He's strong, healthy and hirsute. She's social and friendly, with Rubenesque curves. Yet the dalliances of this walrus couple have failed to yield a baby, a fact that confounds experts at Vallejo, Calif.-based Six Flags Discovery Kingdom, which seeks to breed the rare and mysterious species. So scientists are making the first-ever attempt at artificial insemination -- if only they can persuade male Sivuqaq, a rambunctious creature the size of a Volkswagen, to donate sperm.
"Once we get the sperm, we're good to go," said marine mammal reproductive physiologist Holley Muraco. "I feel confident that we're going to have walrus babies."
The love lives of Pacific Walruses are shrouded in secrecy. They mate underwater, at remote, vast and icy habitats, during the Arctic Circle's longest and darkest nights. And there is growing concern for their survival because sea ice is melting. Zoos don't want to collect from these perilous wild populations, and seek instead to increase the genetic diversity of their captive populations.
In the eight decades that walruses have been kept captive, only 11 babies have been born; of those, merely six survived. Fewer than 20 now exist in American zoos, and many are aging, Muraco said.
Hopes are pinned on Sivuqaq and Siku, or perhaps another female, Uquq -- among America's youngest and healthiest captive walruses. Orphaned when their mothers were killed during an Eskimo hunt, they were recovered off the coast of Gamble, Alaska.
So far, they've been star-crossed, their cycles sadly out of sync. Siku and Uquq produce eggs just once a year -- in the spring. But Sivuqaq is most romantic in the winter.
"The females ovulate like champs," Muraco said. "But there's nothing to give them. His good stuff happens later."
So scientists are working to align the reproductive cycles, artificially. They've identified what stirs Sivuqaq's passion: Strollers. Running children. A recycling bin. Power tools.
"He loves it when workmen are doing something loud with hammers and drills," Muraco said. "It is almost a territorial thing. He'll puff up and make groans, whistles and a low growl."
He's been taught to roll over and expose himself and he obliges on a simple cue: "Penis!" It is a daunting 30-pound, 3-foot-long organ. Walruses have the largest organs in the mammalian world.
Finding a super-sized artificial vagina has proved a bigger challenge. Six Flags bought the largest one on the market, specifically designed for huge draft horses, but even that proved too small. So scientists have decided to custom-build one out of PVC pipe. Their final task will be building a mount that's sturdy enough to support Sivuqaq's 2,900 pounds, yet fuzzy enough to put him in the mood.
Already, Muraco has collected vast amounts of data that reveal the daily, weekly and monthly shifts in the walruses' hormones such as testosterone, progesterone and estradiol. Every day, the animals open their giant mouths to provide a saliva sample, swabbed with Q-tips. Once a week, they offer up a flipper to donate blood.
"They trust us," she said. "They've been here since they are 3 months old. There's a bond."
Videotape analyses help scientists link the animals' behavior to hormonal changes.
"Sivuqaq is a mellow, hanging-out, eating, sleeping guy when his testosterone levels are low," Muraco said. "When it's rising, he shows rutting behavior, growing larger and posturing to people, growling."
The fertility cycles of Siku and Uquq are also tracked like clockwork. With an Army-issued ultrasound -- portable, battery-operated and water-resistant -- Muraco scans their organs for signs of increased blood flow, which signals a developing follicle that leads to ovulation. As Muraco massages the animal's vast abdomen, Siku relaxes, her eyelids drooping.
Artificial insemination has already succeeded in creating baby sea lions, harbor seals, dolphins and killer whales. In these animals, the problem isn't successful mating. The more challenging task for scientists in artificial insemination is picking the healthiest parents, creating a strong and genetically diverse generation of youngsters.
"We better figure out something soon," she said. "We can learn from these trained animals, and use it to help endangered species and put the research out there for others. We owe it to the world."