A new Colorado Parks and Wildlife report highlights the wide-ranging threats being posed to crucial big-game migration corridors and winter habitat, from construction of new homes and increased recreation, to highway collisions and energy development.

The report was conducted in response to an executive order issued last August by Gov. Jared Polis, who directed CPW and the Colorado Department of Transportation to work cooperatively to improve conservation of big-game winter range and migration corridors. The report is intended to guide those agencies and other partners in that work, and lay the groundwork for eventual policy, regulatory and legislative recommendations.

The Polis initiative followed the issuance of an order in 2018 by Ryan Zinke, then secretary of the Interior Department, aimed at improving habitat quality in western big-game winter range and migration corridors.

According to the CPW report, Colorado has taken advantage of grant funding resulting from Zinke’s order in several ways. It has obtained hundreds of thousands of dollars for purposes such as placing global positioning system collars on animals to help researchers study migration and habitat issues, and for installation of wildlife fencing.

This week, Interior Secretary David Bernhardt announced more than $4.4 million in grants for migration corridor and winter-range projects in western states, including $3.1 million from a public-private partnership with the National Fish and Wildlife Foundation. These grants included $480,400 to go toward a Colorado Department of Transportation wildlife underpass project north of Craig on Colorado Highway 13, which also includes the installation of fencing to guide wildlife to the underpass.

According to the new CPW report, many major roadways in the state are in low-lying river valleys and canyons important to winter range and migration corridors. It says winter range quality and quantity are one of the primary limiting factors for big game populations.

The report says nearly 4,000 wildlife-vehicle collisions are reported each year by law enforcement, but most reported incidents involve big game that cause damage and research suggests collisions involving wildlife may be underreported by up to 80% or more.

“Based on CPW’s mule deer intensive monitoring studies, 2% of collared doe mule deer are killed by vehicle collisions annually. This is more than the amount of doe deer harvested by hunters each year,” the report says.

It noted that a study analyzing data from 1980-2010 in western Colorado found that by 2010, an average of 31% of mule deer winter ranges were affected by residential development.

It points to energy-development impacts that go beyond those from fossil-fuel projects such as oil and gas drilling, and also result from renewable projects, such as fenced solar arrays that can cause a complete loss of habitat for big game. It also highlights habitat impacts caused by factors from invasive species to climate change.

The report notes that CPW, through its Wildlife Habitat Program, has invested about $152 million securing conservation easements on 250,000 acres. It also works with partners on winter-range habitat restoration projects, but such work needs to increase in pace and scale, the report says.

CPW is working on research projects such as addressing elk response to human recreation in order to establish mitigation and planning options, and exploring the use of habitat treatments to deal with energy development impacts.

It also is planning short-term work in the next few years such as collaborating with CDOT to standardize recording of wildlife collisions, and defining and identifying big-game transitional range. The report outlined longer-term needs that could inform its habitat management decisions, such as identifying bottleneck areas for big-game movements, and determining the impacts of train collisions on herds. But it currently lacks the staff or resources to meet those needs now, according to the report.

The report may be found at https://cpw.state.co.us/Documents/Hunting/BigGame/2020BigGameWinterRangeandMigrationCorridorsReport.pdf.

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