104 



NORTH AMERICANi FAUNA 66 



f, nigrans in the Eastern Shore and Western Shore sections, and is re- 

 placed by that subspecies in the southern Eastern Shore and southeast- 

 ern Western Shore sections. (See fig. 38.) 



Distinguishing characteristics. — Teeth 1/1, 0/0, 0/0, 3/3, = 16; 

 molar teeth rootless and persistently gro^\T.ng; coloration of upper- 

 parts dull chestnut brown, darkest along the middle of the back; 

 underparts grayish white, or buffy white; feet grayish brown; tail 

 dusky above, paler below, fur overlaid with coarse guard hairs; 

 tail less than a third of total length of animal. 



This vole is similar in appearance to the red-backed mouse 

 ( Clethrionomys gapperi) , but is larger and more brownish in colora- 

 tion, and lacks the red dorsal band. It is also similar in appearance to 

 the pine vole {Pitymys pinetorum) but has coarser pelage, bigger ears, 

 and a longer tail. It differs from the southern bog lemming {Synap- 

 tomys cooperi) in its coarser, shorter pelage and much longer tail, 

 and in lacking grooved upper incisors. 



Mea^rements. — ^Eleven adults from the vicinity of Oldtown, 

 Allegany County, have the following external and cranial measure- 

 ments: Total length 169.2 (161.0-187.0) ; condylobasal length of skull 

 28.5 (28.1-29.0); zygomatic breadth 15.4 (14.8-15.9); interorbital 

 breadth 3.6 (3.4-4.0) ; maxillary toothrow 6.9 (6.5-7.3). Males average 

 somewhat larger than females. 



Habitat and habits. — This vole is nimaerous in fields and meadows 

 throughout the State. It is also common in marshes and similar areas 

 with heavy growth of grass ; occasionally it is found in orchards and 

 open woodland if the gromid cover is grassy. This is one of the most 

 abundant mammals in Maryland. 



Meadow voles construct extensive runways on the surface of the 

 ground. These runways are about 1% inches in diameter and run in 

 a network under the cover of dead grass. They are sometimes the 

 only sign of the presence of these voles in an area. If the runway is 

 fresh and is being used, there will generally be droppings and cut 

 pieces of grass at various intervals along it. The nest of the meadow 

 vole is usuall}^ constructed on the surface of the ground in one of the 

 runways. It is bulky, generally about 5 or 6 inches m diameter and 

 3 or 4 inches deep, usually covered, but sometimes not. 



The meadow vole is active both day and night. It is cyclic in nature 

 and the reproductive habits vary from year to year (Hamilton, 1937). 

 It is polyestrous and may breed the year round, although in Mary- 

 land there is a tendency not to breed during the coldest part of win- 

 ter. The females reach puberty and begin to breed at 25 days of age, 

 and from six to eight young generally comprise a litter. The gestation 

 period in this species is 21 days, or a little less, and as many as 17 

 litters may be produced in a year. 



