Part 11

Description: A small rodent, two-toned in color, that leaps through the grass much like a kangaroo rat. Total length 8 to 10 inches. Tail 4½ to 6 inches. Color buffy along sides, shading to almost black on the back and white on the underparts and feet. Tail bi-color, dark above and light gray beneath. Ears relatively long, dark in color with light buffy marginal lines. Eyes beady, set in long face with sharp nose. Front legs short but hind legs and feet large and muscular. Young, four to six in a litter, with no more than one litter a year in the higher elevations.

The jumping mice are among the most specialized small rodents in the United States. The genus is typically North American, only one species being found outside this continent. At some time in the distant past this little creature adapted itself to a mode of flight much like that of the kangaroo and jerboa. In this respect it exceeds the kangaroo rats and pocket mice of the United States, species to which it is distantly related. Its general build is distinctly like that of the kangaroo, with the same delicately formed front quarters and heavier hind quarters. The tail, though not club-shaped like the kangaroo’s, is long enough to serve the same purpose—that of a rudder to guide the direction of flight. The hindlegs are muscular enough to propel the body on proportionally longer jumps than even the kangaroo. Here the resemblance ceases, however, for the jumping mouse is not related, even distantly, to this marsupial. The only pouches the jumping mice have are internal cheek pouches used exclusively for transportation of food.

Jumping mice have one more peculiarity that set them apart from most other North American mice; they hibernate. The period of hibernation is not a short one at the elevations at which these mice live. It may last for as long as 6 months. Preparation for this extensive period of inactivity consists mainly in gathering and eating grass seeds until a thick layer of fat is stored under the skin. With the first cold weather the jumping mice retire to previously prepared underground burrows and sleep the winter away.

Since they are almost exclusively seed eaters, they may have a difficult time on emerging in the spring. Apparently there is no food cache stored away for this period, so the hapless rodents must search for what can be found until the grasses head out again. The method of harvesting grass seed is unique, and once seen will not be easily mistaken. Living as they do in a jungle of tall grass, they are not able to reach the heads nor to climb the slender stems. Instead, they cut off the stem as high as they can reach, pull the upper part down to the ground and cut it again. This goes on until the head is brought within reach. Small piles of grass stems, all cut to an average length, indicate that this is the species which has been at work.

Jumping mice seldom will be seen except when in flight. Then their jack-in-the-box tactics make it almost impossible to determine what they are really like. They are timid, inoffensive little creatures which, if caught, will seldom offer to bite.

Bushy-tailed woodrat Neotoma cinerea (Greek: neos, new and temnien, to cut ... Latin: cinereus, ashy)

Range: Mountainous portions of western North America from Alaska south to central California, northern Arizona and New Mexico.

Habitat: Found usually in association with the pines of the Transition and Canadian Life Zones; crevices in cliffs and among rock slides are favorite nesting sites.

Description: This woodrat will be recognized at once by its bushy, squirrel-like tail. The several other species in the same range have the usual scanty growth on the tail, so thin as to be almost unnoticeable. This species is large for a woodrat; total length ranges from 12½ to 18 inches. Tail 5½ to 8 inches. The soft, thick fur shows wide variation in color, as might be expected from the great range occupied by this species with its many subspecies. In general it varies from ashy to cinnamon above, to pure white on the underparts. Although the head has the same general shape as that of other woodrats, its appearance is altered somewhat by long, silky whiskers up to 4 inches in length, and extremely large ears. The dark, beady eyes, however, are typical of the genus. The young, from two to six, are born in early summer. This average of four or possibly less, when the breeding habits of all the subspecies are taken into consideration, seems low when compared with other small rodents. The low death rate indicated probably is due not only to this species’ secretive habits but to a high order of native intelligence as well.

Many are the names applied to this interesting little animal. “Mountain rat,” “pack rat,” “trade rat,” and woodrat are some of the most common. Several stem from the supposition that when the animal takes an article that suits its fancy, it always replaces it with something which it supposes to be of equal value. Observation of the creature’s habits will indicate that these “trades” are entirely by chance. These animals are continually carrying small objects about and often drop one in favor of another more to their liking. The fact is that the most attractive items usually are carried to the vicinity of the nest, and so the scientific name of one of the subspecies is perhaps one of the most appropriate for this industrious collector. This subspecific title is orolestes, which translated from the Greek means oros, mountain, and lestes, robber.

The penchant for carrying away another’s property leads to many incidents both comic and tragic. The rats are not at all averse to sharing a prospector’s cabin, and during hours when the rightful owner is away at work raise havoc with his possessions. During long winter nights they are no less industrious, and the mysterious sounds of their activities will keep even a sound sleeper awake for hours. Eventually this becomes so exasperating that drastic action is called for. One old prospector told me of a woodrat that had been bothering him for a long time. Traps proved of no avail and finally one night he placed his forty-five on a box beside his bed, together with a candle and matches. During the night he was again awakened and quietly sat up and lighted the candle. There on one of his cupboard shelves was the dim form of the rat. Taking careful aim in the flickering candlelight, he pulled the trigger and hit the animal “dead center.” The heavy slug literally blew it apart. Unfortunately it happened to be sitting directly in front of a 5-pound can of coffee. One may assume that without either woodrat or coffee he slept soundly thereafter.

