[Illustration: BROWN LEMMING
_Lemmus alascensis_]
In general they prefer comparatively dry situations, if there is
sufficient moisture to produce the needed vegetation, but some species
inhabit swamps and even salt and fresh water marshes. Although as
a rule not very numerous, at times they are very abundant and make
well-worn trails through the small vegetation in their haunts. They are
active throughout the year, and in the North, like some other mice,
burrow through the winter snows along the surface of the ground in
search of food.
So far as man is concerned, most of the harvest mice are among the
least offensive of mammals. There are exceptions, however, and,
although they rarely approach habitations and as a rule take but slight
toll from grain fields and meadows, yet in some areas they become so
numerous as to do considerable damage.
Their food includes a great variety of seeds, small fruits and
succulent matter mainly from wild plants of no economic value. They lay
up stores of seeds in their nests and in little special storage places
for severe or inclement weather.
Some of the species dig burrows in the ground where their nests are
hidden. Most of them, however, build globular nests of grass and other
vegetable matter several inches in diameter in dense grass close to the
ground, or up in the midst of rank growths of weeds, or even as high as
eight or ten feet from the ground in bushes and low trees.
Sometimes they take possession of convenient sites already provided,
such as old woodpecker holes, cavities in fence posts, knot holes,
and deserted birds’ nests, including the nests of the cactus wren and
orchard oriole, which they remodel to suit themselves. Their nests are
lined with fine downy material such as the pappus of the milkweed or
the cattail flag, and have from one to three small openings usually
located on the underside. In these neat homes they have several litters
of from one to seven young each year.
Some of their bush nests three or four feet from the ground were found
when I was hunting on El Mirador coffee plantation in Vera Cruz. Often
on approaching them, the single occupant would dive headlong into the
grassy cover below and disappear. But sometimes when disturbed they
would come out and run about through the tops of the bushes, leaping
from branch to branch with all the agility and graceful abandon of
pigmy squirrels. Several times they were seen to stop and sit crosswise
on the branches with their tails hanging straight down. When they move
about among the branches they sometimes coil the tail around the twig
as an opossum might, to give them a more certain hold.
While harvest mice may be seen at their nests by day, they are mainly
crepuscular and nocturnal, and so retiring in habits that their
presence may be entirely overlooked unless special search is made to
locate them. Where found their pretty ways well repay the observer who
has the patience to spend a little time with them.
=THE GRASSHOPPER MOUSE= (=Onychomys leucogaster= and its
relatives)
(_For illustration, see page 527_)
The grasshopper mice are notable for the delicate coloring and velvety
quality of their fur. While closely resembling some of the white-footed
mice, they may readily be distinguished from them by more robust form,
short, thick tail, and the character of the fur.
Only two species, each with numerous geographic races, are known and
both are peculiar to North America. Characteristic animals of the
arid and semi-arid treeless plains, plateaus, and foothills of the
West, their known range extends from Minnesota and Kansas west to
the Cascades and to the Pacific coast of southern California, and in
the North, from the plains of the Saskatchewan southward to San Luis
Potosi, on the tableland of Mexico.
Some races live on the grassy plains west of the Mississippi, but
the majority prefer the looser soil and sandy areas of the more arid
Great Basin and the even more desert Southwest, where the vegetation
is characterized by a scattered growth of woody plants, including many
species of cactuses, yuccas, agaves, sagebrush, greasewood, mesquites,
acacias, and other picturesque types.
Like other small mammals of the open plains, the grasshopper mice live
in burrows. When opportunity offers they evade the labor of digging
these for themselves by occupying the deserted holes of mice, kangaroo
rats, ground squirrels, prairie dogs, badgers, and other animals. In
these retreats they have nests of soft vegetable matter and each season
bring forth several litters containing from two to six young.
They are active throughout the year, but nothing appears to be known as
to the kind and amount of stores they lay up for winter use. As many
live far enough north to experience a long period of cold, with snow
covering the earth, there is little doubt that they exercise the same
provision in providing stores to meet the need as do many other small
mammals.
