Feb. 9, 1907.] 
FOREST AND STREAM. 
213 
* 
!• 
1 
f 
1 
, 
i 
i 
I 
1 
The Threatening Meadow Mouse. 
BY D. E. LANTZ, ASSISTANT, BIOLOGICAL SURVEY. 
Its Habits. 
Notwithstanding meadow mice are much 
alike in manner of feeding and nesting, in other 
respects marked differences in their habits have 
been observed. Some of them prefer high and 
dry ground, and others live in low, moist places. 
Some remain in forests, and others on the open 
prairies. Some, like moles, make long burrows 
under the surface of the soil, while others con¬ 
struct runways on top of the ground. Most of 
the species live where there is considerable mois¬ 
ture; and a few are almost as aquatic as the 
closely allied muskrat. Aquatic habits are the 
rule more especially with the larger kinds. Some 
of the species emit a strong odor not unlike 
that of the muskrat. 
The nests of meadow mice are composed 
mostly of compact bunches or balls of grass 
blades, placed in depressions in the ground or 
shallow burrows; or, if the ground is very moist, 
supported on grass stems five or six inches above 
the wet surface. They are so light in structure 
that after a storm a day’s sunshine will dry 
them out; and yet they are so warm that the 
animals pass the coldest season snugly housed 
in them under the snow. In these nests the 
hairless young are produced and nursed. When 
the mother is suddenly disturbed, she slips away 
from the nest, often carrying the young mice at¬ 
tached to her mammae, to return promptly when 
the premises are again clear. 
The breeding season of meadow mice extends 
over most of the year, except midwinter of the 
coldest latitudes. The number of litters pro¬ 
duced depends largely upon the character and 
length of the winter. It is certain, too, that the 
number of young at a birth varies with the 
character of the season. A few species produce 
habitually from two to four at a litter, but other 
species bring forth eight to eleven. Most of the 
species have four to six litters in a year. Pre¬ 
cise knowledge on this point is wanting, and the 
period of gestation can only be guessed at as 
about twenty-one days. Members of the Bio¬ 
logical Survey record the finding of pregnant fe¬ 
males or young in the nest during every month 
from March to December. 
The common meadow mouse ( M. pennsylvani- 
cus ) is one of the most prolific of the American 
species. If six young, the average number, are 
produced at a birth, and four litters in a season, 
and if no enemy or disease check the multipli¬ 
cation, the increase would be appallingly great. 
A single pair and its progeny would in five sea¬ 
sons amount to over 2,000,000. This calcula¬ 
tion is conservative, being based on the theory 
that the young of one season do not breed until 
the next year—an assumption that is likely to be 
incorrect; for the animals mature very quickly, 
and the young born in spring probably breed in 
the fall of the same season. If a thousand pairs 
of meadow mice survive a winter in any local¬ 
ity, it is easy to understand how, after two or 
more seasons of uninterrupted increase, they 
might become a menace to agricultural interests. 
Investigation of the food of rodents is diffi¬ 
cult because of the finely ground condition of 
the stomach contents, and usually the nature of 
the food can be determined only in a general 
way. In summer, the principal food of meadow 
mice is green vegetation and unripe seeds of 
grain and grasses. In winter, grain and bulbous 
and other roots are usually eaten, but sometimes 
the bark of various trees becomes a staple food. 
It is mainly in winter that apple orchards and 
young forest plantations suffer from the depreda- 
dations of these animals. Such attacks are not 
always due to severe weather which deprives 
them of their ordinary food, for they often occur 
during mild, open winters. The depredations 
seem to result rather from the excessive numbers 
of the animals and the consequent scarcity of 
food, which renders them so voracious that they 
are ready to devour any vegetable substance. 
Stomach examinations show that in addition 
to bark, green leaves, and seeds of grasses and 
sedges, field mice eat all kinds of bulbs, tubers, 
and roots, and occasionally animal food. The 
larger aquatic species are said to eat fish, mol- 
lusks and crayfish. When a number of these mice 
are kept in confinement, the stronger animals 
usually devour the weaker, and our field natural¬ 
ists have frequently noted that trapped field mice 
are devoured by their brethren. 
It has been calculated that each adult meadow 
mouse requires from twenty-four to thirty-six 
pounds of green vegetation per year. It is thus 
apparent that the total amount eaten by the 
hordes that ordinarily infest the meadows, 
swamps and forests of our country is incal¬ 
culable, and is a steady drain upon the resources 
of the farmer. 
Damages that they Cause. 
Meadow mice have been known to almost 
wholly destroy large nurseries of young apple 
trees. It was estimated that the losses sustained 
by nurserymen near Rochester, N. Y., during the 
winter of 1902 amounted to $100,000. The animals 
usually inflict the damage by burrowing under 
the snow and girdling the tree just at the sur¬ 
face of the ground. Some species burrow below 
ground, and, like the pocket gopher, eat the roots 
of trees, thus completing their destruction. 
In some cases older trees are attacked and 
ruined. The writer has seen many apple trees, 
eight or ten years transplanted, and four to 
six inches in diameter, completely girdled by the 
prairie meadow mouse ( M. austerus), sometimes 
to the height of a foot or more above the ground. 
Natural Enemies of Meadow Mice. 