My own experiences with this species have been no less exasperating. When but a youth, my brother and I were quartered in an old bunkhouse one winter. We chose the smaller of the two rooms as being easier to keep warm, and after a thorough clean-up moved in. No rank novices, we wired our watches to a nail driven into the wall and hung our other valuables from a wire stretched across the room. In the morning our socks were missing! Thereafter matters were uneventful for a week. The woodrat would come up through a hole in the corner of the room as soon as the lights were out. All night long it would make trips through the connecting door into the adjoining room and carry away loads of cotton from an old mattress on the unused bed.

Came the week-end and the Saturday barn dance about 3 miles up the canyon. Fresh shirts and trousers donned, coats and vests were taken from the chair backs upon which they had been carefully hung. Behold! One vest front was completely chewed out and carried away, presumably for nesting material. This was the last straw; the creature must be done away with.

On the following night plans were laid with care. Two 5-gallon oil cans were placed in the doorway. This left a narrow passageway just wide enough to accommodate a small jump trap. A piece of newspaper was placed over the trap and the end of the chain wired to the head of the steel bedstead. A short time after the lights were put out, a scratching noise indicated that the animal had come in through the hole. All was quiet until its nose came into contact with one of the empty cans. Then snap! A series of squeaks and the rattle of the chain gave warning that the creature was climbing into bed. As it came in over the head, the wildly excited occupants left by the foot. When the light was struck the rat was sitting in the middle of the bed. A heavy boot soon dispatched it and a semblance of order again returned to the bunkhouse. Strange to say, no more woodrats came in for the remainder of the season.

Although such experiences are the rule when this rat has moved into a dwelling, it is a delightful creature in its native haunts. It is a rim rock dweller; that is, it likes best to build its nest far back in some deep crevice of a cliff. If such a location is not available it may find a protected site in a talus slope or even among the roots of a tree. Usually these natural fortresses are further reinforced by the addition of a pile of sticks and miscellaneous materials piled helter skelter over the nest. The nest itself is quite large, usually a foot or more in diameter, built of the softest and warmest materials at hand. Somewhere adjacent to the nest will be found one or more caches of food against the time when the snows are deep and famine stalks the land. As has been mentioned, the woodrat is usually associated with the pines of the Transition Life Zone and above, and pine nuts are one of its most popular items of food. Acorns, seeds, berries, stone fruits, and some vegetation round out its vegetable diet. It will also eat meat whenever available although, except for insects, shows little inclination to kill its own. With such a varied menu, it seems entirely proper to call this rodent omnivorous.

One of the most characteristic marks of the woodrat’s home is a strong, musky odor. This is not an indication of uncleanliness. The animal is most fastidious in its toilette but has this body odor in large measure. A study skin will retain a strong trace of it for many years. Whether it functions for an identification to others of the species is not known, but it could well serve this purpose.

Although classed as a nocturnal animal, the bushy-tailed woodrat is often active throughout the daylight hours. They are not gregarious creatures; yet, since suitable nesting sites may not be found in some areas, other more favored localities often will harbor considerable numbers of the animals. Overhanging ledges may shelter the piles of litter denoting a nest every few feet. In such cases, a well-worn trail will lead from one to the other. This is not an indication that a colony lives there in peace and harmony. These rats are truculent creatures among themselves, and if a stranger should venture into a nest mound, he is evicted with many indignant squeaks and a fearsome snapping of teeth. The interloper seems to know he is out of order and usually leaves the nest at once without more than a token show of resistance. In neutral territory such as a cabin, however, several woodrats may share the area quite peacefully, but to the great annoyance of the human occupant.

The variety of sounds produced by such a group is quite amazing. Added to the usual high-pitched squeaks and patter of running feet are the mysterious rustlings of paper and other objects being dragged about. A peculiar thumping sound indicates a gait which I have never seen but often heard at night. It must be somewhat like the leaping flight of a kangaroo rat, at least it indicates a swift succession of leaps across a flat surface such as a floor or roof. Perhaps the broad surface presented by the flat of the bushy tail is of assistance in this maneuver. Then, like most rodents, the woodrat will thump with its hind legs as an alarm signal. This is perhaps the most noticeable sound of all, for it marks the instant cessation of all activity for every member of its kind within hearing distance. The “ear-splitting silence” that follows this signal literally presses in on one in the darkness.

