The food of the meadow mouse is chiefly vegetation: grass, foliage, seeds, twigs, roots and bark and at times they may become very destructive to field crops and orchards.
This little animal is very prolific and usually has several litters each year, with each litter consisting of from four to eight young. Were it not for their many enemies they would soon overrun the grass lands and do untold damage. As it is, their enemies, which are practically every predatory animal and bird, can barely keep them in check. Meadow mice serve as a valuable source of food for the smaller predatory animals such as coyotes, foxes and for the various hawks and owls.
There are four species of these mice that have been found in Yellowstone Park:
Sawatch Meadow Mouse: Microtus pennsylvanicus modestus. A medium-sized mouse with upperparts dull ochraceous, sprinkled with black. Underparts soiled whitish to ashy or cinnamon. In winter many black hairs along upperparts and underparts with wash of creamy white. Total length 7 inches, tail 1.8 inches. Has been found at Mammoth Hot Springs, Upper and Lower Geyser Basins and Shoshone Lake.
Dwarf Meadow Mouse: Microtus montanus nanus. A small-sized, rather short-tailed mouse with upperparts everywhere mixed gray, sepia and blackish, feet grayish; tail bicolor, dusky gray and whitish; underparts whitish. Total length 6 inches; tail 1.6 inches. Found in the grass of meadows and upland slopes over most of the park and appear to be the most abundant and generally distributed of the meadow mice in the park.
Cantankerous Meadow Mouse: Microtus longicaudus mordax. Resembles Sawatch meadow mouse in size but the tail is longer, ears larger, and color grayer. Upperparts grayish bister; sides grayer, underparts whitish. Lighter colored in the winter. Total length 7.4 inches; tail 2.8 inches. These mice have been found at Mammoth and Tower Fall and are probably common in most of the meadows of the park, equally at home on dry ground or in mountain streams.
Big-footed Meadow Mouse: Microtus richardsoni macropus. Largest of the meadow mice. Total length 8.8 inches; tail 2.8 inches. Upperparts dark sepia mixed with black, sides paler, feet gray; tail bicolor sooty whitish; underparts washed with silvery-white. In winter grayer above, more white below. Usually found close to water where they swim much in the manner of muskrats. This mouse had been taken at Heart Lake and its runways seen in marshy meadows of most of the western part of the park.
Pack Rat or Trade Rat is the name commonly applied to this individual, represented in the park by both of the above forms. Pest of the stations and patrol cabins because of his fondness of getting into buildings and collecting items of every description, especially those of shiny appearance. These are packed to his nest, which is located either in rock piles, cliffs or whenever possible in or around buildings. He cuts open food containers, bedding and other contents and makes a general mess.
He frequently leaves some object in place of the stolen article, hence the name trade rat. However, this trade is probably due to his dropping something that he was already carrying, when he spied the new object that was more attractive, rather than any desire to make a fair trade. They gather anything that is of a convenient size to carry.
The wood rat is a very clean animal, of no relation to the common barn rat except in superficial resemblance. A vegetarian in diet he lives on green vegetation such as grass and foliage, fruit, bark, roots, fungi, seeds and nuts. He is active all year but seldom accumulates much of a store of winter food.
Mainly nocturnal in habit, they are, however, occasionally seen in the daytime. Their principal enemies here are hawks, owls, weasels, coyotes and martens.
The young, from three to six in a litter, are born in June or July and are duller in color than the parents.
General description: Large in size, mouse-like in appearance. The fur is fairly long, soft and grayish buff in color, darker in the Colorado form, on the upperparts, white underparts and feet, and a large, bushy, flattened almost squirrel-like tail. Total length 15 to 16 inches. Sexes equal in size.
Wood Rat or Rock Rat
Where found: Throughout the park. The gray wood rat mainly in the transition zone in open country along the Yellowstone, Lamar and Gardner Rivers and around Mammoth. Colorado wood rat in higher portions of the park.
Quiet streams or the shallow grassy margins of ponds and lakes are the home of this valuable little fur-bearing animal. More valuable than many people realize since few know that he is the Hudson Seal and other trade names of our popular fur coats. Ironically, muskrat fur is used as an excellent imitation of his greatest enemy, the mink, in the mink-dyed muskrat coats.
A hardy little animal that lives much like the beaver, in bank dens with underwater entrances or in dome-shaped houses made of rushes, grass, turf and mud instead of the coarser sticks and branches used by the beaver. In these houses or bank dens they spend the winter in comfort. Remaining active all of the year and seldom storing any food, muskrats are out in the coldest weather.
