Colorado Parks and Wildlife unveiled in November the results of a multi-year study on Western Slope mountain lions, showing robust population densities, while the agency’s governing body also adopted a ten-year management plan for mountain lions on the East Slope.
The density study’s results followed last month’s rejection of a ballot initiative that would have banned trophy hunting of cougars with dog teams. And the East Slope strategy largely duplicates CPW’s techniques employed on the Western Slope for the past several years.
Both the East Slope Mountain Lion Management Plan and its Western Slope cousin, finalized in 2020, will continue to allow human killing of the predatory big cats. During the most recent year for which CPW has provided data, human hunters killed 265 male cougars and 235 female cougars.
Mountain lions, also known as catamounts, cougars, or pumas, are apex predators, which mean they sit at the top of their ecosystem’s food chain. By preying on herbivores such as deer and elk, cougars prevent overgrazing and promote vegetation recovery, which in turn supports a wide range of wildlife. Research has shown that regions with healthy predator populations often exhibit greater biodiversity, as apex predators indirectly shape their ecosystems through a phenomenon known as trophic cascades.
Humans are the source of numerous threats to cougar populations, including through habitat fragmentation caused by our species’ economic activities. The growth and spread of cities, towns, suburbs, and mountain communities, including the construction of infrastructure, reduces the connectivity of their territories, which in turn makes it harder for individual pumas to find mates and maintain genetic diversity. Humans also directly kill cougars. Big cat mortality results from hunting, retaliatory killing after livestock predation, and vehicle collisions.
Compounding these challenges are the species’ biological traits. Mountain lions are solitary animals with large territorial ranges, often spanning hundreds of square miles. Females give birth to small litters, and juvenile survival rates are highly variable, meaning that populations recover slowly from declines. These factors make the species particularly vulnerable to overharvesting and habitat loss.
In Colorado, the growing human population continues to encroach on mountain lion habitat, particularly in urban-adjacent areas such as the Denver metropolitan area, Colorado Springs metroplex, and Fort Collins urban region that lie on the east side of the Rocky Mountains. Humans are more likely, as more of them live near or even in mountain lion habitat, to see the animals. And reports of encounters have increased in recent years.
Coexistence is generally peaceful – less than 30 cougar-caused human fatalities have been reported in the past century – but is not without controversy. CPW’s policies that allow and even encourage recreational hunting are often attacked by those concerned with animal welfare, wildlife protection, and ecosystem health, arguing that they undermine conservation efforts. And voices in some rural communities advocate for even more cougar killing, sometimes out of fear of the animal or concern for possible occasional livestock losses.
The West Slope Mountain Lion Management Plan, introduced in 2020, sought to consolidate smaller-scale management units into two expansive regions: the Northwest and Southwest. This approach aimed to facilitate assessment and management of populations over a larger geographic area. CPW sought to use adaptive techniques informed by modern ecological science. The density study indicates that healthy, stable populations of mountain lions may now exist on the Western Slope.
Conducted between 2021 and 2023, the Western Slope cougar density study focused on two representative areas. The first was in Middle Park, in a region between Kremmling and Granby, which recorded an average density of 2.5 independent mountain lions per 39 square miles, and the second was the Gunnison Basin, where the animal’s density was higher at 4.2 lions per 39 square miles. These results were obtained through methods that included mark-resight models and GPS collaring and surpassed earlier population projections.
“The data confirm that our measured estimates of lion density align with the population models we use for setting harvest limits,” said Mark Vieira, CPW’s Carnivore and Furbearer Program Manager. Vieira was referring to killing of cougars by people who pay CPW for the privilege of doing so.
The West Slope Mountain Lion Management Plan sets thresholds that limit adult female harvests to 22% and cap human-caused mortality at an average of 17% of the estimated population annually. These thresholds are intended as a mechanism for CPW to assure sufficient numbers of breeding female catamounts, whose reproductive rates significantly influence population dynamics.
During the Western Slope cougar density study CPW employees captured, tagged, and collared 48 mountain lions in Middle Park and 50 in the Gunnison Basin. Motion-activated cameras then recorded photos of both marked and unmarked individuals, allowing agency staff to estimate population densities using both statistical methods and field observation.
“We were satisfied to see that our measured estimates of lion density from our winter field seasons are equal to, and in some cases higher than, the lion density projections we use when making harvest management decisions,” Vieira said, according to a Nov. 12 press release.
In addition to population thresholds, the West Slope Management Plan includes a Special Management Area near Glenwood Springs. In this area CPW prioritizes reduction of human-lion conflicts; the surrounding region is one in which expanding urban development increases the likelihood of encounters. Measures include public education campaigns, targeted population control, and close monitoring of lion activity.
CPW studied cougar populations near the Book Cliffs, near Grand Junction, during the winter of 2023-2024, but has not released results of that research. The agency plans to do similar work near Durango this winter.
The newly adopted East Slope Mountain Lion Management Plan reflects a similar, decade-long roadmap for managing populations east of the Continental Divide. CPW proclaimed an objective of assuring the continued presence of cougars “for their scientific, ecological, and intrinsic value and for current and future generations to enjoy through hunting and occasional observation.”
Like its Western Slope counterpart, the East Slope cougar plan introduces landscape-scale management to replace older, localized approaches. CPW replaced six plans for managing puma in smaller geographic territories that date back 20 years. “Current scientific research . . . shows that managing mountain lions on a broader landscape is more appropriate and effective,” according to a Nov. 15 CPW press release. CPW’s emphasis on broader geographic units amounts to recognition that mountain lions often traverse large territories that are not limited to traditional, less inclusive boundaries.
CPW said that it aims to “maintain a stable lion population,” according to the East Slope cougar plan, meaning that the cougar population “will remain similar to what we see today.” The agency explained that this target eliminates previous goals in some of the smaller management territories that emphasized “harvest” of the big cats. Spreading permitted kills of cougars across the East Slope region “provides managers the flexibility to distribute” hunting caps “to meet local management needs.”
As on the Western Slope, the specific kill limits will be 22% of adult female pumas in any year, counted between April 1 and March 31, while over a three-year period the average total of human destruction of individual pumas “will not exceed 17%” of the animal’s number. CPW said it will allow, during the 2025-2026 hunting season the killing of 160 cougars, a reduction of 53 from this year. The purpose of the cutback, CPW explained, is “to allow the completion of the 10th and final year of the Upper Arkansas lion research project.”
In 2026-2027 CPW will allow 155 cougars to be killed and will not allow “total human-caused mortality” to exceed 214 lions in any year.
Mountain lions can be hunted in the East Slope Management Plan region starting the day after deer and elk season ends and through March 31. CPW said there will also be a separate mountain lion hunting season that runs from April 1-30. The plan explicitly authorizes trapping of lions with dog teams. So are “mouth-operated predator calls,” handguns, rifles, shotguns, “crossbows,” and “archery equipment.”
CPW has, practically, made clear it will not act to lessen trophy hunting of cougars after the presence of an unsuccessful measure that would have prohibited that practice on the state’s 2024 general election ballot. The proponent of that ballot initiative hinted that it may attempt it again. “The agency operates at its peril by stonewalling on obvious reforms to protect wild cats,” Sam Miller, the pro-Initiative 127 campaign manager affiliated with Cats Aren’t Trophies, said in a Nov. 6 statement. “The vote was anything but a mandate on baiting, trapping and hounding – it was a vote of deference to the agency to take action itself.”
The East Slope cougar plan also includes provisions for enhanced data collection, such as expanded use of GPS collars and motion-activated cameras, to refine population estimates and better understand lion behavior.
The CPW Commission unanimously approved the East Slope plan.
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