||The Mammals of Texas -
Western Harvest Mouse
Rodentia : Family Muridae : Reithrodontomys
Description. A medium-sized
harvest mouse; tail about as long as head and body; the
dark dorsal and light ventral stripes about equal in
width; ears pale flesh color (or buffy cinnamon);
upperparts brownish buff, darkest in middle of back;
underparts whitish. Differs from R. fulvescens in shorter tail, pale rather than blackish ears
basally; from R. montanus in
larger size, and lack of dark color at base of ears.
External measurements average: total length, 140 mm;
tail, 71 mm; hind foot, 18 mm. Weight, 10-16 g.
Distribution in Texas. Western Texas,
from the Panhandle southward to Trans-Pecos.
Habits. These mice prefer grassy
or weedy areas where adequate food and a certain degree
of protective cover are available, especially in the
vicinity of water. Meadows, marshes, and weed-covered
banks of irrigation ditches seem to offer optimum habitat
conditions. The species seldom is found in forested
They utilize the runways and
underground burrows of other rodents and frequently take
over vacated burrows of pocket gophers. The nest usually
is placed on the ground or slightly above it under some
protective cover such as a board, a clump of lodged
grass, or a tangle of weeds. It is a globular structure,
about 7 cm in diameter, composed of plant fibers, and
usually has only one opening. These mice are also known
to use the nests of marsh wrens in cattail marshes. They
appear to be strictly nocturnal and active throughout the
year. They are almost entirely vegetarians and feed on
the green parts and seeds of plants.
In Texas, the breeding season extends
through most of the year. Several litters a season seem
to be the rule. A captive female produced seven litters,
totaling 17 young, in one year. Litter size in wild mice,
based on 24 embryo counts, ranged from one to seven and
averaged about four. The gestation period is about 23
days. At birth the young mice are blind, naked, and
helpless and weigh from 1 to 1.5 g. By the end of the
first week they are covered with pigmented hair dorsally;
by the 11th or 12th day the eyes open, at which time the
mice begin to eat solid food. They are weaned by the 19th
day. Sexual maturity is reached in about 4 months.
These mice seldom are of economic
importance. They are utilized as food by a number of
flesh eaters, including weasels, foxes, owls, and snakes.