SMALLER MAMMALS OF NORTH AMERICA 



403 



by some enemy. They are sometimes found 

 several miles from shore, where they have 

 strayed out on the sea ice. 



In winter in the fur countries, in company 

 with field mice, they invade storehouses and 

 habitations in search of food. Among their 

 enemies are ravens and all northern hawks and 

 owls, as well as foxes, weasels, lynxes, bears, 

 and other beasts of prey of all degree. 



Within their underground tunnels and often 

 in dense vegetation on the surface lemmings 

 make warmly lined nests of grass and moss in 

 which their young, from two to eight in num- 

 ber, are born. The young appear at varying 

 times, thus indicating several litters each year. 



When taken alive, the old ones are fierce and 

 courageous, growling and fighting savagely ; but 

 several half-grown young brought me during 

 my residence in Alaska proved to be most 

 amusing and inoffensive little creatures. From 

 the first they permitted me to handle them 

 without offering to bite and showed no signs 

 of fear. 



They were kept in a deep tin box, from 

 which they made continual efforts to escape. 

 When I extended one finger near the bottom 

 of the box they would stand erect on their 

 hind feet and reach up toward it, using their 

 forepaws like little hands. If my finger was 

 lowered sufficiently they would climb up into 

 my hand and thence to my shoulder, showing 

 no sign of haste, but much curiosity, continu- 

 ally sniffing with their noses and peering at 

 everything with their bright beadlike eyes. 



They were curiously expert in walking on 

 their hind feet, holding the body in an upright 

 position and taking short steps. If anything 

 was held just out of reach above their heads, 

 as the point of my finger, they would continue 

 in an erect position for a considerable time. 

 At such times they would reach up with their 

 front paws and often spring up on their hind 

 feet for half an inch above the floor trying to 

 touch it. When eating they sat upright on 

 their haunches, like little marmots, and held 

 the food in their front paws. 



THE COMMON FIELD MOUSE, OR 



MEADOW MOUSE (Microtus penn- 



sylvanicus and its relatives) 



{For illustration, see page 420) 



The Pennsylvania meadow mouse is a small 

 species about as long in body as the house 

 mouse, but much more heavily proportioned. 

 Its head is rounded, the eyes small and bead- 

 like, the legs and tail are short, and the com- 

 paratively coarse fur is so long that it almost 

 conceals the short, rounded ears. 



It is a typical representative of a group of 

 small mammals commonly known as field mice, 

 or "bear mice," which includes a great num- 

 ber of species closely similar in general appear- 

 ance, but varying much in size. In England 

 they are termed voles, and large species living 

 about the water in England and northern 

 Europe are known as "water rats." 



Field mice are circumpolar in distribution 



and abound from the Arctic barrens, beyond 

 the limit of trees, to southern Europe and the 

 Himalayas, in the Old World, and to the south- 

 ern United States and along high mountains 

 through Mexico and Guatemala, in Central 

 America. They occur in most parts of the 

 United States except in some of the hotter and 

 more arid sections. 



As a rule field mice prefer low-lying fertile 

 land, as grassy meadows, but the banks of 

 streams, the rank growths of swamps and 

 marshes, the borders of damp woodlands, the 

 grassy places on Arctic tundras, or the dwarfed 

 vegetation of glacial slopes and valleys above 

 timber-line on high mountains furnish homes 

 for one species or another. 



Two, and even three, species of field mice are 

 sometimes found in the same locality, but each 

 kind usually occupies a situation differing in 

 some way from that chosen by the others. 

 Some occupy comparatively dry ground and 

 others, like the European water rat, live in 

 marshes and are almost as aquatic as the musk- 

 rat. Most species living about the water are 

 expert in diving and in swimming, even under 

 water. In streams inhabited by large trout 

 they are often caught and eaten by the fish. 



The presence of field mice is nearly always 

 indicated by smoothly worn little roads or run- 

 ways about an inch in width, which form a 

 network among the vegetation in their haunts. 

 These runways lead away from the entrances 

 of their burrows and wind through the vegeta- 

 tion to their feeding grounds. They are kept 

 clean and free from straws and other small 

 obstructions, so that the owners when alarmed 

 may run swiftly to the shelter of their burrows. 

 Fully conscious of their helplessness, meadow 

 mice are as cautious as the necessities of exist- 

 ence will permit. 



Their burrows are often in the midst of 

 grassy meadows, as well as under the shelter 

 of logs, rocks, tussocks of grass, or roots of 

 trees, and lead to underground chambers filled 

 with large nests of dry grass, which shelter the 

 owner in winter and often in summer. The 

 summer nests in many places, especially in 

 damp meadows or marshes, are made in little 

 hollows in the surface or in tussocks of grass. 

 In these nests several litters containing from 

 four to eleven young are born each year. 



It is rarely that an observer is located where 

 he can study the every-day lives of little ani- 

 mals like the meadow mice and at the same 

 time go on with his regular occupation. At 

 one of my mountain camps in Mexico I for- 

 tunately pitched my tent on a patch of lawn- 

 like grass in front of the ruins of an abandoned 

 hut. Runways of field mice formed a network 

 everywhere in the surrounding growth of grass 

 and weeds. 



For hours at a time as I worked quietly in 

 the tent the many mice, unconscious of my 

 presence, came silently along their little roads 

 through the tall vegetation to the border of the 

 short grass. Just within the shelter of the tall 

 growth they would each time stop and remain 

 watchfully immovable for a half minute, and 

 then, if everything was quiet, make a swift run 



