Field Guide/Mammals/Northern Grasshopper Mouse
|Onychomys leucogaster (Northern Grasshopper Mouse)|
Size: Ranging from 4.5-7.5 inches (12-19cm) in length overall, tail between 1-2 inches (3-6cm). Weighing roughly 1.8 ounces (52g) at maturity.
Description: The northern grasshopper mouse is a bulkier rodent (though still quite small) with a greyish to pale brown fur on top and a white underbelly. Its tail is short and thick generally with a white tip.
Similar Species: Besides a shorter tail and larger forefeet, the northern grasshopper mouse differs in that it’s primarily a carnivore and has adapted larger teeth to kill prey. Similar species eat mostly nuts seeds and only occasionally insects.
Range: The northern grasshopper mouse inhabits a wide area. From a line beginning in northern Mexico through Texas and the western half of Minnesota into Manitoba, extending west to the coast. They tend to be territorial so population density is low.
Habitat: This species does well in western prairies, plains, sparse pastures and deserts with minimal vegetation, commonly inhabiting the burrows of other animals. They have also adapted to more mountainous regions in many cases. 
Diet: Primarily carnivorous (70-90%), mostly insects - occasionally poisonous, reptiles, other mice, small birds and other creatures. Grasshopper mice will eat plants when other food is scarce and have been known to store seeds in preparation for winter survival.
Activity: Primarily Nocturnal and active throughout the year, reduced during a full moon likely because of exposure to other predators, likewise during heavy rainfall because of difficulty hunting. Mated pairs defend their territory against other grasshopper mice and will bark or howl to ward off intruders. 
Reproduction: Gestation ranges from 32-38 days, litter sizes are from 1-6, In the wild grasshopper mice produce an average of three litters per year and up to 6 in a lab environment. The male and female rear their young together.
Lifespan: Approximately three years.
Notes: Because of its territorial nature the grasshopper mouse is sparsely populated over a wide area and adapts well to varied climates. Despite their ferocious nature, grasshopper mice are preyed upon by owls, coyotes, snakes and other predators and are easily displaced by human populations.
- McCarty, Richard (1978), "Onychomys Leucogaster", Mammalian Species 87: 1–6 (--or--, http://www.science.smith.edu/msi/pdf/i0076-3519-087-01-0001.pdf, retrieved (October 4, 2012)
- "Onychomys Leucogaster", NatureServe, (2003), http://www.natureserve.org, retrieved (October 16, 2012)
- Minnesota Department of Natural Resources, Lemmings, Mice Rats and Voles, http://www.dnr.state.mn.us/mammals/mice_voles_rats/index.html, retrieved (October 16, 2012)
- The Worsley School ((2001)), Carnivorous Mice, http://www.worsleyschool.net/science/files/grasshopper/mouse.html, retrieved (October 16, 2012)