Mammals & Birds
A ptarmigan in winter plumage.
The Lake Fork watershed boast abundant wildlife!
Herds of Elk and mule deer roam the forests and alpine in the summer and descend to sagebrush habitat in the winter. The surrounding region boasts some of the best populations of Rocky Mountain big horn sheep in the state, although we only have two distinct populations in our watershed. The pika, a small rabbit sized mammal, lives in the alpine year round. Black bear are relatively common, as are mountain lions, coyotes and bobcats. Recently introduced species include Canada lynx and moose.
More than 200 species of birds are present in the summer months, including ospreys, golden eagles, white-tailed ptarmigan, Gunnison sage grouse, boreal owls, and many migratory neotropical species.
Many streams and gulches provide rich habitat for hundreds of species of aquatic insect and fish, which draws a number of anglers. Most of the fish species are non-native except for one species, the Colorado River cutthroat. The cutthroat once lived in the lower Lake Fork, but now only exist in a few high lakes and short reaches of streams. Rainbow trout, brown trout and brook trout have displaced the native species and are thriving in the clean, productive streams of the watershed. Exotic Mackinaw trout have now seriously altered fish species composition of Lake San Cristobal.
The Uncompahgre Fritillary
Discovered only in 1978 and described as a new species in 1984, Boloria acrocnema is endemic to the high alpine meadows of the San Juan Mountains in southwestern Colorado. Intensive collecting pressure, improper grazing by domestic livestock, periods of prolonged drought conditions, mining activity, and an increase in alpine recreation coincided with a dramatic population decline and led to its listing as an endangered species under the U.S. Endangered Species Act in 1982.
The Uncompahgre fritillary butterfly lives in patches of snow willow (Salix spp.) at high elevations frequently above 12,000 feet. Its very limited habitat, small population size, and low genetic variability may affect long-term population stability. The species is susceptible to trampling by recreationists and grazing animals.
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