96 BaUey — Mammals of the District of Columbia. 



I have freqneiith' caught them along Rock Creek in traps set for white- 

 footed mice, and Mr. Preble has caught a number on the Potomac flats 

 below the city. That they are common outside of buildings is further 

 proved by the presence of their skulls in owl i^ellets. In 075 pellets of 

 barn owls taken in the Smithsonian tower Dr. Fisher found 452 skulls of 

 3Ius musculus.* 



Mus decumanus. The common Brown Rats are numerous in the city 

 and in the scattered buildings of the surrounding country. They show 

 less inclination to take to the woods than do the house mice, 3f. musmlus. 

 I have not found them at any considerable distance from buildings, but 

 in the previously mentioned 675 pellets of barn owls taken from the 

 Smitlivsonian tower were 134 skulls of this species.* 



Peromyscus leucopus. The White-footed Mice are common through- 

 out the woods in every part of the District. They are abundant along 

 Rock Creek near the Massachusetts Avenue and Connecticut Avenue 

 bridges, and on the west side of the Potomac and east side of Anacostia 

 River. I caught one in a trap at a hole in a stone w^all near Rock Creek, and 

 the next night caught a house mouse at the same hole. I have also taken 

 them at the same holes where Blarina brevicauda, Microtus i^eamylvaniciis, 

 and M. pinetonim were caught on the preceding or following nights, and 

 many of my specimens have been eaten in the traps by blarinas that 

 visited the traps before me. 



Neotoma pennsylvanica. Wood Rats are fairly common among the 

 rocks on the west side of the Potomac River a mile above Chain Bridge, 

 and it is jirobable that they occur all along the river cliffs up to the Blue 

 Ridge. No doubt they extend down to the end of the rocky bluff" oppo- 

 site Georgetown, or did before extensive quarrying disturbed their homes. 

 They are rock-dwellers, and will probably not be found near the District 

 away from the river cliffs. None have been taken on the east side of the 

 Potomac. 



Fiber zibsthicus. Muskrats are common in all suitable localities near 

 Washington. They are especially numerous along Rock Creek, where 

 they have increased rapidly since receiving the protection of the Zoologi- 

 cal Park. In favorite places the creek banks are perforated with their 

 burrows, plants cut for food are strewn along the shores, and the animals 

 may be seen swimming about in broad daylight. It will be interesting 

 to see how far this increase will go and by what circumstances it will be 

 limited. On the big marsh extending along both sides of Anacostia River 

 nuiskrat houses are common, and a few may be seen in the ponds and 

 marshes on the west side of the Potomac. Tracks and burrows are com- 

 mon along Beaver Dam Branch, on the east side of Anacostia River, and 

 still more common along the arm of the Potomac that flows around the 

 east side of High Island. Large numbers of skins are brought to market 

 by negro trappers from lower down the river. 



* Science, N. S., Ill, p. G23, April 24, 189(5. 



