Part 12

For some reason, perhaps owing to their small size and defenselessness against birds and beasts of prey, the great majority of small mammals, including hundreds of species and untold millions of individuals, are nocturnal or live such obscure and hidden lives they are unknown except to the comparatively few people who go much afield, with all their powers of observation alert by day and by night. Many of the mainly nocturnal species pursue minor activities by day, where shelter of one kind or another gives them a reasonable feeling of security.

Under the revealing light of day most small mammals, especially the rodents, are extremely watchful and timid, leading lives filled with alarms which commonly end in tragic deaths. By night they appear to have far greater confidence; yet this also is a time of imminent danger from the owls and many beasts of prey then prowling about.

That the small rodents have good cause for their timorous ways is plain when we consider the array of enemies which encompass them, including owls, herons, gulls, bears, foxes, bobcats, weasels and their cousins, with snakes, and on occasion fishes, which take endless toll from their numbers. Fortunately for them, these small folk live wholly in the present and quickly forget the shadow of death cast by the passage of a hawk or the skulking form of a four-footed enemy.

COUNTLESS BEASTS THAT ROAM THE NIGHT

By day the squirrels, chipmunks, woodchucks, and spermophiles are abroad and unite with the birds to lend an air of pleasant animation to forest and plain. With the falling shades of night, near the abodes of mankind as well as in the remote wilderness, everywhere a countless multitude of small beasts come forth and form a little, bright-eyed furry world, clad in delicate shades of gray and brown and characterized by remarkable grace and agility.

These small folk of the night swarm out from snug nests hidden in burrows in the earth, in crevices among the rocks, in hollow trees, under logs or other cover, and even from the shelter afforded by buildings. In number and variety of forms they far exceed anything seen by day. The air is filled with the flitting forms of bats, while among the trees or on the ground, varying with the locality, are multitudes of rabbits, flying-squirrels, rats and mice of many kinds, lemmings, pocket-mice, kangaroo-rats, pocket-gophers, shrews, and even moles.

This abundance of night life brings forth the prowling powers of darkness in the form of velvet-winged owls, weasels, skunks, minks, martens, and other carnivores, which by scent and by keen vision find abundant harvest. The small carnivores, in turn, are subject to the predatory law of might and are at times hunted by the larger carnivores, as the great-horned owls, the wolves, foxes, fishers, bobcats, and mountain-lions.

To most people the majority of small rodents are classed as “rats” or “mice” and are viewed with the prejudice born of long familiarity with those omnipresent pests, the house rats and mice. The small beasts of field and forest are commonly of remotest kinship to these repulsive household parasites and are of entirely different lineage, having nothing in common but their size.

ANIMAL INTELLIGENCE AKIN TO MAN’S

When viewed with unbiased attention, these little animals of the wilds are certain to charm the observer either by their beauty and grace or by their varied and interesting habits. No one can long study mammals, large or small, without observing many traits of intelligence so akin to his own that they awaken feelings of friendly fellowship.

The modes of life of small mammals are much more varied than those of the larger species. At times radical differences in habits may be noted among different individuals of the same species, as instanced by the wood-rats of Santa Margarita Island, some of which live in burrows dug by themselves in the ground and others in nests built of sticks in the tops of mangroves rising amid the waters of a lagoon.

An even more extraordinary variation is shown among the heavy-bodied meadow-mice of the genus _Phenacomys_, most of which live in underground burrows; but one member of the group in Oregon builds its nests in the tops of tall conifers, sometimes at an altitude of 80 feet, and rarely or never descends to the ground.

PEEPS INTO FUR-FOLK HOMES

The homes of small mammals vary greatly. The species living in underground burrows usually excavate an oval chamber which is filled with fine vegetable material to form a snug retreat. The muskrat places a conical lodge on the border of a marshy stream or lake. The wood-rat lives in an underground burrow, in a nest of sticks and trash heaped above the ground or in a stick nest placed among the branches of low trees. Harvest mice build a little hollow ball of grass blades, lined with finer material, among the branches of bushes several feet above the ground. White-footed mice may lodge in a knot-hole 50 feet or more above ground in the trunk of a tree.

As a rule, small mammals are of inconspicuous colors which harmonize so well with their surroundings that when not in motion, especially if lying close to the ground, they are difficult to distinguish. Exceptions to this rule are obvious in the case of jack-rabbits when standing on bare plains, or other mammals which are apart from the usual partly concealing growth of vegetation or other surroundings.

