Onychomys
leucogaster
(Northern Grasshopper
Mouse)
Description:
This species has at least two
color phases: grayish above, or cinnamon-buff to reddish
brown, they are white underneath. As juveniles, they are dark gray. Their
tail is shorter, less than half their body length, but it is bicolored with
a white tip. Total length is 5 1/8 to 7 ˝ inches (130-190 mm), tail length is
1 1/8 to 2 3/8 inches (29-61 mm), and they weigh about 1 to nearly 2 ounces
(27-52 g). They have noticeably long front claws and large front feet.
Range:
From south-central Canada,
south through Great Plains to northern Mexico. Extends west through Great
Basin and southwestern deserts of Arizona and New Mexico, and also occurs
in Rocky Mountains.
Habitat:
They occur, in areas with sandy, diggable soil and sparse vegetation, in
grasslands, shrub steppe, overgrazed pastures,
weedy roadside ditches, and semi-stabilized sand dunes. In Idaho, species is
most numerous in sagebrush areas, but usually in fine sandy or silty soils.
Diet:
Eats 70-90% animal material, primarily
arthropods (grasshoppers, beetles, spiders, larval Lepidoptera), but will also eat plant
material and small rodents, especially in winter.
Ecology:
Grasshopper mice are
active throughout the year, although their activity is greatly reduced during
the full moon or heavy, prolonged rainfall. They are nocturnal but their activity seems
influences by lunar phases. They occupy underground burrows when inactive which
they plug for moisture retention and temperature regulation. They also dig small
"retreat burrows" when away from their nest burrow. They may store seeds. They
usually occur at relatively low densities, but may become a controlling factor
for prey items. Their predatory behavior is well known. They are active predators
killing prey as formidable as scorpions. They kill other rodents by gripping
them with their long, front claws and biting the prey. They appear to be territorial
and actually mark their territory with scent glands. They also emit shrill whistles
that seem to function in advertising their presence, much like larger predators
like coyotes. They are aggressive toward others of their species, which may
be associated with their territorial behavior. They maintain an unusually large
home range (or territory) for a small mammals; up to 5.8 acres (2.3 ha).
Reproduction:
Breeding
occurs from late spring to early fall, and Gestation lasts about 32 to 38 days.
litter size is typically 3 to
4 young, but ranges from 1 to 6. Males assist in caring for the young by bringing
insects in to the young. This is very different from typical rodent behavior
where males rarely help care for young. Young develop rapidly, and seem to act
like young dogs or coyotes by fighting and seeming preparing for their predatory
life style. Young reach sexual maturity at 3-4 mo.
Conservation:
Status: | Unprotected nongame species |
Global Rank: |
|
State Rank: |
S4 |
Important State References:
Reynolds. T.D. 1980. Effects of some
different land management practices on small mammal populations. J. Mammal.
61:558-561.