Wisconsin Rapids Daily Tribune

Sun, Jan 4, 2004

Studies show elk calves less vulnerable to bear predation

By Jim Lee

Gannett Wisconsin Newspapers

Calves born in Wisconsin's maturing Clam Lake elk herd appear less vulnerable to predation from black bears and timber wolves than initially suspected.

"We could find no evidence that any elk calves were killed" by predators during the 2002 and 2003 calving period, said Laine Stowell, a Department of Natural Resources elk research biologist.

Stowell is working with Tim Ginnett, a University of Wisconsin-Stevens Point professor of wildlife management, and UWSP graduate student Melanie Hansen on a study of predator impacts on the state's fledgling elk herd, using data collected from radio-collared bears, wolves and elk.

Chris Thomas, assistant dean of the UWSP College of Natural Resources and a member of the Natural Resources Board, also is involved in the project.

In 1995, the DNR released 25 elk from Michigan into a selected region of the Chequamegon National Forest that included portions of Sawyer, Ashland, Bayfield and Price counties. The herd currently numbers about 120 animals.

Prior to 2002, there were indications that bears were targeting elk along with deer fawns during the late May and early June birthing season, Stowell said.

"We were seeing about one-quarter of the elk calves taken (by bear) in 2001 and earlier years," Stowell said, "but our sample size was small."

What happened to change the predation picture?

The sex and age makeup of the herd changed significantly, Stowell said, and that altered the calf birthing date.

"Prior to 2001, we had relatively few bulls available to do the breeding .. about three or four bulls," he said. "Each bull had a large harem of 10 or 12 cows. He didn't have to work to get a harem together, and there was little competition.

"During the last two ruts, that changed. In 2002, there were 12 bulls putting together harems of three to five cows. There was more bugling and there was more competition for the cows.

"Research has found that bugling helps synchronize a cow's estrus. The result is a much more efficient elk rut, which corresponds to a shorter rut and an earlier calving season." The latter circumstance appears to be the major factor in reducing bear predation on newborn elk calves.

Bear are more numerous than wolves in the Clam Lake area. The population has been estimated at 1.1 bears per square mile of bear range. "That's a lot of bear," Stowell remarked.

Before spring 2002, elk calves were born about June 1. Whitetail deer fawns in the same area traditionally begin appearing about May 26 and 27. Studies by biologist Orrin Rongstad earlier had documented that 19 to 24 percent of the deer fawns born in northwestern Wisconsin were killed by black bears.

The suspicion is that bears have become attuned over time to anticipate the deer fawning period as an opportune moment to obtain much-needed nutrition after a long winter hibernation, Stowell said.

When elk calves were born during or after the deer fawning period, they became a natural target for bears.

In 2003, when spring was slow to arrive, elk calves began appearing May 24. In 2002, the calving date was May 20, nearly a week before most deer fawns began appearing.

"I think it's a situation where bear have learned that at a certain time of year, when the woods smell a certain way, that there's a food source of fawns out there," Stowell said.

By giving birth prior to the deer fawning period, elk calves avoid becoming most vulnerable at a time when bear are focusing on deer fawns, he said.

An elk calf, similar to a deer fawn, depends on remaining motionless to avoid detection by predators during the days immediately after birth.

"We have not had problems catching calves up to 7 days old," Stowell said. "An 8-day-old fawn can outrun us, but it might not be able to outrun a bear. By the time a calf is 10 to 14 days old, it moves with the cow to a nursery group of females and calves. There's usually six to 12 animals in a group. That's a lot of ears and eyes ... so a calf is usually safe from most predators once it reaches that stage."

Timber wolves, though steadily expanding throughout the state, have not yet begun to target elk. They probably find it easier to bring down deer, which are smaller and more numerous in the area, Stowell said.

The elk killed in 2003 was the first in four years attributed to wolves. Previously, three yearling elk were killed by wolves in 1999.

Predation appears to be less of a factor as the elk herd matures, Stowell said. http:///