Many species of mice eat insects or meat and even on occasion devour
one of their own kind. The grasshopper mice go far beyond this and are
often not only as fierce flesh eaters as real carnivores, but make
their diet, at least during the summer season, mainly of insects and
other small invertebrates. Their bill of fare includes a miscellaneous
assortment of several species of mice, including their own kind caught
in traps, small dead birds, lizards, frogs, cutworms, scorpions, mole
crickets, ordinary crickets, grasshoppers, moths, flies, and beetles,
including the “potato bug.”
In addition they eat many kinds of seeds, fruit, and other vegetable
matter. Where obtainable, grasshoppers are one of their favorite foods,
and from this they receive their common name. In Colorado, from their
fondness for scorpions, they are sometimes called “scorpion mice.”
Vernon Bailey’s observations of a grasshopper mouse he had in captivity
are illuminating as to their habits, and indicate that their presence
in numbers about cultivated land must be of distinct economic value.
When undisturbed and well fed the captive was entirely nocturnal,
sleeping all day and becoming very active at night. While usually
quiet, sometimes jumping with all his force he tried furiously to
escape from his small prison box. His favorite food consisted of
crickets, grasshoppers ranking next. Among other things he ate were a
black beetle, ladybirds, a potato beetle, spiders, bugs, and dragon
flies.
In feeding he sat upright on his haunches and held the insects in his
front paws, eating them head first. Large grasshoppers, their tails
resting on the ground, were held head up by a paw on each shoulder. A
grasshopper would sometimes kick so vigorously as to tip the mouse off
its balance, but was never relinquished until decapitated.
The mouse promptly killed and ate a small frog placed in his box and
was expert at catching flies. He ate many kinds of insects, including a
live wasp, but appeared terror-stricken if a few ants were put in with
him. When a dozen or more crickets and grasshoppers were put into his
box at the same time he at once proceeded to bite off all their heads
before beginning to feast upon them.
A dead white-footed mouse was dropped in and “he pounced upon it like a
cat, caught it by the side of the head near the ear, and began biting
it with all the ferocity of a coon dog.” The bones could be heard
cracking and after the little beast appeared satisfied that his prey
was really dead he ceased worrying it and an examination showed that
he had bitten through its skull deep into the brain. Afterward he tore
off and ate fragments of flesh from its head, neck, and shoulders. The
ferocious certainty with which he seized the white-footed mouse by the
head and bit through its skull indicated that in relation to small
mammals he, probably like all his kind, had the predatory instincts and
habits of the carnivores.
One morning he ate 12 crickets and a spider in seven minutes and
during a single day devoured 53 insects--2 beetles, 8 grasshoppers, 28
crickets, and 15 flies--and appeared ready to take more.
Oddly enough, this grasshopper mouse, so fierce toward small game,
never offered to bite when captured or when handled freely, but
continued throughout his captivity to have the same friendly confidence
in his captor. Others caught in various parts of their range have shown
the same characteristics.
At night, especially early in the evening, grasshopper mice utter a
fine shrill whistling call note. This habit appears peculiar to them
among all the mice and may be likened to that of many of the large
beasts of prey in uttering their hunting call as they sally forth for
the night’s foray.
=THE WHITE-FOOTED MOUSE= (=Peromyscus leucopus= and its
relatives)
(_For illustration, see page 530_)
Few of our smaller wild mammals are so generally known as the
white-footed mice. Usually a little larger and proportionately shorter
bodied than the house mice, they may at once be distinguished from them
by the contrast between the delicate shades of fawn color, brown, or
gray of the upper parts of the body, and the snowy white feet and under
parts. Like other members of the genus, they have cheek pouches inside
the mouth for gathering and carrying food to their stores.
Their exceedingly quick and graceful movements and their beauty of form
and color would make them generally attractive were it not for the
prejudice against all their kind resulting from the offensive ways of
the house mouse.
Mice of the genus Peromyscus, to which the white-footed mice belong,
are peculiar to North and South America and include more species
and geographic races than any other American genus of mammals. The
white-footed mice are limited to North America. Readily responsive to
the influences of environment, they have developed numerous species and
a large number of geographic races.
