Razorback Sucker—Like other native Colorado River fish, the razorback sucker declined as a result of damming and water diversions that lowered water temperatures, blocked migration to spawning grounds and flooded or dried out habitat. Razorback suckers inhabit the muddy backwaters and tributaries of the Colorado River. Wonderfully adapted to life in the murky depths, suckers use their lips to pluck worms and invertebrates from the bottom, helping recycle nutrients from sediments. Once widespread in the Colorado River system, razor-back suckers are now found only in small numbers in the Yampa, Colorado and Gunnison rivers.
Wolverine—The scientific name for this large member of the weasel family, Gulo gulo, translates as "gluttonous glutton." Wolverines have a broad diet including live prey and berries, but they seem to prefer carrion. It's likely that wolverines were never common in Colorado, because we are on the southern edge of wolverine range. However, many of those in the state were killed when they ate poisoned baits and carcasses set out for coyotes. Wolverines are known for their ferocious temperament. They will drive other predators, even bears and mountain lions, from a kill. Wolverines inhabit dense mountain forests. Colorado has the habitat, but it's uncertain whether any still live in our state.
Least Tern—This smallest of North American terns has long, tapering wings and a forked tail. Channelization and irrigation practices in Colorado destroyed the river sandbars and sandy shore areas originally inhabited by these graceful birds. And because terns nest on sandy beaches, recreational use of their nesting grounds further disrupted their breeding success. Although terns nests are frequently flooded out by fluctuating water levels on irrigation reservoirs, that is where least terns are found in Colorado today.
Piping Plover—Populations of these little shore-birds with the piping call, cousins of the killdeer, have declined in Colorado because of habitat alteration and destruction of nesting sites. Similar to the least tern, piping plover habitat has been altered with channelization and modification of seasonal river flow. Diversion of peak flow (which would have scoured river sand bars and made sandy nesting areas available to the plovers) allows encroachment of vegetation and destruction of nesting sites. Plovers now nest on the sandy beaches of irrigation reservoirs that are exposed when water levels are low. Unfortunately, in high water years the birds may return to previous nesting grounds to find their habitat unavailable.
Next: Colorado Success Stories
(The information contained in this issue of Colorado's Wildlife Company was accurate at the time of original publication. Situations and circumstances described, staff positions, contact information, and dates of some events may have changed in the interim. Present knowledge and understanding of biological and behavioral facts and information may also be different than presented here.)