Their food consists of bulbs and tubers, roots, tender portions of numerous marsh and water plants, sedges, grass and clover, and possibly some small aquatic animal life, salamanders, etc. In the winter it is sometimes necessary to make extensive excursions under the ice in search of food.
Muskrat
The young are born in the house or bank nests in May or June, usually six or eight in a litter. In lower, milder sections more than one litter is raised during the year. Fortunately muskrats are prolific breeders.
The name muskrat originated from the fact that there are two glands near the base of the tail that contain the strong though not unpleasant musk, which may be left at intervals about his haunts possibly as signs or marks of possession. While several may use the winter house the muskrat is ordinarily rather fussy and gets into frequent fights over territorial rights.
General description: A rather large, robust, somewhat rat-like appearing animal, with short legs and broad feet, the hind ones partially webbed; tail long, scaly and sparsely haired, flattened laterally. Ears scarcely showing above fur which is dense with longer guard hairs. Upperparts are dark brown, underparts lighter in appearance. Total length 23½ inches, tail 10 inches; weight about two pounds.
Where found: Throughout the park along moving streams, like the Yellowstone River between Lake and Canyon, and most of the ponds and lakes. Frequently working in the morning and latter part of the afternoon as well as at night.
This little Pika, Cony or Rock Rabbit of Yellowstone is in reality a diminutive, tailless rabbit. Common in the higher elevations wherever loose rock piles and slides offer suitable locations for his home.
Timid and secretive in nature and possessing a protective coloration that makes them hard to locate in their rocky homes, the pikas are not often noticed by the majority of park visitors. The call of a pika, a squeaky bleat, has an elusive quality that confuses the hearer as to the direction in which it originated.
The best indications of the habitation of the pika are the small stacks of hay among the rocks. He is an industrious little farmer and is usually busy during the summer cutting and curing grass and plant foliage for winter use. This material is first put in the sun to cure, then piled in sheltered places among the rocks where it will be accessible during the winter when the snow has made a protective blanket over the landscape. In protected cavities and runways beneath the rocks, with an ample supply of hay, the pika has nothing to worry about during the winter months and find no need to hibernate. Just what family activities they have during this period is not known.
If an observer remains quiet near their rocky homes he may soon be rewarded by a sight of them running silently about over the rocks, and it may occasionally be possible to approach close enough for a picture.
The young, from three to five in number, are born from late May or early June to early September. Due to their secretive nature and the location of their homes not a great deal is known yet about the home life of the pika.
General description: A short, chunky, apparently tailless rabbit-like animal, ears rounded and of good size; legs short and hind legs very little longer than forelegs. Color of upperparts grayish to buffy, underparts whitish varying to cinnamon-buff. Sexes alike in color and size; about 7½ inches long, height to shoulder 3½ inches and weight 4 to 7 ounces.
Cony or Pika
Where found: Distributed throughout much of the park at elevations above 7,000 feet wherever rock slides and talus slopes are available. Most likely seen around the Golden Gate, Sheepeater Cliffs, cliffs south and west of the Upper Geyser Basin, rockslides along the Dunraven Pass road and other such places. Look for the hay piles as indications. Active during the daytime.
This shy and timid little rabbit leads a precarious existence in the sagebrush-covered valleys of the lower portions of the park. Its numerous enemies, especially the coyotes, foxes, bobcats, hawks and owls keep the cottontail constantly on the alert and seldom far from dense thickets or sheltering rocks. Its short legs are not a match for the speedy coyote and so artful dodging and hiding tactics must be resorted to.
The mother cottontail makes a nest, lined with her own fur, in a sheltered place where the young, born blind, naked and helpless, are placed. They grow rapidly and are soon able to run about and play, then it isn’t long until they are out on their own. There are usually several litters born each year; this helps keep up their numbers in spite of the inroads made by the various enemies.
Cottontail
General description: A small rabbit with short ears and legs. Upperparts of creamy-buff color lightly grizzled with gray. Tail short and fluffy, gray on top and white on underside. Total length 15 to 16 inches.
Where found: Most likely to be seen near Mammoth and in sagebrush flats along the Gardner River. Mainly found in the transition zone and lower. Most frequently out in the early morning, evening or during the night.
The Varying Hare or Snowshoe Rabbit is found throughout the higher parts of the mountains, fairly common but not abundant in numbers. Provided by nature with special adaptations, this rabbit is not bothered greatly by the winter storms and snow. Very large furry hind feet act as snowshoes enabling these rabbits to scamper readily over the snow without sinking in and thus are the basis for its common name.
