20 AX ECONOMIC STUDY OF FIELD MICE. 
Lows: Total length, L25 mm. (about 5 inches) : tail vertebrae, i^o mm. 
(0.78 inch) ; hind feet, 16.3 nun. (0.64 inch)." 
Owing to their peculiar habits, pine mice arc not so well known as 
are meadow mice. Their natural habitat is the forest, although they 
are by no means restricted to pine woods or forested areas. While 
often inhabiting pine woods and the edges of adjacent fields, they live 
also in forests and copses of deciduous trees, usually on uplands. 
The life of pine mice is largely spent in underground tunnels, 
which so closely resemble those of the mole that generally they are 
mistaken for the work of that animal. The ridges of loose soil over 
the tunnel are exactly like those thrown up by the mole, but the inner 
diameter of mouse tunnels is less. When moles and pine mice live 
in the same vicinity, the mice often use the runways made by 
the moles. It is this habit that has helped to bring moles into dis- 
repute with farmers, who blame them for damages inflicted upon 
potatoes and other crops by pine mice. 
In marked contrast with the pine mouse, the mole (genus Scalopu* | 
is almost exclusively carnivorous, eating mainly earthworms and 
insects. While it sometimes cuts off the roots of growing plants 
when they interfere with its tunneling operations, it apparently eats 
no roots. Stomach examinations of moles show that they eat a very 
small percentage of vegetable matter, and this mainly waste corn or 
other grain previously softened by long contact with wet soil. On 
the other hand, pine mice eat little insect food, if any, and are largely 
consumers of vegetable substances. Nearly always when moles are 
charged with destroying root crops, the real culprits are pine mice. 
Thin, open woodlands used for pasture, and thickets along the 
edges of forests are favorite resorts of pine mice. Like nearly all 
voles, they prefer moist soil, but it must also be loose and somewhat 
sandy. From their intricate tunnels under the leaf mold frequent 
burrows descend into the soil. Some of these burrows are utilized 
as nesting places. Xests are built also at the surface of the ground, 
under fallen logs, brush heaps, flat stones, fences, or other shelter. 
The number of young at a birth evidently averages less than is 
usual in the genus Microtus* as is shown by the small number of 
mammae. Observations as to the number of litters in a season seem 
to be lacking, but the rate of reproduction is probably less in the 
pine mice than in any other American group of field mice. Bla>in^ 
says concerning M. suMerraneus of Europe, that '* it produces five 
or six times a year three to five young, which are blind for ten days 
after birth;" & and this statement is probably true, with slight modi- 
fication, for all the species of the group. To compensate for slower 
multiplication, their liability to attack by natural enemies is much 
»N. A. Fauna No. 17. p. 64. 1900. 
& Naturgeschichte der Saugethiere Deutschlands, p. 390, 1857. 
