Office of External Affairs
Mountain-Prairie Region


U.S. Fish and Wildlife Service
Mountain-Prairie Region
134 Union Boulevard
Lakewood, Colorado 80228

 July 9, 2008


Contact: Diane Katzenberger 303.236.4578 


U.S. Fish and Wildlife Service Revises the Endangered Species Act Status

of the Preble’s Meadow Jumping Mouse


The U.S. Fish and Wildlife Service today announced the removal of Endangered Species Act (Act) protection for Preble’s meadow jumping mouse populations in Wyoming. The Service also amended the listing for Preble’s to indicate the subspecies remains threatened in the Colorado portion of its range.  This determination is based on a better understanding of the distribution of and threats to Preble’s meadow jumping mouse populations in Wyoming and Colorado.


Today’s decision was made following an analysis of current scientific research that found Preble’s mouse populations in Wyoming no longer meet the criteria for being a threatened or endangered species. The Service has also determined that the best scientific and commercial information available supports the conclusion that Preble’s meadow jumping mouse is a valid subspecies eligible for protection under the Act. Preble’s geographic isolation from other subspecies of meadow jumping mice led it to develop considerable genetic differences from those other subspecies.  The available data suggest that Preble’s meets or exceeds numerous, widely accepted subspecies definitions.


“This action will allow us to more precisely focus the protections of the Act specifically where these protections are needed,” said Steve Guertin, the Service’s Regional Director for the Mountain-Prairie Region. “The Service will continue to work with all of our partners to implement conservation actions that will benefit the mouse and help us achieve healthy populations across its entire range.”


This new distributional data and a better understanding of threats to the mouse have altered the Service’s understanding of the subspecies’ status in the Wyoming portion of its range.  At the time it was added to the federal list of threatened and endangered species, the Preble’s meadow jumping mouse was known only to occur in a few sites in Wyoming.  Since then, additional distributional data have verified that Preble’s populations occur in and appear secure throughout the North Platte River basin in Wyoming. 


Land use across Preble’s habitat in Wyoming is dominated by agriculture, mostly haying and grazing.  Continuation of these long-standing activities does not appear to pose a threat to existing Preble’s populations.  In addition, there is no indication that these agricultural practices are likely to change in the foreseeable future in ways that would affect Preble’s populations.  A low projected human population growth rate is predicted for the four Wyoming counties (Albany, Laramie, Platte, and Converse) that support Preble’s populations.  Consequently, few of the development-related impacts occurring in Colorado’s portion of the Front Range urban corridor are expected to impact Preble’s populations in Wyoming. 


In Colorado, increased live trapping efforts have identified some additional sites occupied by Preble’s; however, since listing, more than 80 percent of Colorado trapping efforts targeting Preble’s have failed to capture any individuals of the species.  These results suggest that the subspecies is rare or extirpated from many portions of its historical range in Colorado.


In much of the Preble’s range in Colorado, development activities have severely altered or destroyed its habitat.  Given current and projected human population increases and corresponding increases in urban and rural development, the ongoing loss and modification of riparian habitat is expected to continue in much of the Preble’s range in Colorado. The Service believes that the loss of Preble’s populations in Colorado as a result of habitat loss and modification would meaningfully decrease the ability to conserve the subspecies.  Without the protection of the Endangered Species Act, most of the remaining habitat will be lost or altered within the foreseeable future.  Based on its importance to the conservation of the Preble’s meadow jumping mouse, the Service has determined that the Colorado portion of the range constitutes a significant portion of the mouse’s range where it should remain protected.


Preble’s populations have been recently documented in portions of Boulder, Douglas, El Paso, Elbert, Jefferson, Larimer, and Weld counties in Colorado.


The Preble’s meadow jumping mouse is a small mammal with a long tail, large hind feet, and long hind legs.  Total length of an adult is approximately 7 to 10 inches, with the tail comprising approximately 60 percent of that length.  To evade predators, the mouse can jump up to three feet. 


The Preble's meadow jumping mouse is found along the foothills in southeastern Wyoming southward along the eastern edge of the Front Range of Colorado to Colorado Springs in El Paso County, Colorado.  It inhabits well-developed plains riparian vegetation with relatively undisturbed grassland communities and a nearby water source.  It has been found to use uplands at least as far out as 100 meters beyond the 100-year flood plain. Habitat alteration, degradation, loss, and fragmentation resulting from urban development, flood control, water development and other human land uses have adversely impacted Preble’s populations.


Today’s finding and other materials are available on the Service’s web site at:


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