These are spread over most of the continent from the northern limit of
trees to the tropical shores of Yucatan. One form has the distinction
of living up to an altitude of from 15,000 to 16,000 feet on Mount
Orizaba, Mexico, where I found its tracks in the volcanic ashes at the
extreme limit of vegetation. This is the highest record for any North
American mammal.
White-footed mice are active throughout the year and thrive in every
variety of situation. In winter from the Northern States to the Arctic
circle the snowshoer traversing the forest will note their lace-work
patterns of tiny tracks leading across the snow from log to log or
tree to tree. At sunrise on the southwestern deserts their tracks made
during the night often form a fine network in the dust, but disappear
with the first breath of the morning breeze.
They not only live everywhere in the wilderness, but are prompt to
swarm about camps and other habitations, where they make free with the
food supplies. Few frequenters of forest camps in the Northern States
and Canada have failed to see the bright eyes of these pretty little
animals peering at them from some crevice, or the mice scurrying along
the log wall like little squirrels.
[Illustration: FIELD, or MEADOW, MOUSE
_Microtus pennsylvanicus_]
[Illustration: PINE MOUSE
_Pitymys pinetorum_]
They are industrious workers and once in a cabin quickly locate some
cozy nook in a box or other secluded place to construct a warm nest
of any soft fibrous vegetable material available. This completed,
they set busily at work nights to raid the food supply of the owner and
hide it in suitable storage places, such as a crevice among boxes, an
old shoe or a pocket in a garment hung on the wall. Their depredations
usually cause so much exasperation that the camper overlooks the grace
and beauty of his visitors and makes every effort to destroy them. If
the occupants of such camps would keep their supplies in mouse-proof
containers and would then feed their woodland friends, they would find
them quickly responsive and most attractive guests.
[Illustration: RED-BACKED MOUSE
_Evotomys gapperi_]
[Illustration: RUFOUS TREE MOUSE
_Phenacomys longicaudus_]
In their native haunts these mice have habits varying with varying
conditions. On brushy plains they burrow in the ground, while in the
woods they sometimes burrow under rocks, stumps, and logs, or live in
hollows in stumps and trees. As nimble in climbing as squirrels, many
live in hollow trees sometimes more than fifty feet above the ground.
That our inability to see at night prevents more than an occasional
glimpse at the doings of the small animals which often swarm all about
us was impressed on me at one of my camps in the desert of Lower
California. My blankets were spread under a small leafless tree growing
near the base of a rocky ledge, in the crevices of which many relatives
of the white-footed mice were living. The first morning in camp I awoke
as the sky began to pale and color with the approach of day. The dry
branches of the tree a few feet overhead became sharply silhouetted
against the sky, revealing several of the mice running up and down
them and leaping from twig to twig with all the active grace of tiny
squirrels.
The mice appeared to be racing about in pure playful enjoyment of the
exercise, and when the light had increased sufficiently to render
objects on the ground distinct they suddenly ran down the tree trunk
and vanished in a crevice in the rocks. This game was repeated on
several succeeding mornings and is no doubt commonly indulged in where
conditions are favorable.
White-footed mice feed mainly on many kinds of seeds and nuts and vary
this diet with snails, insects, and sometimes with the flesh of dead
birds or other mice. As they do not hibernate they lay up abundant
stores of grain and seeds of many kinds in addition to a variety of
nuts, as acorns, beech nuts, pine nuts, maple seeds, and others,
according to the locality. The stores are hidden in hollows in logs,
stumps, trees, or in the ground. When in captivity they have shown
themselves expert in catching flies, sometimes capturing them with
their teeth and again with their front paws used with all the dexterity
of little hands.
Several litters of young containing from three to seven each are
born, the first usually appearing in spring and the last in fall. The
young are blind and helpless at birth, and in this condition cling so
tenaciously to the mother’s teats that when she is frightened from the
nest they are often carried off attached to her.
Some individuals at least of the white-footed mice, like others of the
genus Peromyscus, are known to have a prolonged and musical song. It
is a fine warbling ditty, a little like the song of a canary. A number
of good observers have recorded these performances, but they appear to
be so infrequent that most people with woodland experience have never
heard them.
