Figure 7. — Clump of three-square bul- 

 rush (Scirpiis olneyi). The fibrous 

 roots are used extensively in house 

 construction, and the larger, runner 

 roots are highly prized by the muskrat 

 for food. 



aquatic or swamp plants. Conse- 

 quently, their presence in an area is 

 detected by the evidences of their 

 activity rather than by observations 

 of the animals themselves. 



Nesting or dwelling houses 



The muskrat nesting or dwelling 

 house, also known as a bed or lodge, 

 is constructed of the fibrous-root 

 masses and stems of aquatic plants 

 growing in the area (fig. 7). It 

 may rest on the bottom of a shallow 

 pond or on clumps of marsh grasses. 

 Built by heaping up freshly cut 

 material, the dome-shaped nesting 

 house is distinguished by its large 

 size, elliptical shape, and peaked or 

 lopsided const ruction ( fig. 8 ) . The 

 heights of the houses vary from 16 

 inches to 4 feet, depending on the 

 supply of vegetation available, se- 



verity of the season, and fluctua- 

 tions in the water levels. The walls 

 are from 4 inches to a foot thick, 

 and openings in them are closed 

 with mud. This keeps the nest 

 warm in winter and cool in summer. 

 When an inhabited house is opened 

 during the fall or winter, a dry 

 well-lined nest, or chamber, is found 

 above the water line with several 

 "runs" down to plunge holes under 

 the water. 



Feeding shelters 



The feeding shelter, or hut, is a 

 place to which the muskrat can 

 bring food and eat it protected 

 from its enemies and from the 

 weather. Several feeding shelters 

 may be constructed near the dwell- 

 ing house at convenient distances, 

 their number and sturdiness de- 

 pending on the need. 



The feeding shelter is distin- 

 guished from the dwelling house by 

 its smaller size, roughly circular 

 outline, low height of 12 to 16 inches 

 above water level, and more round- 

 ed and uniform shape (fig. 9). 

 When it is opened a small central 

 feeding platform containing plant 



Figure 8. — Typical muskrat house in 

 Maryland "three-square" marsh in 

 winter, showing mud runway and fresh 

 patching. 



6 