Nature also provides these hares with a camouflage to help protect them from their enemies. Their summer coat of fur is dull brown in color which blends well with the forest floor, while in the winter they get a new coat of pure white, except for black ear tips, making them hardly distinguishable from the snow drifts over which they run. This varying color with the seasons is the source for the other name by which it is known.
These rabbits, like other members of the family, depend upon the foliage of plants and shrubbery as their principal food; however, when this is buried beneath the winter’s snow their diet is frequently mainly composed of the bark of bushes and small trees.
The snowshoe rabbit makes a nest in a sheltered place, where the young, usually three or four in number, are born. These young, unlike the cottontail, have their eyes open and are covered with a coat of very fine close hair. They leave the nest in about ten days. In some places there may be more than one litter in a year.
General description: Larger than a cottontail with long ears and hind legs. Color of upperparts (summer) buffy grayish brown to rusty brown, underparts and bottoms of feet white; (winter) white, with black-bordered tips of the ears and underparts pale salmon. Total length about 18½ inches.
Varying Hare (Snowshoe Rabbit)
Where found: Likely to be seen almost anywhere in the wooded sections of the park and near the camp and cabin areas. Especially during the early morning and evening. They are generally rather tame.
This big Prairie Hare is readily distinguishable from the other jackrabbits by its all white tail. It may also be found at higher elevations than the other species of jacks. Normally frequenting the open country it has been seen in alpine meadows above timberline at 10,000 feet elevations. This species is the largest of the jackrabbits.
All of the jackrabbits are known for their speed as they go bounding over the prairie, covering twelve to fifteen feet at a jump. The whitetail is the fastest and best jumper of the lot. When in high-gear speed he is a match for all but the fleetest of greyhounds.
The whitetail jackrabbit makes little if any nest for the young, but like other rabbits, does have several forms scattered about his home range. The form is simply a place just large enough to accommodate his body, padded down and hollowed in a clump of grass, weeds or bushes. Each individual has several of these forms and when not out feeding or playing may usually be found crouched down in one or the other of them. The young are fully furred and have their eyes open when born. They are active but stay hidden close by one spot for the first two or three weeks. There are usually about four to the litter and there probably is more than one litter each year, at least in the warmer sections of their range.
The representatives of this species that live in the northern, colder parts of the country change into a winter coat of white fur each fall and like the snowshoe rabbit are protectively colored when out in the snow. Their large feet also aid them in traveling over the snowdrifts.
General description: A large, heavy bodied rabbit with large ears, long legs, and a good sized fluffy tail that is all white throughout the year. The color above is fairly uniform buffy gray, underparts white. Its winter coat is much the same as the summer, though paler in tone, except in the northern parts of the range, which includes Yellowstone, where it becomes pure white with black tipped ears and irregular buffy patches about the face. Total length 24 inches.
White-tailed Jack Rabbit
Where found: Open sections in the northern parts of the park. Has been seen on the highest slopes of Mount Washburn. Most frequently seen in the early morning and evening. Not numerous.
The following animals are also found in the park area:
Bangs Flying Squirrel: Glaucomys sabrinus bangsi. A medium-sized squirrel, total length about 12.5 inches. Upperparts dark grayish cinnamon; underparts pinkish cinnamon.
These squirrels are strictly nocturnal and for this reason it is difficult to tell how common they really are. Found only in the forested areas they nest in woodpecker holes or in hollows in the trees or possibly build a nest among branches or utilize old pine squirrel nests when hollows are not available.
Probably common throughout most of the forests of the park.
Mountain Weasel: Mustela frenata arizonensis. A medium-sized weasel about 14 to 15.4 inches long. Upperparts raw umber-brown, darker on the head; underparts yellow to orange with a white chin. In winter the animal is all white with a black tip on the tail.
Frequenting the more open ground in the park they live primarily on rodents. In the winter they hunt beneath the snow. I have seen them stick their heads up through the snow, look around and quickly dive beneath again.
Dwarf Weasel: Mustela streatori leptus. A very small weasel with a total length of not over 9.8 inches. Upperparts dark brown; underparts white. In winter it is white with black tip on the tail.
Seldom seen but is probably found in most of the open sections of the park as it is common on all sides.
Weasels are strictly terrestrial and are very highly carnivorous and blood thirsty. Very active and courageous attacking without hesitation animals considerably larger than themselves. They have very slender, long bodies and short legs.
Northern Plains Skunk: Mephitis mephitis hudsonica. A large skunk with a large bushy tail. Black in color with a broad white stripe along each side of the back extending from nape of neck to base of tail.
Reported as common in the lower northern valleys along the Gardner, Yellowstone and Lamar Rivers and occasional in other inland valleys by Bailey in 1923.
