Biologists anxious to learn whether lynx are reproducing

Biologists anxious to learn whether lynx are reproducing

August 30, 2001

By Gail Binkly
Journal Managing Editor

Biologists are waiting with a mixture of optimism and anxiety to see whether any of the Canada lynx reintroduced to Colorado have reproduced.

"We’re still tracking approximately 60 lynx," said Jim Olterman, the Division of Wildlife’s senior terrestrial-wildlife biologist for western Colorado. "They’re making it OK. What we need now is some babies."

The lynx, a bobcat-like predator that dwells in snowy, high-elevation forests, was declared a federally threatened species under the Endangered Species Act on March 21, 2000. Although common in Canada and Alaska, lynx have been declining for decades in the Lower 48 states.

The last lynx documented in Colorado was in 1973 near Vail — until February 1999, when the DOW began releasing lynx into the southern San Juan Mountains. A total of 96 of the radio-collared cats, all trapped in Canada or Alaska, were turned loose near Creede during the early months of 1999 and 2000.

According to the DOW’s lynx web site, last updated on July 8 of this year, 37 of the lynx are known to have died, leaving 59 possibly still alive.

Of the mortalities for which the cause was known, the greatest number — nine — were caused by starvation, with another five animals being killed by vehicles and five being shot.

The mortality rate has been substantially lower than in most predator reintroductions, which typically have a mortality rate of 50 percent or higher, researchers say.

"It’s lower than we expected it to be when we first conceived the project," Olterman said.

More deaths occurred among animals released during the first year than the second. The mortality rate was especially high for the first few lynx set free, which soon starved.

Biologists then changed their protocol and began fattening the animals up for a longer period before releasing them and turning them loose in the spring rather than in mid-winter.

The surviving lynx are subsisting largely on snowshoe hares, along with some red squirrels and cottontail rabbits, according to the web site. Many have cached part of their kills, indicating they have more than enough to eat.

But, with no more lynx reintroductions planned, the success of the effort now depends on whether the animals will raise young that can survive on their own.

"They’ve demonstrated they can find food and there’s plenty to eat," Olterman said. "The question is whether we’ve got enough density for the males and females to get together in March for breeding season and for the young to survive."

Most of the lynx remain in a core area bounded by the New Mexico state line on the south, Gunnison on the north, Taylor Mesa on the west and Monarch Pass on the east — though some have strayed into Utah and one roamed cleared to Nebraska.

Olterman said researchers believe some of the animals may have been able to mate this year.

"It’s hard to tell (through radio tracking) if they’re right together," he said. "But there’s been a number that have been in close proximity, and there’s been some females that have not moved very much. We think maybe they’ve got a den when they do that, but we just don’t know."

Researchers are reluctant to try tracking the females on the ground for fear of disturbing them if they have kittens, he said.

"We’re real nervous about bothering them too much. Up north, it’s been demonstrated that if you bug them for about an hour, they may abandon those young ones, and that’s the last thing we want to happen."

When winter comes, however, trackers will look in the snow for the furry-footed animals’ characteristically large tracks — and any smaller tracks following the females.

"I think the crews are going to go out after the first snowfall and locate the animals with the radios and intercept their tracks," he said. "Some time in September we’ll get a snow and then they’ll go out and check.

"It’s really important this year that they reproduce. We didn’t really expect any kittens last year because we hadn’t released many lynx at that point. But now we’re hoping to see some little ones."