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RBC | Colorado’s “mule deer factory” may be in trouble, and Colorado Parks and Wildlife (CPW) has come up with a plan to try and save it by reducing predator numbers.
The Piceance Basin supports the largest migratory mule deer population in Colorado for winter range. This area has been monitored and researched since the late 1940s for management of the mule deer population.
In the early 1990s, the mule deer population declined by about a third of the previous winter range density, prompting the reduction of total mule deer licenses in the area by 85 percent for antlered deer and 99 percent for antlerless deer. Current license allocation consists of 590 antlered deer and 20 antlerless deer licenses.
In 2008, CPW initiated research to determine the effect of energy development in the Basin on the mule deer population. Data shows that December fawn weights have increased, winter fawn survival has more than doubled and winter starvation has become rare. However, December fawn counts have declined from about 73 fawns/100 does to 49 fawns/100 does.
Recent investigation into newborn fawn survival suggests predation is the largest factor in fawn mortality, with at least 50 percent of collared fawns succumbing to predators, mostly mountain lions and black bears. By reducing the number of predators in the area, CPW hopes to allow the mule deer population to return to higher levels.
“Our deer population around the state is down,” said Bill deVergie, Wildlife District Manager in Meeker. In response, CPW drafted the Mule Deer Strategy in 2014, creating a plan for protecting and rebuilding the herd that includes predation management.
Because the Piceance Basin area has been well-monitored for predation, it provides the “perfect opportunity to do the predator component,” deVergie said. “We have a baseline out there, so we can do some of the manipulations. The control numbers are already done here.”
In May and June of 2017, CPW will begin euthanizing 5-10 mountain lions and 10-20 black bears in a specific area of the Piceance Basin. The proposed reductions are consistent with the current mountain lion management objective of maintaining relatively low predator densities for reducing livestock conflicts. The plan will be considered effective if fawn predation rates from black bears and mountain lions is reduced from 50 to 30 percent, and there is a subsequent increase of at least 15 percent in fawn survival.
Increasing the number of hunting licenses for mountain lion and bear would not serve to solve the fawn predation problem, deVergie explained. “The seasons are outside of the scope,” he said. Bear and mountain lion seasons take place in the fall and winter, while deer generally give birth in mid-summer.
deVergie also said that while motor vehicles play a role in mule deer deaths, he believes the numbers from predation, particularly of fawns, is higher.
This research project will begin spring 2017 and continue through December 2019. Annual expenses will average $210,247 with $157,685 (75 percent) expected to come from federal aid (PittmanRobertson) grants and $52,562 (25 percent) from CPW matching funds (Wildlife Cash).