Threatened and Endangered Wildlife

Natural Resources & Environment>Threatened &Endangered Wildlife

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There are a number of wild species in Colorado that are either endangered or threatened. An endangered species is one that is in such danger that it could become extinct. A threatened species is a species that is in risk of becoming endangered. It is very important that everyone realizes what wildlife species are already endangered and are threatened, so we all can help protect the diverse wildlife Colorado has to offer.

Bald Eagles
Lynx
Boreal Toads
River Otters
Wolverines
Grizzly Bears
Gray Wolves
Kit Fox
Black-footed Ferrets
Whooping Cranes
Peregrine Falcons
Colorado Native Fish

Bald Eagles

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Description: The bald eagle(Haliaeetus leucocephalus), named because of its white head, is found only in North America, and it's the continent's second largest bird of prey. Only the California condor, also on the federally endangered list, is larger.Here in the United States, the bald eagle is recognized as the country's national symbol, a distinction it has held since 1872. Young bald eagles are dark brown in color when they fledge the nest at about 12 weeks of age. Their head and tail feathers turn predominantly white in the fourth or fifth year. Adult males weigh about eight to nine pounds. Females are slightly larger, about 10 to 14 pounds. The birds' length is 31 to 37 inches with a wingspan of 6 to 7.5 feet.
Range: Historically, bald eagles lived throughout North America from Alaska to Newfoundland, and from Florida to California. But numbers started to decline in the last century due to nest damage caused by pesticides, human disturbance and loss of trees for nesting habitat. Since the bald eagle was placed on the Endangered Species List and the pesticide, DDT, was banned, bald eagle populations have rebounded.
Habitat: Bald eagles are seldom seen far from water, such as large rivers, lakes, and seacoasts. In Colorado they are often found near reservoirs, especially where there are abundant fish. In 2001, there were about 51 nesting pairs of bald eagles in the state. Two decades ago, bald eagles were extremely rare in Colorado and throughout the Continental United States.
Diet: In addition to fish (self-caught or stolen from other birds), bald eagles eat sick and injured waterfowl, muskrats, squirrels, rabbits, prairie dogs, and often carrion and road-killed animals.
Reproduction: Nests can be seven to eight feet across, usually in tall trees high above the ground. Bald eagles often choose dead limbs in tall trees, possibly because their view is not obstructed by foliage. Nests are often found near water. Female lays one to three eggs, which are dull white. The incubation period is about 35 days, with both the male and female keeping the eggs warm.
Endangered status: The bald eagle is on the U.S. Endangered Species List. It is classified as threatened in all of the continental United States, except Alaska. Eagle abundance declined nationally due to increased human impacts in primary nesting areas. These impacts included habitat destruction, illegal shooting, and pesticide poisoning. Historically, only two to three pairs of bald eagles nested in Colorado, but the nesting pairs have recently increased by eight or nine each year. In 2001, there were an estimated 51 breeding pairs in the state. Colorado is a very popular wintering area for bald eagles. The annual midwinter count shows a stable population of up to 800 eagles. The San Luis Valley in the southern part of the state is one of their favorite places because of its supply of fish and waterfowl from open water as well as its population of rodents and rabbits.

Courtesy of CDOW [Click here to view full size picture]

Lynx

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Description: Lynx are about the same size as a medium-sized dog, weighing from 18-44 pounds. They are 31-51 inches long, with a very short tail of two to nine inches. Lynx have large feet and long legs. They may appear to be stooping over, but that is because their hind legs are slightly longer than their front legs. Their fur is gray to reddish-brown with muted, or barely visible, spots. A ruff of hair surrounds their face and long, dark hairs form tufts at the tips of their ears.The life span for a lynx is up to 15 years.

Range/Habitat:Lynx prefer living in coniferous forests. A coniferous forest is one primarily of cone-bearing trees, like pines, spruces, firs, and larches. Lynx like forests with many different sized trees and a thick understory. Understory is the vegetation or plant-life on the forest floor. This type of habitat is also ideal for their preferred prey species, the snowshoe hare. Yet, lynx are very adaptable and can live in rocky areas, open areas, scrub bush, and even dunes. Lynx rest or bed under ledges, trees or in caves. In bad weather they may bed under thick spruce trees.

Local Distribution: Lynx can be found from New Mexico north to Gunnison, west as far as Taylor Mesa and east to Monarch Pass. There are some lynx north of Gunnison up to the I70 corridor and in the Taylor Park area. No lynx are known to be north of I70 at this time.

