Colorado Front Range

A Landscape of Remarkable Diversity

What is the Colorado Front Range? 

The term Colorado Front Range is a general term; it has no specific legal definition or boundary. It generally describes that area where the spine of the Rocky Mountains reach their most eastern point and the alpine, subalpine, montane, foothills, and high plains immediately to the east.

For this website, the front range is defined as the area bounded by Interstate 25 on the east, the Continental Divide on the west, the Wyoming-Colorado border on the north, and the southern border of  Pueblo county. This region encompasses Larimer, Boulder, most of Broomfield, Gilpin, Clear Creek, Jefferson, western Denver, western Douglas, Park, Teller, western El Paso, Fremont, and western Pueblo counties.

 Life Zones of the Colorado Front Range 

As you travel from the plains into the mountains, the landscape changes dramatically. Temperature, precipitation, and vegetation change with elevation, creating different life zones—areas with their own characteristic plants and wildlife. These changes are important to butterflies because caterpillars depend on particular host plants for food. As the vegetation changes from the plains to the alpine, so do the butterflies that live there.

Within this broad region are five major biological life zones—plains, foothills, montane, subalpine, and alpine. This remarkable range of elevations (approximately 5,000 feet (1,500 meters) up to over 14,270 feet (4,350 meters), diverse habitats, and plant communities provides an equally remarkable variety of places for butterflies to live. The Front Range is home to a rich diversity of butterflies. Boulder County alone has verified records of more than 200 species, while approximately 226 species have been reported across the broader Front Range, based on records in Butterflies and Moths of North America.

The Colorado Front Range includes five major life zones:

Plains / Grassland (3,500–5,500 feet)

The plains are generally warm, dry, and open, with grasslands, prairie plants, and agricultural areas. Common plants include blue grama grass and prickly pear cactus. Butterflies you may see: Viceroy, Black Swallowtail, and Checkered White.

Foothills (5,500–8,000 feet)

The foothills are a transition between the plains and mountains. Rocky slopes, open areas, and forests of scrub oak, mountain mahogany, piñon pine, and ponderosa pine provide a variety of butterfly habitats. Butterflies you may see: Colorado Hairstreak, Anise Swallowtail, and Hoary Elfin.

Montane (8,000–10,000 feet)

Cooler and wetter conditions support forests of ponderosa pine, lodgepole pine, Douglas fir, and aspen. Open meadows, streams, and forest clearings provide habitat for many butterflies. Butterflies you may see: Western Tiger Swallowtail, Weidemeyer's Admiral, and Green Comma.

Subalpine (10,000–11,500 feet)

Long, cold winters and short summers create a shorter growing season. Spruce and fir forests surround open mountain meadows where hardy plants and butterflies thrive. Butterflies you may see: Ruddy Copper, Mormon Fritillary, and Common Alpine.

Alpine / Tundra (Above 11,500 feet)

Above the tree line, conditions are cold, windy, and challenging. Trees cannot grow here. Instead, low-growing wildflowers, sedges, and lichens cover the ground. Butterflies you may see: Rocky Mountain Parnassian, Mead's Sulphur, and Grizzled Skipper.

Riparian / (Found across all altitudes)

Areas of unique vegetation and wildlife adjacent to streams and rivers. Wetlands, willow, and cottonwood trees along river and stream corridors.

Join us in celebrating the butterflies of Colorado’s Front Range.