The effects of the sedative were wearing off Vladimir, a five-year-old Western gray wolf living at the Wildlife Science Center, so Peggy Callahan knew she had to work fast.

The center, just outside Forest Lake in Columbus, has for years worked to ensure future survival of red and gray wolves by freezing and storing their sperm. For most people, the collecting of wolf sperm is a source of disgust, but for scientists it's genetic gold.

It will be stored in vials at a sperm bank in Missouri, to help replenish the wolf population, if their numbers go south again.

On this morning, Callahan reached for a thin plastic catheter from a table covered with an assortment of semen-collecting tools: an electro-ejaculator machine, pipettes, and stacks of clear party cups. "We come into town and people think we're going to have a great big party," said Dr. Cheryl Asa, a visiting reproductive physiologist. Callahan stroked Vlad's fur.

The gray wolf population, which collapsed in the 1970s after decades of being hunted, trapped and poisoned by ranchers in the Southwest, has rebounded significantly. In December, the U.S. Fish and Wildlife Service proposed to have it taken off the endangered species list.

At the wildlife center, a 7-acre nonprofit conservation site where about 100 wolves and other predators — among them, mountain lions, lynxes and coyotes — roam, researchers have for years studied the effects of a so-called genetic bottleneck caused by inbreeding. The center, which Callahan founded in 1994 with some of her own money, has tackled other genetic puzzles. Among them, fine-tuning a nonsurgical insemination technique and developing nonlethal ways to keep wolves away from livestock.

Their most recent project involves developing procedures for "freezing and thawing" wolf semen, Asa said, snapping on a pair of latex gloves.

Callahan walked over to Asa, the director of research at the St. Louis Zoo who lectures on animal behavior at Washington University in that city. Asa is part of a team of researchers from the Endangered Wolf Center in Eureka, Mo., who gather in Minnesota every February during breeding season. The team huddled over Vlad.

They drained the wolf's bladder into an empty Diet Coke bottle. The rest watched as Callahan fired up the electro-ejaculator, which was developed by "a man working with parapalegics coming back from the Vietnam War who wanted to store their semen," Asa said. The wolf's leg jerked with each electric shock.

They collected five or six party cups of semen, none of them full. For years, Callahan said, the procedure was done manually.

A few feet away, standing by a gas fireplace, Pam Larson quietly pointed out something to her 14-year-old daughter, Judy, who has considered a career working with animals and hopes to volunteer at the center.

"To have something this close is a great opportunity," said Pam Larson, who made the hourlong drive from Cologne, Minn. "I went to school in Iowa; these opportunities aren't close by."

An amateur photographer, she watched with interest.

Back in the fenced-in area, Callahan's husband and fellow researcher Mark Beckel was trying to coax the pack's alpha male, Chief, into a holding pen. After climbing into an adjoining cage with another wolf, he called out in a high-pitched nasal voice to Chief, who ignored his advances.

"Chief!" "Chief!" "Chiefer!"

Still, nothing.

"Come on, Mark. Turn it on. Turn the charm on. It works with us," quipped another researcher.

Beckel sighed, and turned back to the enclosure.