Diet: Lynx prey mostly on snowshoe hare. Scientists estimate that snowshoe hares make up about 80% of their diet. However, when hares are scarce they will prey on grouse, ptarmigan, pine squirrels, marmots, mice, ground squirrels, beaver, muskrat, and other small animals and birds. Lynx occasionally eat deer, elk, and even moose when they can kill a calf or fawn. They also scavenge and will eat carrion. Carrion is meat from animals that died of other cause, like old age, disease, accidents, or other predators.

Reproduction:Kits are what we call baby lynx. After a 9-week gestation period, female lynx or "she cats" give birth to litters of kits in May or June. Between one and four kits are born in each litter. Kits are born with fur. However, kits are helpless when first born, because they are born blind and their eyes are closed. In March or April, when lynx kits are about 10 months old, they leave their mother's care. Lynx may or may not mate. If prey is abundant, then nearly every lynx will mate, but if prey animals are in short supply, lynx may not breed at all. In average years, lynx will mate their second winter.

Status: The lynx is considered a threatened species, but as of now the species is secure.

Boreal Toads

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Description: The boreal toad is Colorado's only alpine species of toad. Females generally grow to 11 centimeters and males to 9 centimeters. Both sexes appear warty and usually have a light stripe along the middle of the back. Juveniles may have red warts.
Range: The species occurs throughout most of western North America, from southeastern Alaska to northern Baja California, Utah and northern New Mexico. In Colorado, the boreal toad is restricted to the southern part of the Rocky Mountains and is found at elevations between 7,000 and 12,000 feet.
Habitat: Distribution of the boreal toad is restricted to areas with suitable breeding habitat in spruce-fir forests and alpine meadows. Breeding habitat includes lakes, marshes, ponds, and bogs with sunny exposures and quiet, shallow water.
Diet: Boreal toads feed on a wide range of invertabrates and insects, including flies, mosquitoes, grasshoppers, beetles, and moths.
Reproduction: Toads breed in still waters in marshy areas from May to late July. Unlike many species of toad, the boreal does not have a loud mating call. Males will emit a soft chirp, and sometimes call in groups. Females typically lay 3,000 to 8,000 eggs and larvae development takes two to three months or more.
Endangered Status: The boreal toad is listed as endangered in the state and is a candidate for listing under the federal Endangered Species Act. Once very common in the mountains of Colorado, the boreal toad underwent a severe decline in distribution and abundance from the 1970s to the 1990s. Because the causes of the decline have not yet been identified, many questions need to be answered before the boreal toad can be helped toward recovery. The Division is currently investigating potential causes of the declines and reintroduction methodologies. One development was the the discovery of a deadly fungus present in local boreal toad populations. Chytrid fungus has been linked to the decline of amphibians in Australia and Central America has been confirmed in a population of endangered boreal toads west of Denver. The discovery of the fungus by a Division researcher who has extensively studied the rare toad population in Clear Creek County could lead to important new information on why toads, frogs, salamanders, and other amphibians have been disappearing at sites around the world.

River Otters

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Description: The river otter is the longest of our weasels, ranging from 3 to 4 1/2 feet, of which the powerful, cylindrical tail (which thickens toward the base) comprises about one-third. Webbed toes and water-resistant fur suit the animal to a life spent largely in water. Otters are rich brown in color, with silver brown beneath. Otters make many different sounds. They will chatter, chuckle, grunt, snort, and growl. They also warn other otters of danger with a shrill whistle.
Range: Otters can be found on every continent except Australia and live anywhere in the United States except Hawaii.Once otters probably occurred in major streams statewide in Colorado, although they apparently have never been abundant. Otters love to travel and can have a home range of anywhere from 5 miles to 47 miles from "home". River otters are aquatic, but they may travel several miles over land to reach another stream or lake. They are very sociable animals and usually travel together in groups of two or more.With settlement, subsequent water population and control of streamflows, otters disappeared from the state by the early part of this century.
Habitat: Otters live in riparian habitat, where aquatic animals like crayfish, frogs, fish, young muskrats, and beavers are favored foods. Otters usually live in bank dens abandoned by beavers. They are active mostly at dawn and dusk, and appear to spend large amounts of time just playing, sliding on ice, snow and mud, and swimming gracefully for no apparent reason beyond swimming.
Diet: Otters are carnivorous. They eat a variety of foods, including fish, crustaceans, amphibians, snakes, water insects, snails, worms, small mammals, birds, and eggs, frogs, turtles, and any aquatic invertabrates when they are in the wild. During the winter months, otters will move to a place where the water moves so ice does not form and they can hunt and fish. Otters will always wash themselves after every meal.
Reproduction: Otters breed in spring. Embryo impantation is delayed until the following winter, and one to four young are born in early spring. While the female is nursing one litter, mating occurs again. The babies are blind for five weeks and have no teeth when they are born. Baby otters are called pups and, they will stay with their mother for about one year and are taught to swim at age two. Sexual maturity is attained at two years of age.
Status: River otters used to be widespread through North America, but their numbers have decreased. Because of habitat loss and chemicals such as PCB's and the pesticide DDE, their population has dramatically decreased. Otters are not officially endangered but they soon started disappearing from their range soon after the Industrial Revolution. Although never being abundant in Colorado, river otters disappeared from the state by the early part of this century. In the 1970s, however, the Colorado Division of Wildlife began to restore populations to several drainages in the state, including the Upper Colorado, the Dolores and the upper South Platte rivers.