The lives of these mice are passed in constant fear of a host of
enemies. Hawks and owls, bluejays, and shrikes in the bird world are
ever on the alert to capture them, while skunks, weasels, minks, foxes,
and snakes persistently seek them in their retreats.
=THE BEACH MOUSE= (=Peromyscus polionotus niveiventris= and
its relatives)
(_For illustration, see page 530_)
The beach mouse is a beautiful, velvety-furred little creature about
the size of a house mouse and one of the smallest species of the
genus Peromyscus. Its back is colored with delicate shades of pale
vinaceous-buffy and its underparts, including the feet, are snowy white.
The species _Peromyscus polionotus_, of which the beach mouse is one
of several geographic races, or subspecies, occupies a comparatively
restricted range in the lowland region of Alabama and Georgia and
thence through a large part of Florida.
It presents an unusually convincing illustration of the influence of
changing environment upon the physical characters of animals. Among
the cotton fields of Alabama and Georgia _Peromyscus polionotus_ is
rather dark grayish brown, but on the lighter-colored soil of Florida
the color responds and becomes paler in perfect correspondence with
the change in soil until the white sand-dunes and beaches of the coast
are reached. There, in strong contrast with the color of the northern
members of the species, it is so modified that the pale representatives
of this area are recognized under the name _niveiventris_, as a
geographic race, or subspecies.
Changes in environment affect both great and small mammals in a variety
of ways, sometimes in shades of color, sometimes in relative size,
and sometimes in proportions. Exceptions to the rule are to be found,
however, and some species of mammals have a wide range under a great
variety of conditions, with scarcely an appreciable sign of variation.
The beach mouse is abundant on the sand-dunes and beaches of peninsular
Florida, especially from Palm Beach to Mosquito Inlet, wherever there
is a growth of sea oats (_Uniola_), which appears to be its principal
food plant. It is a nocturnal animal and its nightly activities may be
read, early in the morning, from the multitude of tiny tracks which
lead in all directions and often form a network on the sand. A single
track sometimes extends for a hundred yards or more from a burrow, and
with all its windings may aggregate several hundred yards of travel,
showing the activity of this small worker during many hours.
Tracks are most plentiful immediately about growths of sea oats,
patches of saw palmetto, or scrubby bushes. The homes of these mice
are usually in short burrows sheltered by growing vegetation or under
fallen palm fronds.
As in the case of many of our mammals, we have scanty information
concerning the life of these attractive little animals, and it is
suggested that here lies a pleasant subject for investigation by some
nature lover wintering in Florida.
=THE BIG-EARED ROCK MOUSE= (=Peromyscus truei= and its
relatives)
(_For illustration, see page 531_)
The numerous species of mice of the genus Peromyscus in North
America include a great variety of little beasts, many of which are
distinguished by beauty of form and color. One of the most striking and
picturesque individualities among these is found in the big-eared rock
mouse, which is characterized by its great ears, a thick, soft coat
of buffy brown fur, and a long, well-haired tail. In size it exceeds
the common house mouse and even the white-footed mice which share its
haunts.
This rock mouse is indigenous to the mountainous regions of the West,
from Colorado and New Mexico to the Pacific and south to the Cape
Region of Lower California, and down the Sierra Madre of Mexico to
Oaxaca. Within this area it divides into several not very strongly
marked geographic races.
As implied by its common name, it is a characteristic dweller among
cliffs and ledges along the mountain slopes or rocky canyon walls,
where it occupies the many crevices and little caves. In California it
ranges from near sea-level up on the mountains to above 10,000 feet
altitude. Although showing a distinct preference for rocky places,
when available, some races of this mouse adapt themselves to other
conditions and may be found on brush-grown flats, where they live in
brush heaps, old wood-rat nests, and similar shelter.
That they make their homes in places other than cliffs in New Mexico
was evidenced by a thick, soft nest made almost entirely of wool, found
in a hollow juniper. They have several litters of from two to six young
each year, the breeding period extending from spring to fall.
