MAMMALS OF MARYLAND 



93 



1949 to June 1950, 23 of these mice were captured by Stickel and 

 Warbach. 



According to W. H. Stickel (1951, p. 26) the Maryland specimens 

 of this race were most often caught in corn and in young wheat ; only 

 occasionally were they found in hay or tall wheat. He says that the 

 subspecies seems to be precariously established at the Patuxent Re- 

 search Center and was not common, nor did the numbers appear to 

 increase, during the year the area was extensively studied. 



P&romyscus m. hairdii is essentially a subspecies of the prairie re- 

 gion of the upper Mississippi Valley. In recent years it appears to have 

 been extending its range eastward consequent with the deforestation 

 of wide areas of land in the eastern United States. In 1909, Osgood 

 (1909, p. 79) knew it only from as far east as Ohio. In 1934, Mitchell 

 (1934, p. 71) recorded it from Meadville, Pa., and in 1938, Moulthrop 

 (1938, p. 503) listed it from Elba, Genesee County, N.Y. Hamilton 

 (1950, p. 100) recorded the first appearance of hairdii in 1947 at Ithaca, 



Y., an area that had been heavily trapped for the previous 20 years, 

 and mentioned the capture of the subspecies at North Harrisburg, 

 Dauphin County, Pa., the first record from east of the Appalachian 

 Mountains. More recently, Peacock and Peacock (1962, p. 98) have 

 taken specimens from the area being developed into Dulles Airport, 

 near Chantilly, Fairfax County, Va. 



Stickel (1951, p. 26) states that no doubt the animal is expanding 

 its range by natural means in consequence of artificially created habi- 

 tats, but the possibility of accidental transportation is considerate. 

 It may be that the mouse has succeeded in crossing the heavily forested 

 Appalachian Mountains by following the grass-lined banks and 

 shoulders that line the roads in that area. It would in this way remain 

 ecologically separated from Peromyscus m. nubiterrae^ the race in- 

 habiting the dense forests of the Appalachians. 



Just how widely hairdii is distributed in Maryland is unknown. No 

 additional specimens have been taken since Stickel and Warbach col- 

 lected those at the Patuxent Research Center in 1939. I have trapped 

 many cultivated fields in central Maryland and grassy roadsides in 

 the western part of the State with the hope of obtaining additional 

 records, but without success. The recent records from nearby Chantilly, 

 Va., however, lead me to believe that the subspecies is probably widely 

 distributed, although perhaps scarce as regards total numbers, in open 

 fields throughout Maryland. 



These mice feed largely on seeds, grain, and the ripe heads of grasses ; 

 berries and numerous insects are also consumed. The nest is built 

 slightly underground, or on the surface, and usually placed under 

 some object, such as a board, fallen tree limb, rock, or old pasteboard 

 carton. The breeding season generally begins in early March and ex- 



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