Of Mice and Men

What the battle to save an obscure rodent says about the cost of front range growth.

Somewhere beneath the tall grasses of Rocky Flats, not far from the small streams that wind through the buffer zone surrounding the former nuclear-weapons plant, a Preble's meadow jumping mouse is taking a well-deserved nap. Its fate is being decided elsewhere.

The mouse--which weighs less than an ounce, sports a six-inch tail that accounts for more than half its length and boasts oversized hind legs suitable for leaping several feet--hibernates from October until early May. You would, too, if you had the Preble's problems. During the summer months, the mouse scampers about at night, dodging predators, foraging for grass seeds, berries and insects, and caring for two or three litters. The final weeks before it descends into its leaf-lined burrow are devoted to a feeding frenzy, building up fat reserves for the winter.

The Preble's work is never done, it seems. Even its seven-month snooze isn't as restful as it once was, what with all the biologists busily studying its behavior, trying to identify its habitat, and plotting next summer's trapping season--a process that has intensified since last March, when the U.S. Fish and Wildlife Service (USFWS) formally proposed listing the Preble's as an endangered species. While the mouse sleeps, its mere presence at Rocky Flats and a handful of other sites in Colorado and Wyoming is shaking up a host of development plans and public works projects.

The mouse has alarmed ranchers, annoyed county commissioners and frustrated open-space planners. It has delayed a $35 million pipeline project in El Paso County and drastically altered a private company's plans to mine gravel at Rocky Flats. It has raised questions about a new highway interchange north of Colorado Springs and a proposed 18,000-acre development in Jefferson County. It has sparked at least three lawsuits filed by environmental groups that have accused the federal government of not doing enough to protect the mouse. And it has cost taxpayers plenty, including a recent $400,000 congressional appropriation to develop a plan to keep the mouse from being an even greater threat to future development.

All this fuss over a critter most people have never seen strikes some observers as absurd. "These little rodents have no place in the ecosystem of any benefit," wrote Wayne Bonham, president of Wyoming's Pole Mountain Cattlemen's Association, in a letter of protest to the USFWS a few weeks ago. "They are of no benefit to the human being. Why spend the taxpayers' money and the general public's time for something that is so meaningless?"

The mouse's defenders, though, say the sudden wave of attention is long overdue; after all, look at what humans have done to the mouse. The Preble's subspecies of jumping mouse is found principally along a narrow band of heavily vegetated rivers, creeks and other drainages--known as riparian corridors--on the east side of the Rockies from Cheyenne to Colorado Springs, an area that's been all but devoured by the past two decades of urban sprawl.

"They like a lot of structure," says mammalogist Carron Meaney. "Not just plain grasses, but a mixture of dense shrubs, coyote willow and overhanging cottonwoods. Unfortunately, the areas they like are also extremely popular with people."

Exact numbers are hard to come by, but those who've studied the mouse believe that massive urban development has devastated the Preble's habitat and reduced its population to a few hundred, scattered among isolated sites in half a dozen Colorado counties and two sites in southern Wyoming. Significantly, the healthiest known colonies are at the U.S. Air Force Academy and Rocky Flats--two federal properties that have been largely insulated from development pressures since the 1950s.

"This is one of the rarest, most imperiled, unprotected small mammals in the United States," says Jasper Carlton, executive director of the Biodiversity Legal Foundation, a Boulder-based nonprofit that sued the USFWS to compel the agency to declare the mouse an endangered-species candidate. "We've concluded that it's more endangered than the black-footed ferret was when they listed it, more endangered than 90 percent of the species that have been listed under the Endangered Species Act. The populations we know of are so small that they're all threatened."

The USFWS has until next spring to decide whether to add the mouse to the endangered species list. The final decision will be made by the agency's new director, Jamie Rappaport Clark. Last year Clark, then an assistant director of ecological services, filed an affidavit in response to the Biodiversity Legal Foundation's lawsuit, declaring that the Preble's jumping mouse "does not face an imminent risk of extinction." This year her agency has announced that the mouse "is in danger of extinction throughout all or a significant portion of its range."

Fish and Wildlife's official ambivalence is indicative of the divided opinion about the mouse in regulatory and scientific circles. Mouse researchers like Meaney say they still don't know enough about the shy, nocturnal creature's behavior, habitat needs and reproductive cycle to accurately gauge its chances for survival, nor can they make reliable projections of the size of a given population based on the few mice that have been trapped at various sites.

"We've had more people out looking for this thing in the last five years than in all its history before that," says Peter Plage, a biologist in the USFWS Colorado field office who's been coordinating the agency's efforts on behalf of the mouse. "But there's a lot we still don't know."

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