60 FUR FACTS 



level of the water. They often rise to within a few inches of the 

 surface of the ground and are frequently protected above by roots, 

 trees and shrubs, or by thickly matted turf. These tunnels ex- 

 tend 10 to 50 feet into the bank and terminate in a roomy chamber 

 which sometimes contains a bulky nest composed of dried vegetation. 

 Usually two tunnels lead from the nest to the water, and often a 

 tunnel has two branches or outlets. 



When burrows can be made, muskrats occupy them in winter and 

 summer; but in shallow ponds and marshes, and especially in north- 

 ern latitudes, the entrances are often closed by ice in winter. In 

 such situations and when banks are not suitable for burrows, houses 

 become a necessity, but they are seldom seen along the borders of 

 deep ponds and canals. 



As cold weather approaches, the animals become very active, 

 adding to their old winter houses, building new ones, and deepening 

 channels that lead to houses and burrows. They do not hibernate, 

 and, aside from the vegetation of which their houses are made, seem 

 to make little provision for the winter. However, some of the sur- 

 plus food collected may be found in their burrows at almost any time. 



BREEDING 



The Honorable David E. Lantz in his comments on muskrat 

 breeding says "It is now well established that muskrats breed from 

 three to five times in a year and that the litters average from 6 to 8 

 young. The early spring litters are usually less in number, and those 

 of midsummer are somewhat above the average. The muskrat in 

 their breeding habits are very much like field mice. Where they are 

 depleted by vigorous winter trapping, they are replenished before 

 the opening of another season, and it can be seen from a glance that 

 they breed very fast and multiply quickly. Normally the animals 

 mate in March and the first litter is born in April; the second litter 

 is due in June or early in July; and a third in August or September. 

 In favorable seasons a fourth or even a fifth litter may be produced." 



MIGRATIONS 



Muskrats sometimes wander over fields and along highways quite 

 a distance from water. This occurs late in fall, early in spring, or 

 during severe droughts late in summer. The causes are not under- 

 stood, although the spring movement has generally been attributed 

 to the beginning of the mating season. When met away from water, 

 the animals sometimes show considerable ferocity and have been 

 known to attack persons savagely without apparent provocation. 



