As I was putting together an earlier blog on bighorn sheep in Colorado, I started to wonder about the actual distribution of the Rocky Mountain bighorn sheep (Ovis canadensis) compared to the desert bighorns (Ovis canadensis nelsoni) in the parts of Colorado I've explored. For example, the bighorn sheep found in Bighorn Sheep Canyon near Canon City,
Colorado, have smaller, lighter horns and a generally smaller body size than those I've seen near Colorado Springs. This can be observed in the comparison photos above and below. Since I want to make sure I'm identifying them correctly in my keywording and other wildlife notes, I reached out to Forest Service rangers in several districts, as well as to the Rocky Mountain Bighorn Society for additional information. Additionally, I researched several online articles for insight into the ranges and distribution of bighorn sheep. Here's a quick synopsis of my research.
In Colorado, Rocky Mountain bighorn sheep are found the length of the Front Range from north of Fort Collins south to Trinidad. Very few herds are found east of the Rockies, but there is a mapped range along the Purgatoire River east and north of Trinidad, which makes sense because of the rugged, steep canyons the river follows. Overall, Rocky Mountain bighorns range throughout the Rockies in Colorado to just west of Gypsum, Aspen, Gunnison, and Monte Vista. Although their populations were severely depleted in the late 1800's to early 1900's in Colorado, they're now generally considered to be safe, although they continue to need conservation monitoring because individual populations can be at risk.
Habitat fragmentation with resulting genetic limitations to smaller, and more isolated, herds is possibly the most common concern. Bighorn sheep can also be infected by diseases found in domestic cattle and sheep; competition for food in areas where there are cattle and sheep can also affect the health of bighorn herds.
We saw this ewe and her lamb next to the highway along Blue Mesa Reservoir in the Curecanti Recreation Area just west of Gunnison last summer. According to an email from a Forest Service ranger in answer to my question, Blue Mesa Reservoir is the furthest west that Rocky Mountain bighorn sheep are found along Highway 50. In their natural habitat, they're wonderfully camouflaged; indeed a dozen vehicles sped by with their occupants looking at us (obviously wondering what we were looking at), and never saw these animals nor the herd they were with.
Regarding desert bighorns (Ovis canadensis nelsoni), although they were once native to Colorado, they became extinct in the state at some point. During the late 1970's, desert bighorns were introduced back into Colorado near the Colorado National Monument west of Grand Junction and Fruita. According to an email I received from Terry Meyers, Executive Director at the Rocky Mountain Bighorn Society, "The only desert sheep herds in Colorado are along the lower Colorado River between Grand Junction and the Utah state line, along the Gunnison River between Delta and Grand Junction, and the Dolores River from below McPhee Reservoir to Paradox Valley."
This part of Colorado contains a portion of the Colorado Plateau, a huge geological area encompassing many of the west's most beautiful national parks, monuments, national historic parks and sites, and some of the most rugged geology found in the United States. The Plateau stretches generally from southwestern to northeastern Utah, down the far western side of Colorado, northwestern to north-central New Mexico and northern Arizona, covering the entire Four Corners region. Desert bighorn sheep range throughout this enormous territory, but are still considered to be extremely endangered in Colorado. According to information I located on Wikipedia, in 2018 there were only 4 desert bighorn hunt units in the state, showing a total population of around 500 animals.
Much of the reason I love photography is the fact that I can return home and research the plants, animals and locations I've photographed. I've learned so many wonderful natural history facts and bits of scientific trivia in the course of researching my images. I hope you'll explore my website further to see what I've gleaned based on the descriptions of some of the images posted.
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