One of the chief causes of the recent great increase 
of the smaller rodent pests is the persistent des¬ 
truction of the birds, mammals and reptiles that 
habitually prey upon them. This is true not only 
in America, but also in Great Britain and on the 
Continent, where for years game keepers and 
even farmers have destroyed foxes, weasels, 
stoats, hawks and owls whenever possible on the 
plea that they prey upon and diminish the supply 
of game in the parks and preserves. 
Among the wild mammals of the United States 
that are known to prey upon meadow mice are 
wolves, lynxes, foxes, badgers, raccoons, opos¬ 
sums, skunks, minks, weasels and shrews. The 
majority of these animals destroy mice habit¬ 
ually; and this service, together with their well 
known habit of destroying noxious insects, goes 
far to compensate for the damage they do in 
other directions. 
Among birds that feed on meadow mice are 
hawks, owls, crows, shrikes, cranes, herons and 
bitterns. Of hawks, the kites and the marsh, 
red-tailed, red-shouldered, broad-winged, rough¬ 
legged, pigeon and sparrow hawks feed upon 
them, SOTne destroying lar^e numbers of the two 
most destructive soecies (M. pennsylvanicus ) and 
(M. austerus ). Pine mice live mostly below the 
ground and are less frequently caught by birds 
of prey. 
The habit of shrikes of catching meadow mice 
is well known, and most farmers have seen these 
birds in the corn fields at husking time, as they 
hover in the air or sit poised upon a fence or 
hedge ready to pounce upon every mouse that 
escapes from the shocks. 
Crows destroy many young mice in the nests 
and sometimes kill the adults, and no doubt, in¬ 
vestigations will show that meadow mice form 
a considerable part of the diet of bitterns and 
herons. 
Owls are especially efficient as destroyers of 
field mice, and all the species whose food habits 
have been investigated by the Biological Survey 
were found to feed upon these animals. In Bul¬ 
letin No. 3 of the Survey* it is recorded that of 
39 barn-owl stomachs examined, 7 contained 
meadow mice; of 107 long-eared owl stomachs, 
59 contained them; of 101 stomachs of the short¬ 
eared owl, 52 had meadow mice; 31 out of 109 
stomachs of the barred owl, 6 out of 9 of the 
great gray owl, 4 out of 22 of the saw-whet 
owl, 18 out of 254 of the screech owl, 12 out of 
127 of the great horned owl, 10 out of 38 of the 
snowy owl, and the stomach of' the single hawk 
owl, contained meadow mice. They were mostly 
the common meadow mouse ( Microtus pennsyl¬ 
vanicus), as the birds were collected for the 
most part where this species is common. 
The examination of owls’ nests and of the 
curious pellets cast up by owls reveals much as 
to the nature of their food. Dr. Fisher has re¬ 
corded the results of the examination of many 
pellets of the barn owl, and a few of those of 
the long-eared owl, with the following result: 
Six hundred and seventy-five barn-owl pellets 
contained 1,123 skulls of the meadow mouse; 50 
pellets of the long-eared owl contained 114 mea¬ 
dow mouse skulls. This is an average of‘almost 
two to each pellet. 
Notwithstanding the unanimous testimony of 
careful students of bird life to the effect that 
almost all owls are wholly beneficial to the far¬ 
mer, few laws for the protection of these birds 
have been enacted, and a widespread prejudice 
exists against them. They are destroyed as re¬ 
lentlessly as if they were enemies instead of 
friends of the farmer. It is to be hoped that 
an enlightened public will soon come to recog¬ 
nize the good offices of the owls, and extend to 
them the protection necessary to prevent the ex¬ 
tinction of any American species. 
Next to insects, mice form the most impor¬ 
tant item in the food of snakes. Meadow mice 
are most easily obtained, but other mice, and in¬ 
deed, most of the small rodents, including ground 
squirrels, wood rats, prairie dogs, and young 
pocket gophers and rabbits, are eaten. This im¬ 
portant service of snakes in the interest of the 
farmer is not generally understood or appre¬ 
ciated, but an inherent and deeply rooted pre¬ 
judice induces thoughtless people to destroy them 
whenever possible and for no other reason than 
because they are snakes. 
The value of domestic cats and of dogs in de¬ 
stroying mice is well known, and many of these 
animals learn from experience to prefer the 
large meadow mice to the species found in houses 
and barns. Dogs that never eat the common 
mouse or rat will sometimes eat meadow mice 
greedily. The great objection to the utilization 
of cats to check the inordinate increase of field 
mice is that when cats take to roaming the field 
and forest they soon learn that song birds are 
more toothsome than mice, and turn their atten¬ 
tion largely to the pursuit of such birds. In 
thus destroying birds, cats much more than off¬ 
set their value as mouse catchers. 
Destroying Meadow Mice. 
The writer has given considerable attention to 
methods of dealing with prairie meadow mice 
(M. austerus). In December, 1903, he was called 
to Marion county, Kan , to investigate an out¬ 
break of these animals in orchards and in a large 
nursery. One orchard of 480 acres, containing 
about 26,000 apple trees, eight. to ten years 
planted, was found to be badly infested. About 
*Hawks and Owls of the United States, Dr. A. K 
Fisher, 1893. 
» 