Wolverines

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Description: Wolverines have a reputation larger than life, but they are very impressive weasels. Wolverines measure 36 to 44 inches long, including a 15 to 18-inch tail. Otters are longer, but wolverines are the heaviest of weasels, tipping the scale of 20-30 pounds are more. They can get up to 50 pounds, which is the maximum weight. Females are 10 percent smaller and around 30 percent lighter than males. Their fur is dark brown to black, and the sides have a characteristic yellowish brown to whitish stripe. Like other weasels, wolverines have anal musk-producing glands. Its feet are very large for its body, and has webbed toes. Long, thick fur grows over the soles of its feet during the winter. The wolverine is the largest member of the weasel family.
Range and Habitat: Wolverines are mammals of the dense forest, in both North America and Eurasia. Wolverines generally live in forested and alpine habitats, but can live in almost all habitats seasonally, from mountainous areas to lowlands. In Colorado, historical and recent reports show nearly all wolverines are from higher elevations, in areas of heavy timber. However, wolverines may follow their considerable appetite into open country.
Diet: By day, wolverines rest in an informal den beneath a boulder or windthrown tree. By night they wander to eat rodents and carrion. Wolverines are omnivores and will eat almost anything. Occasionally they may eat weakened deer or other large prey, especially when bogged in deep snow. Males may travel 40 miles a day in search of food.
Reproduction and Life Cycle: Wolverines breed during the warmer months. They reach sexual maturity at two years old. Their gestation period lasts about 60 days. Females give birth to two to four young in winter or early spring. Kits weigh less than a pound at birth. Kits nurse for 8 to 10 weeks, and stay with their mother for two years. Wolverines generally live to be 8 to 10 years old. Males will live in around a 240 square mile radius, while females might occupy a territory up to 50 to 100 square miles.

Grizzly Bears

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Description: The grizzly bear is the largest of North American terrestrial carnivores. Grizzly bears are unmistakable, not only because of their large size (to 7 feet long, and weighing 500 pounds or more), but due to conspicuously humped shoulders, front legs longer than rear legs, a dished-in face, and front claws over 4 inches long. Color is mostly yellowish to reddish brown.
Diet: Grizzlies are too large and hungry to be picky eaters. They eat carrion (once commonly of bison), fruit, young shoots, roots, bulbs, fish, and larval and adult insects. They seldom chase down adult hoofed mammals, but do take elk calves and fawns they stumble upon. Sometimes they excavate marmots and other rodents.
Reproduction:Grizzlies breed in July. Embryo implantation is delayed, and after a gestation period totaling 26 weeks, the young (usually twins) are born to the hibernating sow in her winter den. Mother and cubs emerge from the den in April or May. The young are weaned in early autumn. Females first breed at 3 1/2 years and thereafter produce cubs every second or third winter.
Status: The grizzly bear is classified as an endangered species in Colorado, but it probably is gone from the state. Once they occurred throughout Colorado, and they were fairly common in the western three-fifths of the state at least until the turn of the century. After 1900, populations declined rapidly and no grizzly was killed in the state from 1952 until 1979, when naturalist learned that a grizzly was killed by a hunting guide in the San Juan Mountains, apparently in self-defense. Some have argued that because grizzly bears are native to Colorado's wild lands they should be re-established here, but the Colorado Wildlife Commission is on record as opposing restoration.