In Arizona and New Mexico I found the rock mouse most numerous in the
belt of junipers and pinyons and in the adjacent yellow-pine forest.
The crevices of cliffs about the Moki and Zuni Indian pueblos and in
all the rocky wilderness of that region, including the Grand Canyon,
are abundantly populated with them.
They search every nook about their haunts and often visit cabins or
temporary camps for food, but do not usually take up their abode in
them as do the white-footed mice. When foraging their movements are
quick, and when startled they make surprisingly long leaps. Like others
of their kind, they eat a great variety of seeds and small nuts,
quantities of which they lay up in winter stores. Pinyon nuts, and
especially juniper seeds, are their favorite food.
While of nocturnal habits, rock mice at times wander forth in sheltered
spots by day, and on the few occasions I have seen them I have been
delighted with their grace and beauty, their great ears and prominent
shining black eyes lending them an attractive air of alert intelligence.
Throughout their lives they are in deadly peril from predatory foes.
Hawks and owls glide shadowlike along the faces of their rocky homes
ready to pick them up whenever they venture into open view, while
bobcats, skunks, and weasels prowl about by night hunting their furry
victims.
=THE BROWN RAT= (=Rattus norvegicus= and its relatives)
(_For illustration, see page 531_)
It is safe to assume that few readers need an introduction to that
world-wide pest variously known as the brown rat, house rat, wharf rat,
or Norway rat. Two European relatives, the black rat and the roof rat,
preceded the brown rat to the New World and became widely distributed.
They resemble the brown rat, but are much smaller and are soon killed,
driven away, or reduced to a secondary status by their larger and
fiercer cousin, which averages about sixteen inches in length, although
large individuals attain a length of more than twenty inches and a
weight of more than two pounds. The black rat has nearly disappeared
from most of its former haunts in the United States and the roof rat is
mainly restricted to southern localities with a mild climate.
Neither the brown, black, nor roof rat has any near relatives among
native rats of America, and all may be distinguished from our native
animals by their coarser hair and long, naked tails.
The brown rat is believed to have first invaded Europe from Asia in
1727, when hordes of them swam the Volga River, and about the same year
it arrived in England on ships from the Orient. Since then, traveling
by ships and by inland commercial routes, it has spread to nearly all
parts of the globe. In America it is now established in human abodes
throughout the length and breadth of the continents from Greenland to
Patagonia.
Wherever it goes the fierce and aggressive spirit with which it is
endowed qualifies the brown rat more than to hold its own against all
rivals, while its mental adroitness and its fecundity have largely
nullified the constant warfare being waged against it by all mankind.
Not content with infesting ships, dwellings, stores, warehouses, and
even the refrigerating rooms of cold-storage plants in many areas, it
has established itself as an extremely destructive pest in the open
fields.
[Illustration: MUSKRAT
_Fiber zibethicus_]
[Illustration: WOOD RAT
_Neotoma albigula_]
In towns it hides among stored merchandise, in the hollow walls of
buildings, in sewers and other underground passages, or, as in the
fields, in burrows which it digs in the ground. Its nests are
soft, warm masses of fibrous material which is secured by raids on
any available supply of cotton, wool, or fabrics, which they cut into
shreds for the purpose.
[Illustration: HARVEST MOUSE
_Reithrodontomys megalotis_]
[Illustration: GRASSHOPPER MOUSE
_Onychomys leucogaster_]
In these retreats it has several litters a year, averaging about ten
young, but exceptional cases of more than twenty young have been
recorded. The young begin to breed when less than six months old. The
size and number of litters increase with the food supply, and under
favorable conditions rats soon become intolerable pests.
In Jamaica and the Hawaiian Islands rats became so numerous that
sugar-cane and other plantations were at one time threatened with
complete destruction. To save the crops the mongoose was introduced,
but after checking the rats in Jamaica these curious little mammals in
turn became a pest which it appears hopeless to control.
In the Hawaiian Islands the mongoose reduced the number of rats, but
the survivors promptly took up their abodes in the tree tops, where
they now live as completely arboreal lives as squirrels, safe from
their ground-inhabiting enemy.
