SUMMIT COUNTY – A handful of Colorado Division of Wildlife teams will be fanning out across the San Juans during the next few weeks to try and count newborn lynx kittens, an endangered cat often threatened by development.
“A lot of people will be eager to see what reproduction is like this year,” said Division of Wildlife (CDOW) spokesman Joe Lewandowski. In the spring of 2006, the reproduction rate dropped significantly from the previous two years, he said, adding that researchers are curious to see if those numbers bounce back this spring.
Last year, biologists found four dens with 11 kittens. Only 10 percent of tracked females were found with litters in 2006, down from 41 percent in 2005. Between 2003 and 2006, researchers found a total of 37 dens.
Some speculated that the continued releases of new lynx in the San Juans may have disrupted existing social networks among the rare cats, listed by the state and federally as an endangered species. As a result, CDOW curtailed releases this year. The spring of 2007 marked the first time since 1999 that no new lynx were released into the wilds of Colorado.
The agency hasn’t decided if it will resume releases in 2008.
Between 1999 and 2006, the wildlife agency transplanted a total of 218 lynx from Canada and Alaska to the San Juans. As of a year ago, CDOW was actively tracking 95 of the 138 lynx that were still thought to be alive. Biologists know that 80 of those cats have died. A third of those deaths were attributed to human causes, including vehicle collisions and gunshots, while malnutrition and disease accounted for about 21 percent of the deaths.
Since all the lynx that were released are wearing transmitters, the agency is able to determine when they stop roaming and retreat to a den. Based on that information, ground crews are sent in to check the dens for kittens.
Most of the lynx have remained in the core area, from the New Mexico border north to Gunnison, west to Taylor Mesa and east to Monarch Pass. A secondary core population exists in the Collegiate Peaks/Taylor Park area. Some of the lynx have wandered as far as Montana, Idaho, Nevada, Kansas and South Dakota.
Some of those cats were recaptured and re-released in the San Juans, Lewandowski said.
Mature Engelmann spruce and subalpine fir forest stands were the areas most frequently used by lynx in southwest Colorado.
No lynx dens have yet been located on the White River National Forest or in Summit County. But the local area is an important north-south crossroads and a crucial link if the cats are to spread back into their historic range across all of Colorado’s mountains. So far, 43 lynx have been located in the White River National Forest, according to a CDOW report issued last year.
“Lynx use the entire area between Bakerville (east of the Eisenhower Tunnel) to Vail Pass to go from the southern part of the state to the north,” said CDOW’s Rick Kahn, coordinator the lynx program.
The increasing number of lynx using the White River National Forest doesn’t surprise White River forest biologist Keith Gietzentanner.
“The majority of the forest is pretty good lynx habitat,” Gietzentanner said in a previous interview, explaining that the rugged mountains of the forest have plenty of the terrain favored by the cats – steep, high altitude north-facing slopes with plenty of downed timber for cover and forest patches of varied ages, where there is food and habitat for snowshoe hares, a mainstay of the lynx diet.
Gietzentanner said some lynx may even be setting up territories on or near the White River, especially south and east of Aspen and south of Vail in a triangular area roughly bounded by Vail, Tennessee Pass and Copper Mountain. That patch of forested mountains was described by Gietzentanner and other federal biologists as a “secondary core area” and “study area” for lynx, outside the immediate release zone in the San Juans, where many of the transplanted cats have settled.
Bob Berwyn can be reached at (970) 331-5996, or at firstname.lastname@example.org.