SMALLER MAMMALS OF NORTH AMERICA 



401 



ern species and those on the colder mountain 

 slopes must make large store against the win- 

 ter needs. Their food consists mainly of seeds, 

 leaves of several plants, and of little plants just 

 appearing above ground. Tiny cactus plants 

 and the saline fleshy leaves of Sarcobatus are 

 often among the kinds gathered for food. 



The big Dipodomys spectabilis appears to be 

 more social than most of its kind, as several 

 may be caught in a single mound, and, as al- 

 ready said, well-worn trails lead from mound 

 to mound. A little noise made just outside one 

 of these mounds usually brings a reply or chal- 

 lenge in the form of a low drumming or thud- 

 ding noise, no doubt made by the animal rap- 

 idly striking the ground with its hind feet like 

 a rabbit or wood rat. 



When caught they at first struggle to escape, 

 but, like a rabbit, do not offer to bite, and soon 

 become quiet. They have from two to six 

 young, which may be born at any season. 

 Nothing appears to be known concerning the 

 number of litters in a year. 



When in camp at San Ignacio, in the middle 

 of the desert peninsula of Lower California, I 

 had an unusual opportunity to learn something 

 of the habits of one of the smaller species of 

 kangaroo rat abundant there. The moon was 

 at its full, and in the clear desert air its radi- 

 ance rendered objects near at hand almost as 

 distinct as by day. Scattered grains of rice 

 and fragments of food on the ground about 

 the cook tent attracted many kangaroo rats and 

 pocket mice. 



During several nights I passed hours watch- 

 ing at close range the habits of these curious 

 animals. As I sat quietly on a mess box in 

 their midst both the kangaroo rats and the 

 mice would forage all about with swift gliding 

 movements, repeatedly running across my bare 

 feet. Any sudden movement startled them and 

 all would dart away for a moment, but quickly 

 return. 



Although the kangaroo rats did not become 

 so fearless and friendly as the pocket mice, 

 they were so intent on the food that at times 

 I had no difficulty in reaching slowly down and 

 closing my hand over their backs. I did this 

 dozens of times, and after a slight struggle 

 they always became quiet until again placed on 

 the ground, when they at once renewed their 

 search for food as though no interruption had 

 occurred. 



One night, to observe them better, I spilled 

 a small heap of rice on the sand between my 

 eet. Within two or three minutes half a dozen 

 kangaroo rats had discovered it and were bus- 

 ily at work filling their cheek pouches with the 

 grains and carrying them away to their store 

 chambers. 



While occupied in this rivalry for food they 

 became surprisingly pugnacious. If one was 

 working at the rice pile and another rat or a 

 pocket mouse approached, it immediately dart- 

 ed at the intruder and drove it away. The 

 mode of attack was to rush at an intruder and, 

 leaping upon its back, give a vigorous down- 

 ward kick with its strong hind feet. Once I 

 saw a pocket mouse kicked in this way. It 

 was knocked over and for a minute or more 



afterwards ran about in an erratic course, 

 squeaking loudly as though in much pain. 



Sometimes the pursuit of one kangaroo rat 

 by another continued for twenty yards or more. 

 By the time the pursuer returned another 

 would be at the rice pile and it would imme- 

 diately dash at the victor of the former fray 

 and drive him away. In this way there was a 

 constant succession of amusing skirmishes. 



Sometimes an intruder, bolder than the oth- 

 ers, would run only two or three yards and 

 then suddenly turn and face the pursuer, sit- 

 ting up on its hind feet like a little kangaroo. 

 The pursuer at once assumed the same nearly 

 upright position, with its fore feet close to its 

 breast. Both would then begin to hop about 

 watching for an opening. Suddenly one would 

 leap at the other, striking with its hind feet 

 exactly like a game cock. When the kick 

 landed fairly on the opponent there was a dis- 

 tinct little thump and the victim rolled over on 

 the ground. After receiving two or three 

 kicks the weaker of the combatants would run 

 away. 



The thump made by the kick when they were 

 fighting solved the mystery which had covered 

 this sound heard repeatedly during my nights 

 at this camp. The morning light revealed a 

 multitude of little paired tracks made by the 

 combatants in these battles. Such tracks in 

 the sand have been referred to as the "fairy 

 dances" of these beautiful little animals, but 

 the truth revealed proves them to be really 

 "war dances." 



THE BANDED LEMMING (Dicrostonyx 

 nelsoni and its relatives) 



(For illustration, see page 417) 



Banded lemmings are unique among the 

 mouse tribe in their change from the rufous 

 brown, or gray summer coat to pure white in 

 winter. With the assumption of the white 

 winter fur a thick, horny, padlike growth de- 

 velops on the underside of the two middle 

 claws of the front feet, which is molted in 

 spring when the winter coat is lost. For an 

 animal living in the far North the usefulness 

 of a white coat in winter is evident, but no good 

 reason is apparent for these curious claw-pads. 



The summer coat varies remarkably in color 

 and color pattern, and many of the lemmings 

 in their beautiful shades of chestnut, browns, 

 or grays are very handsome. They are more 

 heavily proportioned than field mice and the 

 very long fluffy fur, which completely conceals 

 the rudimentary ears and tail, tends to exag- 

 gerate their size. 



The banded lemmings form a strongly 

 marked group, containing a number of species 

 inhabiting circumpolar regions. In North 

 America they occur nearly everywhere in the 

 arctic and subarctic parts, including Greenland, 

 most of northern Canada, including the Arctic 

 islands, and a large part of Alaska, including 

 some of the Aleutian Islands. 



They range as far northward as vegetation 

 affords them a proper food supply and have 

 been well known to many of the explorers of 