During a two weeks’ campaign against rats in the sewers of Paris
600,000 were killed, and on a rice plantation of about 1,200 acres in
Georgia 30,000 were destroyed in one season. In Illinois 3,435 were
killed on a farm in one month.
One of the most curious chapters in the life of this hardy beast is
now developing in the far island of South Georgia, on the border of
the Antarctic, east of Cape Horn. On this island, which has a cold
and stormy summer and nine months of rigorous winter, several whaling
stations have been established. For years great numbers of whale
carcasses have drifted ashore each season and, half rotting, half
refrigerated, have furnished a never-failing food supply for brown
rats that have landed from the ships. With such abundant food they are
reported to have increased until they now exist there literally in
millions. They make their nests in the tussocks of grass and peat and
swarm along well-marked trails they have made on the mountain sides.
In the trenches along the battle front in France they have become
extremely abundant and troublesome, and in England have multiplied
until the Board of Agriculture is recommending efforts to destroy them
as a menace to the public welfare through their waste of food supplies.
On farms, in addition to destroying growing and stored crops, they kill
great numbers of young chickens, turkeys, and other poultry, and create
havoc with such ground-frequenting game as pheasants. At all times
brown rats are more or less carnivorous, and when several are confined
in a cage the stronger will soon kill and devour the weaker.
In city department stores and large hotels they often cause thousands
of dollars damage yearly in single establishments. An English
organization for their destruction estimated in 1908 that, outside the
towns and shipping, in Great Britain and Ireland they caused annual
losses of about $73,000,000.
When there is a sudden diminution in the food supply, an abundance
of which has caused a great increase in the rat population, the rats
migrate into other districts, sometimes in enormous numbers. These
migrations usually occur at night, and many are matters of history in
Europe and in the United States.
A witness of one of these migrations in Illinois in 1903 reported
that one moonlight night as he was passing along the roads he heard a
rustling in a field near by and soon saw crossing the road in front of
him a multitude of rats extending as far as he could see. The following
year the invaders became a plague in that district. At times of food
scarcity rats become extremely bold and aggressive. Without hesitation
they swim streams encountered in their wanderings and at times will
even attack man.
Owing to their great numbers, universal distribution, and
destructiveness, brown rats are the worst mammal pest known to
mankind. Through their habit of living in sewers, among the offal
of slaughter-houses, and in garbage heaps, from which they invade
dwellings and storehouses, they pollute and spoil even more foodstuffs
than they eat.
In addition, they are known carriers of some of the worst and most
dreaded diseases, as bubonic plague, trichinosis, and septic pneumonia;
while there is little doubt that they spread scarlet fever, typhoid,
diphtheria, and other contagious maladies. Bubonic plague is mainly
dependent upon rats for its dissemination and has been carried by
them to more than fifty countries, including the United States. In
India more than two million people have died in one year from this
rat-conveyed disease.
Although rats are abhorred by man, yet they have been for ages so
closely associated with most of his activities that they have long
had their place in Old World literature. Among other instances, many
readers will recall Victor Hugo’s gruesome account of Jean Valjean’s
fight with the rats in the sewers of Paris. In England and on the
continent rat catching has been a regular trade and dogs have been
specially bred for use in their pursuit.
Rats are loathsome vermin which civilized man should eliminate with the
other evils of his semi-barbaric days which he is leaving behind. One
might still wish that in many places a modern “Pied Piper of Hamelin”
would appear and rid the people of these pests. This is not necessary,
however, if the public will cease to take their presence as a matter
of course. Their exclusion from buildings and destruction are merely
matters of good housekeeping, both personal and communal.
Rats can be banished by removing or destroying trash heaps and similar
harboring places and by the simple expedient of rat-proofing buildings,
especially dwellings, granaries, warehouses, and other places where
food supplies are stored.
These precautionary measures should be supplemented by trapping
or poisoning in open places. Campaigns of this kind can be fully
successful only when engaged in by the community at large. The returns
from the investment for such a purpose will be large, not only in the
vast money values of property saved, but in the reduction of the death
rate and in the great improvement of the public health.