In contrast to the protective coloration are certain markings, like the cottony white underside of the tail of the cottontail rabbit, which renders the flight of this animal conspicuous in the gloomiest shades of the forest, or even on the approach of night, when it is impossible to distinguish the animal itself. The white underside of the tail of the antelope chipmunk is another well-defined instance of this kind.

NEW COATS FOR BOREAS’ COURT

The most marked of all examples of “directive” coloration among the small mammals appears to be that of certain white-sided jack-rabbits, in which the white areas on the sides and rump are drawn up and down as the animal runs across the plains, giving a flashing effect, which attracts attention to them exactly as does the white rump-patch of the antelope.

In the northern part of the continent, where snow lies for many months, several species of hares are dusky or buffy gray in summer and change to a pure white coat in winter. This change is of enormous protective value to these animals. In Greenland, where the summer is short and snow exists throughout the year, the highest northern representative of the hares remains permanently white, while near the southern border of snow in the United States the varying hares and white-tailed jack-rabbits, which become pure white in the northern parts of their range, make only a partial change.

Weasels are the only carnivores which change from the brown of summer to a white winter coat. Owing to their small size and the need for activity in the snowy northern regions, where they would be peculiarly susceptible to danger from birds of prey and larger predatory animals, their protective white coats serve them well.

It was formerly considered that the change of mammals from the brown of summer to the white winter coat in the fall, and from the white to the brown in spring, was due to a change in the color of the hairs, but it is now known that it is entirely due to molt. The time of these changes depends on the season, and this varies several weeks, according to whether the fall or spring is early or late.

The general shades of mammals are of delicate tints, and the spots, stripes, and other markings, as in the case of chipmunks and the little spotted skunk, are often of great beauty.

ANIMALS THAT HAVE TO SING

Small mammals vary greatly in their vocal powers, but the changes in intonation and character of the notes and calls indicate plainly that they are used to convey a variety of meanings.

Some are practically voiceless, as in the case of rabbits and hares, except when in an extremity of fear they utter loud shrieks of terror. Squirrels, prairie-dogs, and some other small mammals bark and chatter, while mice and bats have a variety of curious squeaking notes. Marmots and ground-squirrels have chattering notes and sharp, whistling calls.

In addition, some of the squirrels and many mice are known to have continuous series of notes which are as evidently songs as the utterances of birds. Some of these notes, as in the case of singing mice, have a remarkably musical character, similar to the warblings of canaries. Various unrelated species of mice have been observed singing, and a closer study of the life habits of these small animals may develop the fact that all are songsters to some degree.

House rats and mice have, undoubtedly, been parasitic about the haunts of man from early times. From Asia they have accompanied him through his advance in civilization. With the growth of commerce they have traveled around the world, becoming transplanted to all lands and thriving in all climates. In various parts of America they have not only become pests about human habitations, but where climatic conditions were favorable have reverted to the wild state and are competing with the native species in the fields.

Of all the small mammals none have become modified to such an extent as the bats. As a group these mammals are of world-wide distribution except in the inhospitable polar regions. They are true mammals and present an extraordinary variation in size, from tiny little creatures, almost as small and fragile as butterflies, to the huge fruit-bats, with a spread of wings like that of a wild goose.

BATS WITH BULLDOG FACES

The heads of bats are strangely sculptured, some being smoothly contoured and shaped like those of little foxes; others appear like miniature bulldogs; and still others have curious cartilaginous nose-leaves upright on the muzzle. Some have the entire face molded into a hideous mask repulsive to look upon.

Their habits are equally varied to meet special conditions: Some are eaters of fruit alone; others feed solely upon insects, while others bite other mammals, including man, for the purpose of drinking the oozing blood, upon which they subsist. All are nocturnal, but some appear late in the afternoon, before the sun sets; most species, however, wait until the shades of night have covered the earth.

Throughout the world the majority of the species of bats feed upon insects, but there are many fruit-eaters. The teeming insects and plant life of the tropics afford a never-failing food supply, and the center of abundance of these animals is found there. In some localities between twenty and thirty kinds of bats exist, with such vast numbers of individuals that the bat population far outnumbers all other kinds of mammals combined.

