Colorado Parks and Wildlife estimates that the state is home to between 3,800 and 4,400 mountain lions, but officials have been working to get a better grasp on the elusive cat population numbers and density as part of the agency’s 2020 management plan for the Western Slope. 

On Nov. 12, Parks and Wildlife released the first results of the yearslong data collection, sharing what it found in Middle Park (between Kremmling and Granby) and in the Gunnison Basin. 

“These results show that the lion populations in these representative study areas are strong,” Mark Vieira, the agency’s carnivore and furbearer program manager, said in a news release.

The studies of Middle Park and the Gunnison Basin, which began in 2020 and 2021, were aimed at understanding how many independent mountain lions, both juvenile and adult, live in different habitat types and areas of the Western Slope. To determine this, Parks and Wildlife staff and researchers captured, marked and collared lions, monitoring them with cameras, as well. Trained hounds were used to track and capture the cats. 

Ultimately, the agency was able to collar or mark 48 lions in Middle Park and just over 50 in the Gunnison Basin. These collars will automatically drop off the animals after three winters of study.  

During the 2021-22 and 2022-23 winters, results indicate there were an average of 2.5 independent lions per 60 square miles in Middle Park. In the Gunnison study area, there were an average of 4.2 independent lions per 60 square miles. 

Vieira emphasized that this data indicates higher lion numbers compared to studies of lions in other states and is higher than the projections Parks and Wildlife has been using to make management decisions.

In addition to studying population density, Parks and Wildlife staff also collected blood and other biological data from the captured lions. 

Parks and Wildlife is conducting similar research in the Book Cliffs north of Grand Junction and will start a fourth study east of Durango this winter. Research on mountain lions on the Western Slope will continue over the next 10 years. 

These areas were selected because they are representative of quality lion habitat and see a range of hunting pressure on lions. 

In its lion management plan for the Western Slope, Parks and Wildlife suggests that these numbers will help it refine and improve the assumptions it makes about the state’s lion populations. These numbers are used to help the agency set annual hunting limits. 

From west to east

While this research was part of Parks and Wildlife’s West Slope Mountain Lion Management Plan, it passed the final version of its complementary plan for the eastern half of Colorado on Nov. 15. 

These two plans represent a shift in management strategy for the agency around lions. Previously, the cats were managed by 19 area plans. However, consolidating these into two plans better represents how the carnivores move around the landscape. 

While both plans continue the practice of hunting mountain lions as the primary management tool for sustaining the carnivore’s population, they also set two new, independent thresholds that could impact the number of hunting licenses issued each hunting season. 

This includes a limit on the number of female lions hunted each year — setting it at 22% of the population, below the previous annual average of 40%. It also places a cap on human-caused mortality — which are lion deaths outside of hunting, including vehicle collisions and livestock conflicts — at 17% of the population over a three-year average. Either threshold, independently triggered, would cause a reduction in the number of hunting licenses issued. 

Both of these thresholds are dependent on reliable population estimates. 

The East Slope Mountain Lion Management Plan would initiate similar density studies of mountain lion populations in the eastern half of the state, like the west slope plan did in 2020. The initial areas identified for these studies include the canyons, mesas and plateaus south of U.S. Highway 50 and east of Interstate 25 in southeastern Colorado as well as a region in the Greenhorns-Spanish Peaks region. 

The plans also identified other future research needs for the carnivores, including the public perception of lion management in Colorado, whether the hunting of adult male lions disrupts social order and leads to more conflict, the potential impacts of human development on habitat and more.