SMALLER AlAMMALS OF NORTH AMERICA 



483 



conifers, sometimes at an altitude of So 

 feet, and rarely or never descends to the 

 ground. 



PEEPS INTO FUR-FOLK HOMES 



The hom-es of small mammals vary 

 greatly. The species living in under- 

 ground burrows usually excavate an oval 

 chamber which is filled with fine vege- 

 table 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 ma- 

 terial, among the branches of bushes sev- 

 eral 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 incon- 

 spicuous 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 surround- 

 ings. 



In contrast to the protective coloration 

 are certain markings, like the cottony 

 white underside of the tail of the cotton- 

 tail rabbit, which renders the flight of 

 this animal conspicuous in the gloomiest 

 shades of the forest, or even on the ap- 

 proach of night, when it is impossible to 

 distinguish the animal itself. The white 

 underside of the tail of the antelope chip- 

 munk 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 efifect, 

 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 enor- 

 mous 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 ani- 

 mals, 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 chip- 

 munks 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 intona- 

 tion and character of the notes and calls 

 indicate plainly that they are used to con- 

 vey 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-scjuirrels have chat- 

 tering notes and sharp, whistling calls. 



In addition, some of the squirrels and 



