PREBLE’S MEADOW JUMPING MOUSE } Zapus hudsonius preblei
DESCRIPTION: The Preble's jumping mouse has a distinct dark, broad stripe on its back running from head to tail, bordered on either side by gray to orange-brown fur. The fur on its underside is white and much finer in texture than the coarse hair on its back. The total length of an adult Preble's is approximately eight to 10 inches, with more than 60 percent of its length in its tail.
HABITAT: Meadow jumping mice prefer low undergrowth consisting of grasses and forbs in open wet meadows and riparian corridors; they also favor lowlands with medium to high moisture over drier uplands and are most common in lush vegetation along watercourses or in herbaceous understories in wooded areas.
RANGE: Records for the Preble's meadow jumping mouse define a range along portions of the North Platte, South Platte, and Arkansas river basins. In Wyoming, the mice have recently been found at more than two dozen sites and in four of the five counties believed to comprise the historical range at the time of listing: Albany, Laramie, Platte, and Converse counties. In Colorado, they have been found in portions of Boulder, Douglas, El Paso, Elbert, Jefferson, Larimer, and Weld counties.
MIGRATION: Rather than migrating, the Preble's is a true hibernator, usually for seven or eight months between September or October and May.
BREEDING: Meadow jumping mice usually have two litters per year, but there are records of three. An average of five young are born per litter, but the size of a litter can range from two to eight.
LIFE CYCLE: The Preble's is long-lived for a small mammal, especially in comparison with many species of mice and voles that seldom live a full year. Seven individuals captured in Boulder County, Colorado as adults were still alive two years later, having attained at least three years of age. But the Preble's annual survival rate is low, and lower over the summer than over the winter.
FEEDING: The Preble's diet shifts seasonally. After emerging from hibernation, the mouse eats primarily insects and fungus; its diet then shifts to fungus, moss, and pollen during mid-summer, with insects again added in September.
THREATS: Habitat loss and degradation caused by agricultural, residential, commercial, and industrial development have shrunk or eliminated populations of the Preble’s meadow jumping mouse. Urban development has been the primary driver of habitat loss in Colorado, and the conversion of native riparian ecosystems to commercial croplands and grazed rangelands has been the primary driver in Wyoming.
POPULATION TREND: A scarcity of historical demographic data makes population trends difficult to determine, though it is known that the Preble's no longer inhabits a number of sites where it was found in the past (including Adams, Arapahoe and Denver counties in Colorado). The species is clearly in decline throughout large portions of its range.