ANIMALS THAT PUT THEMSELVES IN COLD STORAGE

In the northern parts of the Old and New Worlds many mammals, including bears, marmots, prairie-dogs, ground-squirrels, and jumping mice, pass a large part of the winter months in a lethargic sleep called hibernation. While hibernating these animals have extremely slow and slight heart action and their bodily temperature falls far below the normal of their active periods. During the most profound hibernation an animal may be awakened if brought into a warm temperature, but when again put into the cold at once returns to sleep.

Preparatory to this sleep, during the summer and in the autumn, the hibernating mammals become exceedingly fat.

It has long been generally accepted that the fat thus accumulated was for the purpose of being gradually absorbed to nourish the animals during their long fast. As a matter of fact, during this period the bodily functions appear to be practically suspended and the animals may be said to be in cold storage. This is evident from the fact that observations have been made of ground-squirrels, and even bears, emerging in spring, after their long winter sleep, practically as fat as when they retired in fall. Hibernating animals become extremely active as soon as they come out in spring and quickly lose the fat which should be of special service to them, owing to the temporary shortage of food they experience at this season.

Most hibernating species do not retire for the winter until cold weather is at hand, in September or October, at times remaining out until after the first snow has fallen. The animals which retire latest, like chipmunks and prairie-dogs, sometimes appear temporarily during certain warm periods in winter.

Recent observations have established the fact that the adults of both sexes of the Richardson ground-squirrel living in the Northwestern States and adjacent parts of Canada become excessively fat by the first of July, and before the first of August practically disappear for the season, not appearing again until they emerge the following March or April. The retirement of these squirrels for a part of the summer is a case of imperfect estivation, as it is termed, followed by complete hibernation. The young of the year enter hibernation at a considerably later date.

DEFENSIVE AND OFFENSIVE ANIMAL ALLIANCES

A great number of both large and small mammals live solitary lives except for brief periods during the mating season or the association of the young with the mother. Some species, however, like the wolves and coyotes, may mate permanently and show great mutual affection and constancy. Many species have well-developed social instincts, which appear in some cases to combine two purposes, self-defense and the desire for companionship.

Herds of large herbivorous mammals, such as musk-oxen and buffalo, frequently present a solid array of bristling horns to the attacking wolves, and thus protect the weaker members of the herd and give an example of the usefulness to them of the social instinct. Wolves and some other predatory animals hunt in couples or in packs and succeed in pulling down prey which singly they could not successfully attack.

Prairie-dogs living in colonies have the advantage of community intercourse as well as added safety through the chance that some member of the colony will espy an approaching enemy and by its warning cry allow a safe retreat. In other cases, such as the flying-squirrels, which gather in considerable numbers in hollow trees or other shelter, and the bats, which gather in caves, the congregation appears to be purely from a desire for close companionship.

=THE ANTELOPE JACK RABBIT= (=Lepus alleni= and its relatives)

(_For illustration, see page 506_)

The antelope, or Allen, jack rabbit is one of the most picturesque of American mammals. It is larger than the common western jack rabbit and is strongly characterized by enormous ears, long, slender legs, short tail, and contrasting colors. It is a member of the white-sided group of jack rabbits, which are distinguished by the extension of the white of the underparts well up on the sides of the body.

This group is represented in limited areas on our southern border by two species. One of these, the Gailliard jack rabbit (_Lepus gailliardi_), occurs on the grassy plains of extreme southwestern New Mexico and is succeeded by other white-sided species southward across the Mexican tableland and through interior Oaxaca to the Pacific coast, on the Isthmus of Tehuantepec. The other species, the antelope jack rabbit, occupies a considerable area in southwestern Arizona, and with its geographic races ranges southward through the coastal plains of Sonora and Sinaloa to northern Tepic.

All jack rabbits are more or less closely related to the Old World hares, the term “rabbit” having been so generally misapplied to them by the early settlers in the western United States that the name is now fixed by current usage. In Mexico and among the Mexicans of our southwestern border the proper distinction is made and the jack rabbit is termed _liebre_, or hare, and cottontail is called _conejo_, or rabbit.

The white-sided species are more widely differentiated from their Old World relatives than the other jack rabbits and are the southernmost representatives of the true hares in America, reaching their limit in the tropics a little beyond the Isthmus of Tehuantepec.

