibit, medical records of past polar bears at the zoo, among other things.
"It was very, very thorough," Lampi said. "As well it should be."
The Alaska Zoo and Sea World of Australia split the roughly $20,000 shipping cost to get Louie to Alaska. It was August 2006 when he was put in a crate, trucked to Brisbane, and flown on Qantas Airlines to Sydney, Shanghai and on to Anchorage, Lampi said. The trip took 28 hours, with keepers feeding Louie through chutes and removing his urine and feces from trays on the bottom of the crate, Lampi said.
When Louie finally met Ahpun, he wanted to be near her right away, Lampi said.
"Her last experience had been with Oreo, the female brown bear who was a bit of a bully, so she was not too sure," Lampi said. "At first there was a lot of posturing and loud vocalization. But it took only four days until we saw the behaviors that we were looking for. Calmly lying close to each other with a grated door between them, playing footsie."
The bears have copulated since then, but only in the last two years have there been multiple sightings in the same year. The zoo keepers have been testing for hormones in Ahpun's feces for signs that she might be pregnant, and once a year the bears are sedated in order to perform a blood draw to do more checks, Lampi said.
"She was looking pretty big last year," Lampi said, and there was suspicion that Ahpun might be pregnant. But tests confirmed she was not, he said.
Ahpun's persistent birth control is likely preventing that, Lampi said. She was last given the Deslorelin in June of 2010 -- it looks like a piece of chalk and is implanted in the bear's shoulder -- and had been getting the drug, like with any birth control, to prevent a previously unwanted pregnancy, he said.
"After a period of time, after a couple years, it's supposed to disperse and they're good to go again," Lampi said. "But it's taking much longer, and it's unknown how long it's going to take for them to conceive."
It's a problem other zoos with hopeful polar bear breeding programs are seeing, said Randi Meyerson, a curator of mammals at the Toledo Zoo, in Ohio, and coordinator of the polar bear species survival plan for the American Zoo and Aquarium Association. The Toledo Zoo has been successful in breeding polar bears and had two females give birth in 2006, Meyerson said.
In the 1990s, zoos were less interested in allowing their polar bears to breed, because the animals' plight in the wild was either less known or less severe at the time, Meyerson said. The birth control made it possible for zoos to keep their male and female bears together. If the females were in heat, but held in another part of the enclosure, it was hard on the males, Meyerson said.
"We tried to use this short-term contraceptive, which was medically safe for them, so that we could keep the bears together and they wouldn't be stressed by being close but not together," Meyerson said. "Unfortunately, in polar bears, in over five years, it has not been reversible."
There is some concern that the effect is permanent, Meyerson said, but biologists have seen similar issues in big cats on the same drug. The birth control took longer than expected to wear off for them, too, but the cats were eventually able to conceive, she said.
Ahpun is in her prime age for having a cub, Meyerson said, and the longer the birth control lasts, the more concern there is that time may be running out. Lampi said successful breeding tapers off when female polar bears reach their mid- to late-20s.
Keeping a healthy population of polar bears in captivity helps the struggling wild bears -- hurt by Arctic sea ice melting thought to be due to climate change -- in a variety of ways, Meyerson said.
Research projects that would be difficult, dangerous and expensive to complete in the bears' natural environment are much easier with trained bears in a zoo, Meyerson said. That includes testing of the bears' hearing to see if natural resource development, on the North Slope for example, can be heard by a female polar bear in a den, Meyerson said. If the noise is disruptive, the research can help inform developers on how far away to build things like ice roads, she said.
Knowledge gained by caring for polar bears at the Alaska Zoo has helped in the zoo's effort to prepare for the potential of an oil spill on the North Slope, said Lampi, who designed a cleaning table for an "oiled" bear that can hold 2,000 pounds.
Plus, the charismatic polar bears have a role as ambassadors for many threatened Arctic species to help biologists and others explain to people the impact of global warming, Meyerson said.
"We cannot save polar bears as a species without ice," she said. "If the only way to save ice is to get people to change their habits and decrease their carbon footprints, well zoos, we're the best place to do that."
Breeding polar bears in captivity in a way that keeps their genes diverse, and avoiding the concentration of negative traits that inbreeding causes allows zoo keepers to continue that public outreach and research. It also keeps a healthy "insurance population," Meyerson said.
That's not to say that if wild polar bears become extinct, it would be possible to breed and release captive bears. A bear raised in captivity would not know how to hunt, Meyerson said. However, if zookeepers were able to collect semen from a captive male polar bear and inseminate a female in the wild, it might be a way to help save the species by keeping them genetically strong, she said.
"We're sort of not closing the door on anything right now," Meyerson said.
At the Alaska Zoo on Friday, Louie and Ahpun rested on opposite ends of the polar bear exhibit. Every so often, Louie raised his snout and sniffed the air in Ahpun's direction. Neither seemed interested in mating.
"I think the breeding behavior might be over now," Lampi said.
It's a season that's hard to predict, Lampi said. Female polar bears can go in and out of estrus multiples times in a spring, he said.
And while the zoo could care for a cub now, Lampi said, it would be easier with a maternity den, which would allow Ahpun to hole up and give birth with more privacy.
The zoo expects to break ground on a long-planned expansion of its polar bear exhibit this summer and continues to accept donations. The two-phase, $8 million project will start with Phase 1 by building a dedicated area to care for orphaned polar bears, mostly out of the public's sight. The design includes den space for as many as a half-dozen cubs and the maternity den for Ahpun or any other female polar bears the zoo may house in the future.
When it's time to go into that maternity den, a pregnant female will give telltale signs, but usually not until the fall, said Meyerson, of the Toledo Zoo.
There is a delayed implantation of the fetus in its uterus, and the bear will begin to eat and drink less, typically in mid- to late-October, Meyerson said. In Toledo, the zoo staff remove the animal from its exhibit and give it access to a den, "to start quieting life down," Meyerson said. Birth happens within a couple months, she said.
It is not a true hibernation as with other species of bear, Meyerson said. The mother bear will wake up and care for the cubs during that time, she said.
During the Toledo Zoo's past polar bear pregnancies and successful births, zoo staff watched the process via video cameras.
"It was pretty amazing," Meyerson said.
At the Alaska Zoo, a polar bear cub is still just a dream in the making. If Ahpun does not turn out to be pregnant in the fall, which is still possible, it will be at least another year.
"I'd love to see her have a baby," Lampi said. "It's part of nature. It's the completion of a life cycle. She's such a beautiful bear. She should be passing on her genes."
By CASEY GROVE