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The Biological Community
The San Miguel valley's east-west orientation differs markedly
from other valleys in southwestern Colorado, which generally
run north-south. The resulting differences in insolation have
allowed several plant communities and habitats to develop on
the valley floor which are potentially unique in the region.
These include narrowleaf cottonwood and blue spruce riparian
woodlands as well as willow/carex marshes, which are known to
support some of the richest songbird communities in Colorado.
Invertebrates are abundant in the river's headwaters and on the
valley floor, indicating good river health and constituting a
critical link in downstream food-chains. Although the river has
never been a great fishery, due to steep gradients, lack of structure,
and periods of inadequate water flow, it does house several species
of trout as well as smaller, non-game fish.
The San Miguel basin is also home to a number of important game
and non-game vertebrates, including several species either listed
under the Endangered Species Act or which are candidates for
listing. Black bear, elk and mountain lions are relatively common
in the area, and are increasing in number. Bighorn sheep occupy
the hills above Telluride, and numerous small mammals, songbirds,
raptors, reptiles, amphibians, and fish make use of the riparian
zones along the river. Several species of particular concern,
including Gunnison's sage grouse, river otters, Colorado River
cutthroat trout, and bighorn sheep occur within the watershed.
Recently, a Canada Lynx, reintroduced to Colorado as part of
an experimental recovery population, has also frequented the
area.
Like many regions of North America,
the San Miguel valley's invertebrate communities have been relatively
little studied until recently. During the 1940's and 50's, the
author and butterfly systematist Vladimir Nabokov frequented
the valley, describing a new Lycaenid or blue butterfly from
areas near Telluride. The endangered Uncompaghre fritillary (Clossiana improba
acrocnema) is restricted to mountainous areas nearby. As well as butterflies
and moths, the region supports a diverse
community of other insects and arachnids. Despite their previous
lack of attention, these creatures play critical roles in maintainging
ecosystem functions, and inventorying the area's invertebrate
biodiversity is an important conservation goal.