SMALLER MAMMALS OF NORTH AMERICA 



423 



growths of sea oats, patches of saw palmetto, 

 or scrubby bushes. The homes of these mice 

 are usually in short burrows sheltered by 

 growing vegetation or under fallen palm 

 fronds. 



As in the case of many of our mammals, we 

 have scanty information concerning the life of 

 these attractive little animals, and it is sug- 

 gested that here lies a pleasant subject for in- 

 vestigation by some nature lover wintering in 

 Florida. 



THE BIG-EARED ROCK MOUSE (Pero- 



myscus truei and its relatives) 



(For illustration, see page 429) 



The numerous species of mice of the genus 

 Peromyscus in North America include a great 

 variety of little beasts, many of which are dis- 

 tinguished by beauty of form and color. One 

 of the most striking and picturesque individ- 

 ualities among these is found in the big-eared 

 rock mouse, which is characterized by its great 

 ears, a thick, soft coat of buffy brown fur, and 

 a long, well-haired tail. In size it exceeds the 

 common house mouse and even the white- 

 footed mice which share its haunts. 



This rock mouse is indigenous to the moun- 

 tainous regions of the West, from Colorado 

 and New Mexico to the Pacific and south to 

 the Cape Region of Lower California, and 

 down the Sierra Madre of Mexico to Oaxaca. 

 Within this area it divides into several not very 

 strongly marked geographic races. 



As implied by its common name, it is a char- 

 acteristic dweller among cliffs and ledges along 

 the mountain slopes or rocky canyon walls, 

 where it occupies the many crevices and little 

 caves. In California it ranges from near sea- 

 level up on the mountains to above 10,000 feet 

 altitude. Although showing a distinct prefer- 

 ence for rocky places, when available, some 

 races of this mouse adapt themselves to other 

 conditions and may be found on brush-grown 

 flats, where they live in brush heaps, old wood- 

 rat nests, and similar shelter. 



That they make their homes in places other 

 than cliffs in New Mexico was evidenced by a 

 thick, soft nest made almost entirely of wool, 

 found in a hollow juniper. They have several 

 litters of from two to six young each year, the 

 breeding period extending from spring to fall. 



In Arizona and New Mexico I found the 

 rock mouse most numerous in the belt of 

 junipers and pinyons and in the adjacent yel- 

 low-pine forest. The crevices of cliffs about 

 the Moki and Zuni Indian pueblos and in all 

 the rocky wilderness of that region, including 

 the Grand Canyon, are abundantly populated 

 with them. 



They search every nook about their haunts 

 and often visit cabins or temporary camps for 

 food, but do not usually take up their abode 

 in them as do the white-footed mice. When 

 foraging their movements are quick, and when 

 startled they make surprisingly long leaps. 

 Like others of their kind, they eat a great va- 

 riety of seeds and small nuts, quantities of 



which they lay up in winter stores. Pinyon 

 nuts, and especially juniper seeds, are their 

 favorite food. 



While of nocturnal habits, rock mice at times 

 wander forth in sheltered spots by day, and on 

 the few occasions I have seen them I have 

 been delighted with their grace and beauty, 

 their great ears and prominent shining black 

 eyes lending them an attractive air of alert in- 

 telligence. 



Throughout their lives they are in deadly 

 peril from predatory foes. Hawks and owfs 

 glide shadowlike along the faces of their rocky 

 homes ready to pick them up whenever they 

 venture into open view, while bobcats, skunks, 

 and weasels prowl about by night hunting their 

 furry victims. 



THE BROWN RAT (Rattus norvegicus 



and its relatives) 



(For illustration, see page 429) 



It is safe to assume that few readers need 

 an introduction to that world-wide pest vari- 

 ously known as the brown rat, house rat, wharf 

 rat, or Norway rat. Two European relatives, 

 the black rat and the roof rat, preceded the 

 brown rat to the New World and became 

 widely distributed. They resemble the brown 

 rat, but are much smaller and are soon killed, 

 driven away, or reduced to a secondary status 

 by their larger and fiercer cousin, which aver- 

 ages about sixteen inches in length, although 

 large individuals attain a length of more than 

 twenty inches and a weight of more than two 

 pounds. The black rat has nearly disappeared 

 from most of its former haunts in the United 

 States and the roof rat is mainly restricted to 

 southern localities with a mild climate. 



Neither the brown, black, nor roof rat has 

 any near relatives among native rats of Amer- 

 ica, and all may be distinguished from our 

 native animals by their coarser hair and long, 

 naked tails. 



The brown rat is believed to have first in- 

 vaded Europe from Asia in 1727, when hordes 

 of them swam the Volga River, and about the 

 same year it arrived in England on ships from 

 the Orient. Since then, traveling by ships and 

 by inland commercial routes, it has spread to 

 nearly all parts of the globe. In America it 

 is now established in human abodes through- 

 out the length and breadth of the continents 

 from Greenland to Patagonia. 



Wherever it goes the fierce and aggressive 

 spirit with which it is endowed qualifies the 

 brown rat more than to hold its own against 

 all rivals, while its mental adroitness and its 

 fecundity have largely nullified the constant 

 warfare being waged against it by all mankind. 

 Not content with infesting ships, dwellings, 

 stores, warehouses, and even the refrigerating 

 rooms of cold-storage plants in many areas, it 

 has established itself as an extremely destruc- 

 tive pest in the open fields. 



In towns it hides among stored merchandise, 

 in the hollow walls of buildings, in sewers and 

 other underground passages, or, as in the fields, 