Gray Wolves

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Description: Wolves are large dogs, up to 5 feet long (of which 14 inches is a bushy tail). The color is pale gray washed with a buff and overlain on the back and legs with black. Sometimes called "timber wolf," to distinguish it from coyotes, or "prairie wolf," wolves actually occupy a wide range of habitats.
Range: The gray wolf ranges across Eurasia and in North America from the Arctic to Mexico and from coast to coast. Once distributed statewide, the wolf is gone from Colorado.
Diet: Once wolves fed on the vast herds of bison, elk and deer, supplemented by rabbits, rodents, and carrion. When market hunters decimated the large mammals that were their staple diet, wolves naturally turned to a new food resource in the developing frontier: Livestock.
Habitat/Reproduction: Wolves den in burrows in banks where the female bears 6-10 pups in March after a nine-week gestation period. The male provide food for the nursing mother. A pair may have a hunting territory of 10 square miles.
Status: Because of their depredations of domestic animals, wolves in Colorado were systematically eradicated by shooting, trapping, and poisoning. The gray wolf is an extirpated species in Colorado. An extirpated species is an animal that no longer exists in the wild in its historical habitat, but still exists elsewhere. Although gray wolves no longer exist in the wilds of Colorado, they can be found in captivity in zoos and wildlife parks.

Kit Fox

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Description: The kit fox is a small mammal of the Southwest desert weighing only about three to six pounds. They closely resemble swift foxes found on the eastern plains of Colorado, but have larger ears and a more angular appearance. They have long, black-tipped, bushy tails, dark muzzles, and a yellow-gray grizzled coat. They typically reach 3.5 to 5 pounds, making them about the size of a full-grown jackrabbit.
Range: The mammals can be found in Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas, Utah, southern Idaho, southern Oregon, and central Mexico.
Local Distribution: In Colorado, kit foxes live in the semi-desert shrub lands extending from Montrose to Grand Junction.
Habitat: Kit foxes occupy sparsely-covered, semi-desert shrublands of saltbrush, shadscale and greasewood. They spend most of their days in dens that are scattered around the landscape and which are very important for raising young and avoiding predators, such as coyote. Kit foxes generally live in small groups, digging clusters of dens with multiple entrances. The animals move from one den to another and emerge at night to hunt.
Diet: The fox primarily prey on cottontail rabbits, jackrabbits, and kangaroo rats, but they will also eat birds, reptiles, and insects when prey is scarce.
Reproduction: Dens are scattered within their territories. Kit foxes are active year-round and mate sometime between December and February. Gestation lasts just under two months, and litters contain four or five pups.
Status: The kit fox is listed as endangered in Colorado, and is considered one of the state's most vulnerable animals with only about 100 in residence. Conversion of the kit foxes' native grounds to agriculture and development usage has resulted in a loss of habitat. Predation by coyotes, road-kill, trapping, shooting, and predator poisoning are the main causes of mortality for the foxes. Once a furbearer in Colorado, the kit fox has been protected since 1994.

Black-footed Ferrets

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Description: Black-footed ferrets are large weasels, about the size of a mink, 18-22 inches long with a 4-6 inch tail. In color, they are yellowish brown above, with a blackish wash on the back, black feet and a face mask, and a black-tipped tail. They are difficult to distinguish from domestic ferrets, but they are larger and heavier than the long-tailed weasel (which in Colorado seldom has a face mask).
Range/Habitat: Black-footed ferrets seem to never to have been abundant in Colorado. They range statewide.Their habitat includes the eastern plains, the mountain parks, and the western valleys-grasslands or shrub lands that supported some species of prairie dog, the ferrets primary prey.
Diet:
The black-footed ferret is a predator, and its diet usually consists of animals. About 90 percent of their diet is prairie dogs, while the remainder includes mice, ground squirrels, rabbits, rats, birds, and even reptiles and insects.
Reproduction: Females do not exhibit the delayed implantation of embryos typical of the weasel family. Instead they mate in early spring and give birth to a litter of three or four mouse-sized pups after a seven-week gestation period.
Status: The black-footed ferret is listed as an endangered species in Colorado. Black-footed ferrets are reported to be killed by owls and coyotes. They are susceptible to distemper, and vehicles have killed them. However, it is reasonable to assume that plowing the prairie for agriculture and programs to eradicate prairie dogs drove the black-footed ferret to the verge of extinction.

Whooping Cranes

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Description:The adult whooping crane is white overall with red facial skin. In flight, black primaries are apparent. Immature birds are white with pale red-brown head and neck and scattered red-brown feathers over the rest of the body. Adult whooping cranes are 50 to 56 inches long and have a wingspan of 87 to 90 inches. Males weigh 16 pounds, females weigh 14 pounds. They can have a wing span up to 7.5 feet. The bird is distinguished by its outstretched neck in flight. It has a shrill trumpeting ker-lee-loo call. Common names are a whooper, big white crane, flying sheep, stork and white crane.

Range: Whooping cranes are endangered both state and federally. Historically, the birds nested over a wide area from Lake Michigan northward to the Arctic coast and wintered along the coasts of Texas and Louisiana. But populations have decreased dramatically since the 1900s. In Colorado, whooping cranes can be seen in the San Luis Valley for four to six weeks during February and March and in the western valleys, especially Mesa, Delta and Gunnison counties.