Longtail Red Fox: Vulpes fulva macrourus. This species has a longer tail than the average red fox. In color it is a reddish yellow to golden yellow with grizzled whitish; underparts white; feet and lower part of legs black.
The red fox although not common is occasionally seen in the north and northeastern sections of the park. It was at first regarded as rare but seems to be increasing somewhat in recent years.
Mountain Bobcat: Lynx rufus uinta.
Canada Lynx: Lynx canadensis. These two animals are very similar in habits though the lynx is more a dweller in the colder forest regions while the bobcat may be found in more open areas closer to habitation. Both have tufted ears and a short tail and neither of the above species has the distinct spots that are characteristic of some of the species of bobcats. The lynx is the largest of the bobcats and is slightly larger than the mountain bobcat. The bobcat has a tail seven or eight inches long with two black bands on the upper surface in front of a black tip while the lynx has a tail only about four inches long and with black only on the tip.
These animals are rare in the park area and have only been recorded in the northern section. My only observation of one was about eight miles north of the park along the Yellowstone River.
Wolverine: Gulo luscus. Heavily built animals with short legs, short ears, a short bushy tail, and long coarse hair. Appearing much like a small, short-legged bear. Total length is from 37 to 41 inches and weight from 22 to 35 pounds. It is dark brown or blackish in color with two broad, pale, lateral bands of brownish white to yellowish white from shoulder to rump.
The wolverine is a powerful and savage fighter, strictly carnivorous and well earns its name of “glutton.” It had a bad reputation among trappers for it followed their trap lines, robbed and even broke up their traps and dug up their food caches. Wolverines are no longer common in this part of the country and while there may have been a number of them in the park area some years ago they are probably only very rare visitors now.
Brown Pocket Gopher: Thomomys talpoides fuscus. The piles of dirt which suddenly appear in the grass of lawns or meadows are made by the pocket gopher. He excavates a network of tunnels below the sod line, pushing the dirt through an opening on to the surface, then filling the opening up again. Their food consists of vegetable matter such as roots, bulbs, tubers and surface foliage and green vegetation.
The pocket gopher is rather small in size, about eight inches long, including a tail of a little over two inches, and is light brown in color. The tail is only sparsely haired and the front feet are large and built for digging. The Uinta ground squirrel or picket-pin is frequently referred to by some people as a gopher, but it should not be confused with the true gopher and is seldom seen above the ground.
Found in meadows and open areas throughout the park.
Rocky Mountain Jumping Mouse: Zapus princeps. Sometimes called Kangaroo Mouse this little animal is a medium-sized mouse with greatly elongated hind legs and a slender tail nearly six inches long. Its upperparts are yellowish brown lightly sprinkled with blackish, the underparts white.
This mouse lives on vegetation and seeds. It is found throughout the park in meadows and open country but nowhere abundantly. It hibernates during the winter.
Gale Redback Mouse: Clethrionomys gapperi galei. These mice live on green vegetation, seeds, roots and stems and probably occupy most of the forested sections of the park. They live in burrows and are not very often seen. Several have been trapped in residences in Mammoth. They are active all winter under the snow.
They are small to medium sized mice with the upperparts reddish chestnut distinctly differing from the buffy gray sides; underparts whitish to yellowish gray.
Dusky Shrew: Sorex obscurus.
Mountain Water Shrew: Sorex palustris navigator. Most species of shrews are smaller than any mice, with pointed noses, minute eyes, and small ears which are hidden in the fur. They are insect eaters and like any kind of fresh meat. They are active all winter.
The dusky shrew is a sepia brown in color and is found throughout most of the park area. Mountain water shrews make their homes in banks of icy streams and are mouse-size with upper parts slaty mixed with hoary. They have larger feet than the dusky shrew and have bristly fringes along the toes with partial webs which equip them for swimming readily.
The Rocky Mountain Shrew (Sorex vagrans monticola) has been collected once in the park and it is also probable that the Masked Shrew (Sorex cinereus) is also here as it has been found in the surrounding area.
According to Bailey, Yeager and others the following bats have been found in the park during the summer, all migrating south for the winter:
Big Brown Bat: Eptesicus fuscus
Numerous over the central plateau section.
Hoary Bat: Lasiurus cinereus
A few range over most of the park.
Long-eared Bat: Myotis evotis
Numerous in the lower portions of the park.
Silver-haired Bat: Lasionycteris noctivagans
Fairly numerous in timbered areas.
Yellowstone Bat: Myotis lucifugus carissima
Numerous over most of the park and especially at Lake and around the Devils Kitchen at Mammoth.
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