The extension of the white on the sides of these species assists in producing one of the most extraordinary examples of directive coloration known among mammals. I had the pleasure of discovering this one day in May, 1895, when hunting on horseback over the grassy plain bordering the Pacific coast of the Isthmus of Tehuantepec. As I rode slowly along, a big jack rabbit hopped deliberately from its form in the grass a few yards away, and by the contraction of a special set of muscles along the back drew the dark-colored dorsal area forward and together so that it formed only a narrow band on the middle of the back, with a corresponding extension of the white area on the rump and sides until, as the animal moved diagonally away, it looked almost entirely white.

At a distance of fifty or sixty yards it came to a stop, and expanded and contracted the dark dorsal area, thus producing a “flashing” effect with the changing area of white on the sides and rump. This solved the riddle of the mirror-like white flashes I had often seen as jack rabbits on the tableland had dashed away in the brilliant sunshine. The same habit of “flashing” the white was afterwards observed in the species of southwestern New Mexico and southwestern Arizona, demonstrating the appropriateness of the name, “antelope jack rabbit,” given them by the ranchmen.

Formerly the antelope jack rabbit of Arizona was common on the plains about Tucson, where many were shot for rifle practice. They are now comparatively scarce in that district, and are never so excessively abundant as the common species of the West now and then becomes. They have an extraordinary appearance as, with their great ears erect, they stand poised on their long, thin legs. When alarmed, they leap away with amazing celerity in long, high bounds. They are usually much more shy and alert than the common jack rabbits and at times are far more difficult to stalk than antelope. A peculiarly appropriate setting to this remarkable species is found in the strange and wonderful growth of giant cactuses, yuccas, creosote bushes, fouquerias, palo verde, and other desert vegetation of the plains in Arizona and Sonora.

Like other hares, the antelope jack rabbits occupy forms under bushes or in the shelter of little patches of coarse vegetation. The only exception to this rule I have seen was west of the city of Guadalajara, on the Mexican tableland. There one summer day, in the midst of a lovely open valley covered with short, velvety green grass and dotted with scattered acacia bushes, a caracara eagle suddenly swooped down upon a young white-sided jack rabbit. In mortal terror the little beast dashed away at great speed, the caracara casting at it repeatedly from a height of fifteen or twenty feet and each time striking the ground just behind. The young animal ran not less than five hundred yards, straight for a little bush on a small bank, where it vanished as by magic.

The caracara was close behind and, alighting, ran round and round the trunk of the bush, craning its neck and apparently as surprised as myself at this sudden disappearance. Riding over to investigate, I found, partly concealed by coarse grass, the entrance of a burrow large enough to admit an adult jack rabbit. It extended almost horizontally into the bank for about eighteen inches, and then, turning abruptly to the left, ended in a rounded chamber some fifteen inches in diameter, in which the young jack rabbit lay snugly ensconced. It appeared altogether probable that this burrow had been made by the old jack rabbit as a shelter for her young, one of which in its extreme need had again sought asylum there.

White-sided jack rabbits are frequently found in pairs, occupying forms in close proximity to one another. More rarely several may be found in a small area. When driven from the forms, they often run in a wide circle, and in the course of half an hour or more may be detected returning slyly and watchfully from a direction nearly opposite to that in which they departed.

THE CALIFORNIA JACK RABBIT

(=Lepus californicus= and its subspecies)

(_For illustration, see page 507_)

The common hares, or gray-sided “jack rabbits” of the Western States, are among our best known and most interesting mammals. They are characterized by long, thin necks, long ears tipped with black, long legs, grayish sides differing but little from the color of the back, and a rather long tail, black on its upper side and dingy gray below.

They are abundant and generally distributed over a vast and mainly treeless area in middle North America extending from western Missouri and eastern Texas to the Pacific coast, and from the border of South Dakota and the Columbia River Valley of Washington south over the tableland of Mexico and throughout the peninsula of Lower California. Within this region they range from sea level up to an altitude of over 9,000 feet. In the North they experience severe winters with much snow, but never show any winter whitening of their furry coat, as do more northern hares.

The gray-sided hares over all this extended range belong to a single species, typified by the California jack rabbit. The area thus occupied includes many different climatic and other physical conditions, from the sweeping grassy plains of Kansas to the juniper and pine dotted plateaus of the Rocky Mountain region, the foggy coast of California, the hot cactus-grown deserts of the Southwest, and the cool elevations of the Mexican tableland.