Habitat: They live in mudflats around reservoirs and in agricultural areas. While wintering, they live on salt flats that are dominated by coastal salt grass. Their nesting grounds are wetland communities dominated by bulrush.

Diet: Whooping cranes are omnivorous feeders. The most common foods are crabs, clams, shrimp, snails, frogs, snakes, grasshoppers, larval and nymph forms of flies, beetles, water bugs, birds and small mammals. They eat more than 58 species of fish.
Reproduction:Whooping cranes breed during the summer. The birds arrive on breeding grounds in late April. Whooping cranes are monogamous and form life-long pair bonds. The female lays two eggs, two days apart, during late-April or early-May. The incubation period is 29 to 34 days. Currently, breeding birds number about 100 and there are 260 individuals - 150 in the wild and 110 in captivity. Whooping cranes begin to acquire adult plumage after the first summer. They fledge for 78 to 90 days. The young are abandoned by their parents the following spring and are sexually mature at four to six years of age. In the wild, whooping cranes typically have a lifespan of 22 to 24 years. In captivity the lifespan is increased to 27 to 40 years.

Status: The whooping crane is considered an endangered status. It has managed to fight off the threat of extinction for the last half century. Whooping cranes historically nested over a wide area from Lake Michigan northward to the Arctic coast and wintered along the coasts of Texas and Louisiana. Populations decreased dramatically throughout the 1880s and into the early 1900s, mainly because of the loss of nesting and wintering habitat. Some were also killed for their feathers. By the early 1940s, reports indicated that the population had dropped to less than 20 birds, and extinction appeared imminent. But a stringent management program may have saved the species. The program called for the protection of the birds' nesting area at Wood Buffalo National Park in Canada and their wintering area at Arkansas National Wildlife Refuge in Texas. Two other management programs have also been attempted. One called for raising birds in captivity, and another was aimed at establishing a wild population in Idaho. In Colorado, whooping cranes occur only as migrants, stooping over in the San Luis Valley on their way to and from their wintering grounds.

Peregrine Falcons

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Description: Peregrines belong to the falconidae family. Peregrines are a medium-sized falcon characterized by a nearly black helmet, a dark, slate-blue back and buff broken by horizontal bars on the underparts. Adult peregrines vary in length from 15 to 22 inches. Like all falcons, it has long, pointed wings and quick, steady wing beats in flight. The peregrine falcon is one of the fastest creatures on earth, because they can swoop down on prey at speeds reaching 200 miles and hour. There are two subspecies of peregrine falcons-the American (anatum) and the Arctic (tundrius). Arctic peregrines migrate through Colorado. The American breeds and nests here.
Range: Peregrines have an extensive ranger worldwide, occurring on all continents except Antarctica and on many islands. They breed from Alaska and the Canadian Arctic south through the mountainous western United States and sparingly in the east. Peregrines winter on the coast north to British Columbia and Massachusetts, and in South America.
Local Distribution: In Colorado, the falcons can be found from the Front Range to the state's western border.

Habitat:Peregrines often live in remote and rugged terrain, in places we can only look up at and marvel.

Diet:Peregrines hunt most vigorously at dawn and dusk in open areas, such as shores, marshes, and valleys. They are predators, and eat mainly other birds. Often times, their prey is unaware they are about to be attacked, because peregrines can travel at speeds up to 200 miles per hour. Peregrines will usually strike in mid-air, knocking their prey to the ground.

Reproduction: Peregrines will pick their mate for life around 3 years of age, staying together when they are not even breeding. Most of the time they will nest in rocky cliffs or abandoned eagle nests. The nests are often times no more than a depression dug out of the rocks and gravel. Up to four eggs are laid in the nests, which are incubated mainly by the female. Young chicks will hatch in about a month, which are light colored. The chicks will fledge a little more than a month later.

Status: The peregrine falcon is considered an endangered species. There are few natural predators for adult peregrines. Man is the peregrine falcon's greatest danger. Because of the pesticide DDT, falcon populations disappeared in many parts of the world. By the mid 1960's, there were no peregrines in the eastern United States. The decline spread westwards so that by the middle of the 1970's, western populations had declined by up to 90 percent. Because of successful reintroduction programs, peregrine falcons now exist all over the United States.

Colorado Native Fish

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Note:There are many species of fish native to Colorado. Some are endangered and some are threatened. There are too many to go into detail on this page, but if you want to see the complete list, you can go to the Colorado Division of Wildlife Threatened and Endangered page, or scroll down to the end of this page and click on their link.