Saguache Meadow Vole 
95 
closely in external appearance that it is often quite impossible 
to distinguish them by external characters, and an examina- 
tion of the molar pattern is frequently necessary for their 
determination. 
Microtus pennsylvanicus modestus (Lat., modest). 
Saguache Meadow Vole. 
Arvicola modcsta Baird, N . Amer. Mamm., p. 535 (1857). 
Type locality. — Cochetopa Pass, Saguache Co., Colorado. 
Measurements. — Total length, 6.9; tail vert., 1.8; hind feet, 0.8. 
Description. — (From a specimen taken at Colorado Springs, 
March 9th): Above a dark grizzled brown, somewhat ochraceous; 
feet plumbeous; under parts a whitish gray; tail bicolor, blackish 
above, grayish below. In summer pelage lighter and more 
ochraceous. 
Distribution. — Bailey gives the distribution of this species as 
" Rocky Mountains and western plains from New Mexico to British 
Columbia and from the Black Hills of South Dakota to central 
Idaho and beyond, with slight variation, to the plains of the Colum- 
bia, mainly in Transition Zone . " It has been reported from Colorado, 
Wyoming, South Dakota, North Dakota, Montana, Idaho, Washing- 
ton, and Utah. In Colorado it has been recorded from Saguache, 
Costilla, Custer, Chaffee, Lake, Teller, El Paso, Adams, Yuma, 
Jefferson, Larimer, and Boulder counties, reaching at times an 
elevation of a trifle above 9,000 feet. 
Habits. — Some of the habits of voles, or field-mice of the 
genus Microtus are common to practically all the species. 
They live in underground burrows and have many little well- 
beaten roads or trails running from one burrow to another. 
In the burrows are placed the nests of soft grass or plant 
fibre, and nests are also made on the surface amongst the 
thick grass, weeds, or other vegetation. The nest is globular 
in form, with a chamber in the centre, and entrance through 
one or more holes on the side. 
They breed most of, if not all, the year round, and have 
from four to eight young at a birth. They thus increase 
with great rapidity in spite of their numerous enemies, which 
