New Heights

In 2nd grade, we learned about biomes. A biome is a region of the world dominated and defined by a specific type of vegetation and possessing a unique climate. Major biomes of the world include tropical rainforests, deserts, coniferous (cone-bearing) and deciduous (broad-leaved) forests, and the arctic tundra. I remember writing a paper on musk oxen on the tundra. My idea of the tundra back then was of a frozen wasteland at the top of the world, kind of like the images of Santa’s workshop sitting amidst drifts of unyielding snow. But did you know that Colorado also has a tundra habitat and that it’s surprisingly full of life?

Summit Lake on Mount Evans. Photo by Jamie Simo.
Summit Lake on Mount Evans. Photo by Jamie Simo.

Colorado’s tundra is of the alpine rather than the arctic variety. This means that, rather than being at the top of the world, Colorado’s tundra “biome” exists on the tops of high mountain areas. Alpine tundra exists as a function of elevation. As elevation increases, temperature decreases. Climbing 1000 feet is roughly equivalent to traveling north 600 miles. In general, increasing elevation also means increasing precipitation.

The western half of Colorado is also generally wetter than the eastern half. This is because, as wet air travels east across the Rockies, it rises and its temperature drops. Cold air is less able to hold moisture than warm air and so it condenses and falls back to the ground as precipitation on the western slope and on the mountain peaks. This phenomenon, called a “rain shadow,” is why the eastern plains are so dry.

I say that higher elevations are generally wetter than lower ones because that’s not true for the alpine tundra where strong winds and a lack of trees contribute to drive most moisture (in the form of snow) off the mountain tops and into lower areas. It’s a self-perpetuating cycle:  Trees can’t grow with so little moisture and without them, there’s nothing to hold the moisture (snow). As a result, the treeless tundra is dominated by rocks and tiny grasses and herbs.

Queen's crown. Summit Lake trail on Mount Evans. Photo by Jamie Simo.
Queen’s crown. Summit Lake trail on Mount Evans. Photo by Jamie Simo.

While most of the year the alpine tundra is a bitterly cold, frozen place, its brief summer boasts some of the most spectacular wildflowers I have ever seen. Every color of the rainbow from the pinks and reds of queen’s and king’s crown to the blue of chiming bells, to the yellows of old man of the mountain dot the rocky landscape. This display attracts a surprisingly number of animals taking advantage of the bounty while they can. These include big-horned sheep, mountain goats, pika, and yellow-bellied marmots.

A short-tailed weasel (also known as an ermine) with its deer mouse prey at Summit Lake on Mount Evans. Photo by Jamie Simo.
A short-tailed weasel (also known as an ermine) with its deer mouse prey at Summit Lake on Mount Evans. Photo by Jamie Simo.

Some birds are alpine specialists, like the brown-capped rosy finch, which gleans insects attracted to the pink patches of blue-green algae growing on the surface of unmelted snow. Of course, the white-tailed ptarmigan is a year-round resident of the tundra, changing color to blend in alternately with the exposed rocks and the snow.

Because of its remoteness and harsh climate, the alpine tundra is one of the most pristine habitats within Colorado and there are several great places to experience it before winter closes in again. The road to Mount Evans recently reopened and the trail around Summit Lake is a beautiful hike that also offers one of the easiest access points to a Fourteener in the state. The drive along Trail Ridge Road in Rocky Mountain National Park is also a great way to visit the alpine tundra. Neither road will be open that much longer this year though so I urge you to go visit them now unless you want to wait until next summer.

Summer Tenants

One of the cool things about Colorado is that, with so many diverse ecosystems, you never know what you might see. Prairie dogs are a familiar sight along the Front Range, but only about 2% of historic black-tailed prairie dog habitat remains. Loss of habitat has been due to human encroachment via farming, ranching, and subdivision-building. This means there is less habitat for animals that depend on prairie dogs for their livelihood, like these burrowing owls (Athene cunicularia), which I’ve been seeing lately at Coyote Ridge open space near Fort Collins.

Burrowing owl at Coyote Ridge Open Space in Fort Collins. Photo by Jamie Simo.
Burrowing owl at Coyote Ridge Open Space in Fort Collins. Photo by Jamie Simo.

Burrowing owls arrive in Colorado in March or April to breed and nest and they may lay as many as a dozen eggs, though few of those chicks survive to adulthood. Because burrowing owls are active during the day as well as at night, they’re relatively easy to see if you can find the right place. However, burrowing owls are a State-threatened species here in Colorado, so it could be tricky to find where they’re nesting. The owls depend on prairie dogs because they take over unused prairie dog burrows so threats to prairie dog colonies are also threats to burrowing owls.

A coyote at the eponymous Coyote Ridge Open Space near Fort Collins, CO. Photo by Jamie Simo.
A coyote at the eponymous Coyote Ridge Open Space near Fort Collins, CO. Photo by Jamie Simo.

Burrowing owls are a small (only about 10 inches tall), spotty brown bird with long legs and big yellow eyes framed by white eyebrows that can make them look a little angry. Their long legs allows them to perch atop prairie dog mounds or on taller vegetation to see over the short grasses they prefer to make their homes amidst. Their long legs also allow them to run in addition to flying in order to escape predators, such as coyotes, hawks and eagles, or, in more urbanized areas, domestic cats and dogs, or to find prey.

A burrowing owl takes flight at Coyote Ridge Open Space. Photo by Jamie Simo.
A burrowing owl takes flight at Coyote Ridge Open Space. Photo by Jamie Simo.

Burrowing owls eat a whole host of things from mammals like small rodents, to birds, to reptiles and insects. This time of year grasshoppers are plentiful, so no doubt they’re a staple of their summer diet. Around mid-October, birds in the northern reaches of their range, including Colorado, migrate to the southern U.S., Mexico, or Central America. Other birds where temperatures are more consistent, such as southern portions of Texas, New Mexico, and Arizona, are year-round residents. Amazingly, burrowing owls are not only present in the western U.S., but also in Florida, and areas in South America. It’s a surprisingly wide-spread species, which may be why it’s not listed as Federally endangered despite declines in its population.

A good time to see burrowing owls is in the early morning or evening. At Coyote Ridge, you can easily see them with binoculars, though a spotting scope can be helpful to make out more details. Check them out! They probably won’t be around too much longer; fall is creeping up on us and winter will be close behind.

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