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Lynx reintroduction program hindered by lack of hare research

Bob Berwyn
Summit County Correspondent
Vail, CO Colorado

Lynx reintroduction program hindered by lack of hare research

Biologists say more research is needed on key prey species

By Bob Berwyn

summit daily news

Summit County, CO Colorado

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A lynx is released into the wild near Creede in 2001 as part of the state’s ambitious reintroduction program.

A lynx is released into the wild near Creede in 2001 as part of the state’s ambitious reintroduction program.ENLARGE

A lynx is released into the wild near Creede in 2001 as part of the state’s ambitious reintroduction program.

Summit Daily file photo

This lynx, released near Creede, was treed by dogs near Cheyenne, Wyo., demonstrating that the cats can range long distances in search of food and habitat.

This lynx, released near Creede, was treed by dogs near Cheyenne, Wyo., demonstrating that the cats can range long distances in search of food and habitat.ENLARGE

This lynx, released near Creede, was treed by dogs near Cheyenne, Wyo., demonstrating that the cats can range long distances in search of food and habitat.

COLORADO ” Colorado’s $3.5 million lynx-reintroduction effort was started before basic research was undertaken on the availability of its main prey, snowshoe hares, scientists now acknowledge after no new kittens were found for the second straight year.

“Nobody did the hard work before the introduction to see of there’s enough prey,” said Kevin McKelvey, a Montana-based biologist who has recently studied snowshoe hare ecology in Wyoming. “There has always been the question: Are there enough snowshoe hares?”

Just before the federal government listed lynx as threatened under the Endangered Species Act, the Colorado Division of Wildlife launched an ambitious program to bring the cats back to the state.

Between 1999 and 2006, more than 200 lynx were trapped in Alaska and Canada and released in the San Juan Mountains.

In the last two years, however, reproduction plummeted to zero, prompting biologists to speculate that snowshoe hare populations might be dipping to a normal, cyclical low.

But at this point, nobody knows for sure because of the dearth of research on hares in Colorado.

“It would have been so helpful to have some hare population data up front,” said Clayton Apps, a Canadian researcher who studied lynx in British Columbia for several years.

A close relationship

So closely interlaced is the predator-prey relationship, it’s impossible to understand lynx population dynamics without looking at snowshoe hare populations, which peak every eight- to 11-years, said Leonard Ruggiero, a Montana-based Forest Service researcher.

“We don’t have any place where we have lynx but no snowshoe hares,” Ruggiero said. “The relationship is lockstep.”

Although the cycle is well understood in the northern reaches of Canada, more research is needed in Colorado to determine to what degree hare populations fluctuate and whether there are enough to sustain a healthy population of lynx, he said.

Without an adequate supply of snowshoe hares, their diet might be just short of the level needed to sustain reproduction. The females might even be conceiving embryos but re-absorbing them into their bodies for lack of that final nutritious meal.

State wildlife officials concede that they don’t fully understand the local dynamics of lynx and snowshoe hares, but they remain confident that the reintroduced population of cats is viable.

“We’ve always known it’s an experimental population,” said Joe Lewandowski, spokesman for the Colorado Division of Wildlife. “Ten years ago when it started, anecdotally people saw plenty of snowshoe hares. People were saying, ‘There are lots of snowshoe hares. Well, gee, why study them?'”

Before the lynx program started, there was some speculation that hare populations in Colorado do fluctuate but not at same dramatic amplitude as in more northerly boreal forests.

Wildlife officials contend that the overall population of lynx remains healthy.

The agency has identified 116 kittens that have been born in Colorado, and adults have survived for years and maintained good condition, according to biologists.

Scientists have tracked the cats closely via satellite positioning systems and recorded successful breeding, especially in 2005 and 2007.

The adult lynx being tracked by state biologists are healthy and well-fed, so they are finding some prey. The cats are also showing mating behavior, according to the tracking data.

Political decisions?

Looking back, it might have been a good idea to do some basic snowshoe hare population studies before launching the lynx program.

But the political will and available funding ” as well as the desire to avoid federal regulations associated with the Endangered Species Act ” spurred the state into action.

A high mortality rate from starvation among the first batch of transplanted lynx may have been a sign that the program was rushed at the outset, however.

Just in the past couple of years, the Colorado Division of Wildlife has started some small-scale hare studies.

In Canada, where biologists already understand the cyclical nature of the local hare and lynx populations, they simply count hare pellets left in marked plots of land.

But Tanya Schenk, the lead biologist for Colorado’s lynx program, explained that there can be a significant margin of error in pellet-count studies.

“It’s not as easy and straightforward as it sounds,” she said.

Rather than relying on pellet counts, the state studies involve counting the hares themselves, she said.

Getting a handle on whether there is a natural cycle, and how far apart the highs and lows are, means collecting data over the course of at least one or two cycles, or eight to 22 years.

The U.S. Forest Service is also doing some pellet counts on the Routt National Forest and Schenk hopes some of the study results will start to show a clear picture of hare populations.

“Monitoring snowshoe hare populations would be the way to manage for lynx. But it’s an issue of resources and priorities,” Schenk said.


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