SMALLER MAMMALS OF NORTH AMERICA 



471 



nests thus safely located they have one litter 

 containing an average of from four to six, but 

 sometimes numbering up to twelve, young a 

 year. They are born at any time from April 

 to June, according to the latitude. The number 

 of young in a litter is enough to render weasels 

 very abundant, but this is rarely the case, and 

 raises the question as to the influence which 

 holds their number in check. 



They are both nocturnal and diurnal, ap- 

 parently in almost equal degree, since they are 

 frequently observed hunting in the middle of 

 the day, while their nocturnal raids on poultry 

 houses testify to their activities at night. When 

 hunting they appear like sinister shadows and 

 are persistent in pursuit. The young commonly 

 remain with the female until nearly or quite 

 grown and follow her closely on hunting trips. 

 It is interesting to see a pack of these deadly 

 carnivores working, the mother leading and the 

 young skirmishing on all sides, now spreading 

 out, now closing in. like a pack of miniature 

 hounds. On these family hunting parties, how- 

 ever, they usually keep close to the rocks, logs, 

 brush, or other cover. 



Themselves subject to the law of fang and 

 claw, weasels are killed and eaten by wolves, 

 coyotes, foxes, and various birds of prey. Their 

 very lack of fear perhaps in many cases leads 

 to their destruction. 



These representatives of the primitive wood- 

 land life continue to occupy practically all of 

 their original range. They visit farms in all 

 parts of the country and I have seen them near 

 the outskirts of Washington. 



It is well that weasels are not abundant, for 

 beasts with such innate ferocity and love of 

 killing would otherwise be a menace to the 

 existence of many useful species of birds and 

 mammals, especially the game birds. In many 

 places they live almost entirely on mice, and 

 there they should be left unmolested ; but 

 whenever they locate in the vicinity of a chicken 

 yard the owner will do well to take proper 

 measures for protection. 



THE LEAST WEASEL (Mustela rixosus 



anci its relatives) 



(For illustration, see page 452) 



In addition to the larger members of the 

 tribe briefly described in the foregoing sketch, 

 the true weasels include another group of 

 species, so small they may appropriately be 

 termed the dwarfs of their kind. They vary 

 from a half to less than a fourth the size of 

 the larger weasels, but have the same char- 

 acteristic form and proportions, except that the 

 tail is very short and never tipped with black. 

 Like the larger species, they change their brown 

 summer coat for white at the beginning of 

 winter and back again in spring. 



The least weasels are also circumpolar in 

 distribution, but are limited to the northern 

 parts of Europe, Asia, and North America. 

 In England and other parts of the Old World 

 the group is represented by the well-known 



species Mustela vulgaris. In North America 

 several species are known which, between them, 

 share all the continent from the Arctic coast 

 south to Nebraska and Pennsylvania. On the 

 desolate islands extending from the mainland 

 far toward the Pole their place seems to be 

 taken by the ermine. 



The dwarf weasels appear to be less numer- 

 ous and, as a consequence, less known in most 

 parts of America than in England and north- 

 ern Europe. Our most northern species, 

 Mustela rixosa, sometimes called the ''mouse 

 weasel," occupies Alaska and northern Canada 

 and has the distinction of being the smallest 

 known species of carnivore in the world. In 

 this connection it is interesting to note that 

 in Alaska we have associated on the same 

 ground the least weasel and the great brown 

 bear, the smallest and the largest living car- 

 nivores. 



Least weasels are characterized by the same 

 swift alertness and boldness so marked in the 

 larger species. In fact they are, if possible, 

 even quicker in their movements. Once when 

 camping in spring among scattered snowbanks 

 on the coast of Bering Sea, I had an excellent 

 opportunity to witness their almost incredible 

 quickness. Early in the morning one suddenly 

 appeared on the margin of a snowbank within 

 a few feet, and after craning its neck one way 

 and the other, as though to get a better view 

 of me, it vanished, and then appeared so 

 abruptly on a snowbank three or four yards 

 away that it was almost impossible to follow 

 it with the eye. It was beginning to take on 

 its summer coat of brown and was extremely 

 difficult to locate amid the scattered patches 

 of snow and bare moss of the tundra. Cer- 

 tainly no other mammal can have such flash- 

 like powers of movement. 



They feed mainly on mice, lemmings, shrews, 

 small birds, their eggs and young, and insects. 

 Mice furnish a large proportion of their pre} r 

 and weasels have often been seen following the 

 runways of field mice. Their small size enables 

 them to pursue mice into their underground 

 workings as readily as a ferret enters a rabbit 

 burrow. They- also climb trees and bushes with 

 great agility, although nearly always seeking 

 their victims on the ground. The mice upon 

 which they prey are often so much larger than 

 the weasels that they cannot be dragged into 

 the dens. The weasels continue in full activity 

 throughout the winter and constantly burrow 

 into the snow in search of their prey. In the 

 snow or in the ground the holes of this animal 

 are about the diameter of one's finger. 



In the Old World the small weasels are re- 

 ported to have several litters in a season, each 

 containing five or six young. At Point Barrow, 

 Alaska, a female captured on June 12 still con- 

 tained twelve embryos. This indicates that 

 only one litter a year would be born there, and 

 that Mustela rixosa is more prolific than its 

 European representative. 



In the more southern latitude least weasels 

 live in forests and about farms, sheltering 

 themselves under logs, brush piles, stone walls, 



