|The Mammals of Texas -
Northern Grasshopper Mouse
Rodentia : Family Muridae : Onychomys
Description. A stout-bodied, short-tailed
mouse similar to O. arenicola
but larger, heavier, and shorter-tailed; upperparts drab
brown; the nose, sides, cheeks, and underparts white;
tuft at anterior base of ear white and conspicuous; tail
usually less than 30% of total length and usually from 11/2
to two times as long as hind foot. External measurements
average: total length, 164 mm; tail, 42 mm; hind foot, 22
mm. Weight, 27-46 g, occasionally as much as 52 g.
Distribution in Texas. Throughout most of
western Texas (except the central part of the
Trans-Pecos) and the Rio Grande Plains of South Texas.
"predatory" mice occur chiefly in association
with sandy or powdery soils in grasslands or open
brushlands, but they are never very common as compared
with other small mammals.
They are wanderers and do not live long
in one place. They are reputed to usurp the burrows of
other small mammals rather than take the time to
construct their own. This is in keeping with their
pugnacious disposition. Vernon Bailey attributes to them
many of the habits of the weasel and compares one of
their calls with the howl of a wolf which "is made
with raised nose and open mouth in perfect wolf
form." Because of their short legs and chunky body
they are not fleet-footed, but they are expert at
dodging, twisting, and turning and in close quarters can
easily capture and overpower other mice their own size or
As the name implies, one of their chief
food items in season is grasshoppers. In addition,
numerous other kinds of insects, scorpions, small mice,
and a variety of plants contribute to their diet.
Captives are especially fond of raw liver and newborn
mice. Vernon Bailey and Charles Sperry report that animal
matter makes up nearly 89% of their natural food; plant
material comprises only 11%.
The breeding season extends at least
from May to October, as judged from pregnancy records.
The capture of half-grown young in the dark juvenile
pelage from February to September indicates that some
breeding occurs throughout much of the year. The bulk of
the young are born in May and June, however. The litter
varies from two to six; average about four.
The gestation period varies from 32 to
47 days, with the longer periods in lactating females. At
birth the young are pink and hairless (except for the
prominent vibrissae), and weigh about 2 g each. The eyes
and ears are closed, and the tail is characteristically
short and thick. Within 3 days the ears unfold, but the
eyes remain closed until the 19th or 20th day, at which
time the young mice are almost weaned. They are probably
evicted from the nest shortly after. Sexual maturity is
reached in about 3 months when the mice are still in the
soft, gray juvenile pelage.
Because of their fondness for insects
and small mice their economic status is either neutral or
Photo credit: R.D. Porter.