16 



THE MUSKRAT. 



brown rats, house mice, field mice, lemmings, wood rats, squirrels, 

 and other gnawers. 



In winter the chief food of muskrats consists of the roots of aquatic 

 plants — pond lilies, arums, sedges, and the like — but in some localities 

 the animals feed on mussels and also on carp and other sluggish 

 fish that bury themselves in mud. When ponds are frozen over, musk- 

 rats are almost wholly restricted to food accessible under the ice, 

 but in rare cases they have been knowm to leave the water and burrow 

 under the snow in search of the crowns of grasses and sedges. 



In wooded marshes near Washington, D. C., the winter food of 

 muskrats seems to be largely roots and stems of the golden club 

 (Oi'ontium aguatJnnii) . At New Richmond, Mich., in November, 

 1908, W. L. McAtee, of the Biological Survey, found the animals 

 feeding almost entirely on fleshy tubers of a large sedge, the river 

 bulrush {Scirpus flu viatilis) . The writer examined 15 of the stomachs 

 collected by Mr. McAtee at this place and found the contents to con- 

 sist largely of the finely ground, starchy material from this tuber, in 

 some instances mixed w^ith fibrous bits of stems and roots of other 

 aquatic plants. No animal matter was found. Some of the stomachs 

 contained over 2^ ounces of food, weighed wdien moist. 



The fact that muskrats swim long distances under the ice is well 

 known, and the generally accepted explanation is the following: 

 When more oxygen is needed the animal comes to the top of the water 

 and exhales its breath against the ice. After waiting a moment for 

 the air bubble to take up oxygen the animal reinhales it and then 

 continues its journey. Thus far, the writer has failed to observe 

 this habit. He has several times watched muskrats swimming under 

 the ice and coming to the surface to breathe, but in every instance he 

 was satisfied that there w^as air in the space below the ice. 



Although the muskrat secures air under the ice, it does not obtain 

 enough to last it while feeding. For this purpose it must reach the 

 outer air. The winter houses are not air-tight, and are used to some 

 extent as dining places; but much of the food is consumed just out- 

 side of air holes in the ice, w:hich are kept open by frequent use. 

 Roots, leaves, stems, and grasses are hauled to the surface through 

 these openings; and on these winter " draw-ups " the animals sit 

 while eating. Sometimes the draw^-up is roofed over Avith stems of 

 plants, forming a house large enough to shelter a single muskrat. 



In summer the muskrat's menu is far more extensive. It can then 

 choose from many aquatic plants — roots, stems, leaves, and fruit — 

 and in addition can obtain supplies from near-by fields or woods. 



Muskrats are fond of nearly all garden vegetables — cabbage, onions, 

 carrots, parsnips, beets, peas, beans, celery, and the like — and they 

 frequently do considerable damage in gardens close to their haunts. 



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