Wildlife of the Upper Rio Grande - Connected Corridors

Wildlife of the Upper Rio Grande

The Upper Rio Grande is home to a broad array of wildlife including bighorn sheep, elk, pronghorn, mule deer, golden eagles and Rio Grande cutthroat trout.

Canada Lynx

The Canada lynx is a threatened species that was reintroduced to Colorado twenty years ago. Logging, roads, housing developments, oil drilling and mining have disrupted lynx habitat, making it harder for the lynx to survive.

A medium-sized cat with long ear tufts and a short tail with a black tip, the lynx require a mixed habitat that includes younger forests with thick vegetation for hunting small prey and older forest with full canopy cover for denning. The Rio Grande National Forest provides core habitat for the lynx in Colorado. Lynx are solitary animals and usually hunt and travel alone at night. Their over-sized paws help them navigate across deep snow drifts in winter.

Rocky Mountain Bighorn Sheep

Rocky Mountain bighorn sheep symbolize the sheer beauty, strength and spirit of the American West. They also embody an inspiring story of recovery after near extinction. Historically, some 2 million bighorn sheep lived all across the western United States, but they began a sharp decline in the mid-1800s as a result of over-hunting, loss of habitat due to ranching and development, and the introduction of domestic sheep that carried devastating diseases. As a result, many of the herds were completely wiped out by the mid-1990s.

State and federal agencies, Native American tribes and conservation organizations began to work together to reduce disease, stimulate population growth, increase genetic diversity and limit hunting. The Rio Grande Gorge herd, which resides largely in the iconic Rio Grande del Norte National Monument, is now one of the nation’s most prolific herds and is a good example of how important cross-jurisdictional collaboration and management can be to species recovery.

To ensure a full recovery, forest planners at the Santa Fe, Carson and Rio Grande National Forests need to identify bighorn sheep as a “species of conservation concern” which will provide additional protections. The U.S. Forest Service must also develop proactive solutions to avoid conflicts and encounters between bighorn sheep and domestic sheep.

Mule Deer

Mule deer can be found throughout the Upper Rio Grande’s diverse and rich landscapes. Named for their large mule-like ears, mule deer migrate seasonally across vast distances between Colorado and New Mexico. Spending summers in the mountains and winters at lower elevations, some mule deer herds have been known to migrate more than 90 miles.

The mule deer migration paths are increasingly under threat from the expansion of roads and highways. About 4,000 mule deer are killed in vehicle collisions in Colorado every year. Fences, railroads and energy extraction also disrupt their habitat and migration trails, which is why it is so critical to protect these corridors.

Rocky Mountain Elk

Rocky Mountain elk roam widely across the Upper Rio Grande watershed, traveling extensively from high summer range in the mountains to the shrubland and deserts at lower elevations in the colder months. They are highly social animals and gather in herds for security, seeking areas away from roads and other disturbances. Elk have several protected areas to use as refuge in the Upper Rio Grande, such as the Sangre de Cristo Mountains, South San Juan wilderness areas and the Great Sand Dunes National Park in Colorado.  In New Mexico, they can be found in the Valles Caldera National Preserve, Valle Vidal, Rio Grande Del Norte National Monument and the Columbine-Hondo Wilderness Area.

Even with the abundant habitat in each of these areas, elk migrate seasonally. The pathways elk and other wildlife use are full of obstacles such as demanding topography, industrial development and roads. One major impediment is US Highway 285 through Carson National Forest, which presents a significant obstacle for elk attempting to reach critical habitat in the Rio Grande Del Norte National Monument. Understanding what elk and other key wildlife need to thrive– and then implementing management activities to meet those needs — is critical to maintaining robust elk populations in the Upper Rio Grande.

Black Bear

About 15,000 black bears live in the forests, canyons and mountains of the Upper Rio Grande. Contrary to their name, most are brown, reddish-brown or blonde. Females usually maintain a home range of 5 to 7 square miles while males typically occupy an area of 25 square miles. Those territories can be extended up to 50 square miles if habitat becomes deteriorated or fragmented.

Black bears move across the landscape seasonally in search of food and hibernate from November until early May. About 100 bears are killed from vehicle collisions in Colorado every year. Dozens of others are killed after coming into conflict with humans. The expansion of housing developments in the Upper Rio Grande area means that bears increasingly are becoming dependent on human food from trash cans that have not been properly secured. Protecting healthy habitat in undeveloped areas and reducing attractants in developed areas will help ensure robust black bear populations.


Cougars (more commonly called mountain lions) are the biggest cats found in the Upper Rio Grande region and require large land areas to hunt for food. Estimates of individual territory size vary greatly and depend on terrain, vegetation and abundance of prey. Male cougars can inhabit a territory ranging from 58 to 386 square miles; females require half that area. Cougars are solitary creatures and only interact to mate.

Because their territories are so large, cougar migration routes are frequently impacted by roads, development and other forms of habitat fragmentation. There has also been a rise in human-cougar conflicts as more people are building homes in cougar habitat. Cougars utilize many of the same migration pathways as mule deer, elk and big horn sheep, so ensuring forest-wide connectivity will help all species thrive in the Upper Rio Grande.

Rio Grande Cutthroat Trout

As the state fish of New Mexico and an iconic western species native to the Rio Grande basin, the Rio Grande cutthroat is easily recognized by its red-orange gill plates, a greenback and distinct spotting.

The cutthroat trout is a species of critical importance not only to evolution and ecology of the desert southwest, but also to the continued cultural identity and recreation of the region. As a valued native sport fish, the Rio Grande cutthroat trout is limited to a relatively small range of isolated mountain streams that have severely restricted the fish’s population. Rio Grande cutthroat trout have been replaced by non-native trout, predominately Browns and Rainbows, in 90-95% of their historic range. Pure populations now only persist in about 75 small headwater streams.

New Mexico Department of Game and Fish models show that 86% of Rio Grande cutthroat trout populations are at extreme or high risk of wildfire and catastrophic debris flows. Special management areas have been proposed in the Carson and Rio Grande National Forests to help preserve and grow cutthroat populations.


The Upper Rio Grande provides important habitat for pronghorn, who prefer vast, open terrain at elevations between 3,000 and 6,000 feet. Pronghorns are the fastest land mammals in North America and can reach speeds up to 60 miles per hour. They are also known to have the longest documented migrations in the continental United States – up to 160 miles.

While pronghorn are built for speed, they are not adept at jumping, so fences severely impact the pronghorn’s ability to move across the Upper Rio Grande landscape. One easy solution is to remove or raise the bottom strand of a fence. Pronghorn are able to pass under fences that have been raised to 18 inches or more.