Colorado’s lynx reintroduction project — centered in the San Juan Mountains — has accomplished its goal of establishing a breeding population in the Southern Rockies, state officials announced Friday.
Colorado Division of Wildlife Director Tom Remington said that biologists are now transitioning to monitor the cats’ long-term persistence in Colorado’s high country.
The announcement comes following the discovery this spring of 14 lynx kittens in five separate dens, including the first two dens documented in Summit County, outside the core reintroduction area. As only some breeding-age female lynx are equipped with satellite collars, the 14 kits represent the minimum number of lynx births this year.
Between 2003 and 2010, researchers documented that at least 141 lynx kittens were born in Colorado. Analysis of observational data indicates that the cats’ reproductive rate has outpaced mortality in the 11 years since the reintroduction program was launched, which is the hallmark of a self-sustaining population. DOW biologists believe lessons learned from this program could be helpful in developing a plan to reintroduce wolverine to Colorado.
Gov. Bill Ritter hailed the success of the reintroduction project.
“Protecting and enhancing Colorado’s wildlife heritage takes hard work and dedication,” Ritter said. “I commend the Division of Wildlife for this accomplishment. It's an example of what we can do when we have a vision and the will to see it through.”
Remington said the lynx project is one of the most ambitious and significant state-led reintroductions in recent years.
“The Division of Wildlife has a long tradition of restoring and recovering native species in Colorado,” Remington said. “This is a tradition that ranks among the division’s finest achievements. I applaud the wildlife professionals whose commitment and expertise have made the lynx project a success. Today is a proud day for the agency.”
The DOW began reintroducing lynx in 1999, releasing lynx captured in Alaska and Canada into the San Juan Mountains.
From 1999 to 2006, the DOW introduced a total of 218 lynx, monitoring radio- and satellite-collared lynx as they colonized the core area and expanded their range into other parts of Colorado’s high country. The mid-sized lynx has proved adept at adjusting to Colorado’s rugged mountains, finding both food and habitat necessary for successful reproduction in at least six of the past eight years.
Lynx reproductive rates have varied greatly since kittens were first documented in 2003. After den visits identified 16 kittens in 2003, researchers found 39 kittens in 2004; 50 kittens in 2005; 11 kittens in 2006; 11 kittens in 2009; 14 kittens in 2010.
During the 2006, 2009 and 2010 seasons, DOW field crews documented that Colorado-born lynx had successfully produced third-generation Colorado kittens. In 2010, researchers estimated that between 30 and 40 percent of female lynx bore litters of kittens.
DOW biologists suggest the lack of documented reproduction in 2007 and 2008 and the variability in the number of kittens produced by collared females year-to-year is consistent with what researchers know of lynx populations in their traditional strongholds in the northern boreal forest.
There, lynx populations track the cyclical abundance of snowshoe hares, the primary winter food source for lynx. Numerous studies in Alaska and Canada document that lynx reproductive success oscillates with snowshoe hare numbers. DOW researchers say 2007 and 2008 represented low years in snowshoe hare abundance in Colorado.
Biologists also documented the Colorado lynx population’s ability to successfully target their traditional secondary food source, red squirrels, in times of snowshoe hare scarcity. In 2009, scat analysis suggested squirrels made up 66 percent of lynx diets.
“What we’ve seen from lynx in Colorado is exactly what we’d expect to see from lynx in their northern habitat,” said retired DOW biologist Tanya Shenk, the lead researcher on Colorado’s lynx project from 1999 to 2010. “This supports our strong belief that the habitat in Colorado will sustain lynx over the long term.”
However, biologists caution that climate change, events such as wildfires and bark beetle epidemics along with future development could alter key portions of potential lynx habitat in Colorado in unforeseen ways.
To track the lynx population, biologists will now pursue a site occupancy monitoring strategy, using minimally invasive techniques like trail cameras, snow-tracking and genetic sampling to monitor the presence or absence of lynx in established and potential habitats. This will replace the strategy of capturing and collaring individual lynx to gain detailed knowledge of their movements, habits and fate.
The new approach will give biologists a better understanding of the lynx population throughout Colorado, although yielding less data on individual cats.
“This is a more cost-effective strategy that avoids subjecting individual cats to the stress of capture,” said Scott Wait, DOW Southwest Region senior biologist. “But it will give us a better way to track the persistence and hopefully expansion of lynx populations.”
“We’ve done everything necessary to restore lynx to Colorado,” added Rick Kahn, the retired DOW terrestrial resources manager who spearheaded the reintroduction program for over a decade. “Now it’s up to the cats to continue to respond as they have for the past 10 years.”
Colorado launched its reintroduction program despite the possibility that lynx would be added to the federal Endangered Species List. In 2000, the lynx was listed as threatened under the ESA due to their inadequacy of existing regulatory mechanisms to protect the species and its habitat in the contiguous United States. DOW officials will continue to work with the Fish and Wildlife Service to define federal benchmarks for the continued recovery in Colorado — such as the creation of a Recovery Team and a Recovery Plan for lynx in Colorado and nationwide.
The Colorado Lynx Reintroduction Program required the support of numerous personnel in the DOW, other state and federal agencies, the Colorado General Assembly, the administrations of three different governors and the general public. Such sustained dedication has resulted in the successful reintroduction of this species to Colorado’s
Funding for the reintroduction program was provided by Great Outdoors Colorado, Vail Associates, the Colorado Wildlife Heritage Foundation, the Turner Endangered Species Foundation, the U.S.D.A. Forest Service, private donations and the DOW.