Onychomys leucogaster, the Northern grasshopper mouse, can be found from southwestern Canada throughout the western United States into northwestern Mexico. Its distribution ranges from the Pacific coast to western Minnesota and Iowa.
Onychomys leucogaster live in shortgrass prairies, sand dunes and in sage brush desert. These are primarily areas with sandy soil in which they build their burrows. Compared to other species of the same genus, northern grasshopper mice prefer higher elevations and so are also commonly found in canyon lands.
Northern grasshopper mice have white ventral fur, and dorsal fur that ranges from brown to pink. The tail is short, averaging 42 mm in length, with a white tip. This is approximately one third of total body length, which averages 164mm. The hind feet average 22mm.
Juvenile O. leucogaster have white ventral surfaces, however the dorsal fur ranges from light to dark grey. At 57 to 62 days of age, fur color changes to the cinnamon color of adult pelage. This process takes up to 20 days. Teeth are smaller than many other mice, with pointed cusps reflecting their carnivorous diet.
Breeding occurs throughout the year but more frequently between May and October.
When a male and female O. leucogaster come within 10 to 15 cm of each other, they begin to circle and smell the anal area of the other sex. This is followed with the male following the female until he mounts her from the rear in what is called a copulatory lock. This occurs in 10 phases and requires around three hours to complete. Each phase is ended when the female moves away and begins to groom herself. Studies show that pairs that engage in only a few "locks" have little reproductive success.
The female rears an average of four young which she spends much time caring for until they are 14 days old. The male does not contribute to this care. This is a relatively slow maturation rate and is thought to be connected to learning the predatory behaviors that the young will need to survive. Several litters are born to a female each year.
Northern grasshopper mice are primarily solitary. Dominance hierarchies are established when contact is made with other grasshopper mice. If grasshopper mice of the same sex are put together in a closed environment, the socially dominant individual will kill the other within 72 hours of initial contact. Although this is typically only true of same sex encounters, some females have been known to kill their mates.
Onychomys leucogaster are nocturnal and hide in an intricate burrow system during the day. Three main types of burrows are built. The first is a nest burrow in which these mice spend the majority of their time resting and escaping from the heat of the sun. They also build emergency burrows for escaping predators and storage burrows in which to hide seeds and other preservable food items for when live prey is not available.
Since grasshopper mice are active year round and nocturnal, their activity is influenced by lunar phases, photoperiod, and daily weather. On clearer nights, when the moon is full, they are more active.
The shrill cry of the northern grasshopper mouse is thought to be both a hunting call, as stated above, as well as a mating call.
O. leucogaster are unique among mice in that the majority (almost 90%) of the diet is other animals. They feed primarily on insects, including grasshoppers, scorpions, beetles, crickets, and moths. They have been known to eat rodents as well, including other O. leucogaster.
Northern grasshopper mice stalk their prey in an almost feline manner letting out a shrill cry before attacking.
In the stomach of these creatures, two of the glands are enclosed in a 'pocket' of tissue. This is thought to protect them from damage by the chitin from their insect prey.
Since the diet of this species consists of mainly insects and very few plants (such as commercially produced grains), it has been suggested that O. leucogaster may be able to serve as a natural predator against pests that commonly disturb agriculture.
They also make interesting pets, and become tame in captivity.
In shortgrass prairies northern grasshopper mice add prairie birds to their diet. This may result in the loss of a variety of birds because of predation by this species and other mammalian predators.
Northern grasshopper mice have suprisingly few predators. Other than humans, their primary predators are owls and other nocturnal birds of prey.
Erika Detweiler (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
1990. Grzimek's Encyclopedia of Mammals. New York: McGraw-Hill Publishing Company.
"Declines of shortgrass prarie birds" (On-line). Accessed November 21, 1999 at http://www.mesc.usgs.gov/projects/decshortbirds.html.
"The Mammals of Texas" (On-line). Accessed November 21, 1999 at http://www.nsrl.ttu.edu/tmot/onycleuc.htm.
McCarty, R. January 6, 1978. Onychomys leucogaster. Mammalian Species, 87: 1-6.
Nowak, R. 1999. Walker's Mammals of the World. Baltimore: The Johns Hopkins University Press.