Muskrat Ondatra zibethicus (French Canadian word from the Iroquois and Huron Indian word for muskrat. Latin: the odorous substance of the civet alluding to the musk secreted by the muskrat)

Range: Virtually all of North America north of the Mexican border. Muskrats are found from near sea level to as high as 10,000 feet above it.

Habitat: This large rodent can exist only near a permanent water supply which is deep enough to shelter it from its enemies. This may be a lake, a marsh, or a running stream.

Description: A large aquatic rodent whose long, flat tail undulates from side to side when it swims. Total length 18 to 25 inches. Tail 8 to 11 inches. Weight 2 to 4 pounds. The thick, dark brown fur of the upper body is overlaid with brown to black guard hairs. The legs are short but powerful. The front feet are small, but the hind feet are relatively large and partially webbed, with stiff hairs on the edges of the webs and along the sides of the toes. The long, black tail is flattened vertically. It is so scantily haired that it may be said to be naked, but is covered with small scales up to 2 millimeters in diameter. The head is quite similar to that of a vole. The ears are so short as to barely protrude through the fur, and the eyes are small. Average number of young thought to be six per litter. Several litters may be born each year.

The presence of muskrats in a shallow lake or marsh is not difficult to detect. This is their chosen habitat, and here in water about 1½ feet deep, they build their characteristic mounds of rushes and cat-tails. Here they may also be seen on quiet days swimming about and carrying on their normal activities. In much of the Southwest, however, such favorite habitats are few and far between and the muskrats must take their choice, if there be one, between the few permanent streams and irrigation canals. In these altered circumstances they react quite differently; they may often be present in considerable numbers without anyone being the wiser. The change in habits required by this different environment illustrates the great adaptability exhibited by many of our most common mammal species.

The most important requirement of a muskrat is a permanent body of water of a depth sufficient for it to dive into and escape from its enemies. Given this, it will at once set about constructing a home. In a lake or marsh, there is little or no current. In sheltered bays, where wave action is slight, the bottom often will be muddy. In the shallow water along the shore, water plants such as tules and cattails will become established. This is indeed muskrat heaven, for these and other aquatic plants are both their food and building materials. The most edible portions of the plants are the roots and the stem portions which are below the surface of the mud. When one of these choice tidbits has been cut free by the muskrat’s sharp teeth, it is carried to some favorite place to be eaten. This may be a mud bar well sheltered by overhanging vegetation from prying eyes, the end of a log projecting above the surface of the water, or perhaps the roof of the “house.” The discarded portion of the stem is buoyant and usually lodges among the remaining plants until needed for building purposes.

When the muskrat house is being built, a great quantity of this flotsam is piled up until the resultant mound may project as much as 3 feet above the water and be 5 or 6 feet in diameter. The nest is built above the waterline in this half-submerged “haystack.” Entrance to the living quarters is by a tunnel which usually starts through the mud a short distance from the base of the house, goes under the edge of the structure, then inclines upward to the nest. Only one entrance is necessary for even if some enemy should tear through the tangle of rushes deep enough to reach the nest, it would take so long that every inmate could easily escape by this submarine route. The house serves one more important purpose in the far north. When the ice lies thick over the marsh and seals this water world away from air, the muskrats can still take short forays under the ice for food and return again to free air, without which no mammal can exist.

Had the muskrat learned to build dams such as beavers construct, the species might very well be near extinction in the Southwest, since such structures would seriously interfere with irrigation. However, since they have accepted conditions as they are, the muskrats do very well for themselves in the shallow streams and irrigation ditches. In fact, their population under the adverse conditions of today is probably far above that of the days before the white man arrived on the scene. Do not assume from this statement that a whole new way of life has been opened up for the muskrat. There has always been a “bank” muskrat that lived in burrows in the stream banks. This fast-water addict has now taken full advantage of the artificial streams that are the forerunners of agriculture almost everywhere in the Southwest. The burrows built into the canal banks seem to be identical with those constructed under natural conditions.

The “bank” muskrat builds three types of shelters, each with a definite and necessary function. These might be called the feeding burrow, the shelter burrow, and the breeding burrow, respectively. The first two are simple in design and have few variations, but the breeding burrow may be extremely complex. If a choice is available, all burrows will be in a bank along the swiftest flow of water, as on the outside of a curve in the canal, for instance. This prevents the entrances from silting shut as they would in the more quiet reaches.

There are two types of feeding burrows. The first and more common consists of a cut made just above water level in the side of a vertical bank. If possible, it is behind a portiere of hanging grass or weeds, so as to be completely screened from view. This is merely a safe place to which the muskrat can take its food and eat without being bothered by enemies. The second type of feeding burrow is more elaborate, consisting of several such chambers along the bank connected by short tunnels. These seem to be community shelters since they are used by several individuals at the same time. The added safety provided by the connecting tunnels seems to be the advantage in this type of dining room.