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Know the West

Is It or Isn’t It (Just Another Mouse)?

Why science alone will not settle the West’s endangered species dilemmas


On a 90-degree day in early June, Rob Roy Ramey II hikes up a steep ridge in Boulder Canyon toward a spot overlooking a golden eagle’s nest. The conservation biologist has volunteered to keep tabs on a hatchling for the Colorado Division of Wildlife.

A compact man with sapphire eyes and a tanned face, Ramey thrives on fieldwork. "I’ve risked my life for endangered species," he says. He’s shot tranquilizer darts at elephants in Zimbabwe, led posses of bewildered locals on harebrained plots to herd Argali sheep in Mongolia, and nearly crashed in a helicopter while studying bighorn sheep in Death Valley.

As he walks, Ramey pontificates — about the importance of getting out into the wild, his critics, and the problems he sees with the Endangered Species Act. At times, his brain seems to spit out ideas faster than his tongue, or lungs, can keep up. Halfway up the climb he stops, not from fatigue, but because he needs to catch his breath after making an especially emphatic point.

At the top of the ridge, Ramey pulls a spotting scope from his well-worn backpack and focuses the viewfinder on the eagle’s nest. "Oh, look! Mom’s feeding junior," he says.

Glassing the eaglet, Ramey acts like a father watching his child’s first steps. But Ramey is careful not to fall into the role of an overly protective parent, and that resistance has won him few friends in the environmental community.

Just up the canyon from here lies Security Risk Crag, one of several rock-climbing areas the U.S. Forest Service’s Boulder Ranger District closes off each spring to protect eagles’ nests. Ramey supports the policy, but when climbers questioned whether the nest at Security Risk was in fact used by eagles, he responded with the mantra that has guided his career: "Show me the data."

Ramey rappelled into the nest and analyzed its contents. He found no evidence that eagles had ever laid eggs in the nest — he suspects it’s used by ravens — and he backed a movement to keep the crag open year-round. So far, the District’s policy hasn’t changed, but Ramey’s actions earned him scorn from some Boulder environmentalists. "Some people didn’t want to accept the facts," he sighs.

The eagle hullabaloo symbolizes the larger criticisms Ramey has lobbed at the U.S. Fish and Wildlife Service’s efforts to protect threatened species. Too often, he says, conservation decisions are based on hypothetical threats or overly cautious assumptions, rather than hard facts.

As evidence, Ramey points to the Preble’s meadow jumping mouse, a creature found only in streamside areas along Colorado’s Front Range. The 3-inch-long mouse has powerful, elongated back legs and clown-sized hind feet that can propel it three feet in a single hop. To evade predators, the mouse can jump like a kangaroo, up to 18 inches high, using its 6-inch-long, whip-like tail as a rudder to switch directions in mid-air. But the little acrobat’s most famous feat is its leap onto the Endangered Species list, a move that has hindered the march of bulldozers along the base of the Rocky Mountains.

One of 12 subspecies of meadow jumping mouse (Zapus hudsonius), the Preble’s mouse was first described in Colorado by naturalist Edward A. Preble in 1899. Nearly a century later, in May 1998, the U.S. Fish and Wildlife Service listed the mouse as threatened and designated 31,222 acres of critical habitat. The listing placed new restrictions on development in moist meadows and streamside areas from Colorado Springs to Laramie, raising the ire of developers and some residents, who complained that, in the words of one letter-writer, the government was putting a disease-carrying rodent ahead of the rights of landowners. Meanwhile, environmentalists rejoiced: The little mouse had given them a new weapon in their drive to limit development in Colorado’s growing metro areas.

Enter Ramey, who, in 2002, got to digging through the scientific literature after a colleague suggested they collaborate on a Preble’s mouse project. Ramey found that the 1954 monograph that classified the Preble’s mouse as a distinct subspecies, had — like many such distinctions of its day — been based almost entirely on the critter’s physical characteristics. Philip Krutzsch, a professor emeritus at the University of Arizona, had made the designation based on coat color and skull measurements – and he’d done so using just a handful of mice. "He’d only looked at four adults and seven juvenile specimens. Juveniles have tons of variation in their coat color," says Ramey, who at the time worked at the Denver Museum of Nature and Science.

With so few specimens, it was possible that the differences Krutzsch had used to split the Preble’s mouse into a new subspecies were just an artifact of his small sample size. "I said, ‘Aha! This is the question to ask: Is this mouse really distinct?’ " says Ramey.

What happened next threw Ramey smack into the middle of one of the Endangered Species Act’s ugliest quagmires. On the surface, it looks like a simple dispute between "lumpers" — biologists who pack varying plants or animals into a single species or subspecies — and "splitters" — those who see such variations as reason to divide wildlife into different classifications. But the debate runs much deeper than science, touching on issues that involve philosophy as much as science. One central question: As long as the government possesses only limited funds to float an endangered species ark, how should it decide which passengers to allow onboard?

The saga began in August 2002, when Ramey proposed to test whether the Preble’s mouse truly qualified as a unique subspecies. The idea elicited a lukewarm response from the Fish and Wildlife Service, but in December, Ramey received a letter from the governor of Wyoming informing him that the state would fund his study. Wyoming had been a reluctant partner in Preble’s mouse protection, and state officials jumped at the chance to poke holes in the designation. Eventually, the Fish and Wildlife Service, along with the Denver Museum of Nature and Science, also kicked in money for the study.

Before he began, Ramey laid out the criteria he would use to determine whether Preble’s qualified as a subspecies. He would look for distinctness in its physical traits, in its ecology and in its genes. The mouse need not turn up uniqueness in all of these areas, Ramey said, but it should prove distinct in the majority of them. One by one, the team pitched these criteria to the mouse. And one by one, the mouse began to miss.

Ramey’s colleague, Lance Carpenter, measured the skulls of museum specimens to test Krutzsch’s assertion that the Preble’s mouse skulls were smaller than those of other meadow jumping mice. Carpenter measured nine characteristics of the Preble’s skulls, and found that they were smaller in only one. The morphological differences noted in Krutzsch’s monograph were merely "unsupported opinion," Ramey would write in his report. Strike one.

Likewise, when Ramey’s team scanned the scientific literature for evidence of ecological differences between the Preble’s mouse and other nearby subspecies, they found none. Ramey argued that if, during the 100-plus years the mouse had been classified as a subspecies, no one had published evidence that the mouse possessed unique ecological or adaptive traits, it was reasonable to conclude that they didn’t exist. Strike two.

Finally came the genetic work. Genetic testing didn’t exist in Krutzsch’s day, but by the time Ramey met the mouse, scientists had developed high-tech tools for peering into DNA and detecting even minute genetic differences. This has become the gold standard for determining whether populations are distinct.

Ramey’s team compared DNA from the Preble’s mouse to that of several nearby jumping mouse subspecies. The researchers examined two types of DNA — one found within the nucleus of cells, the other from organelles called mitochondria, which are passed from mothers to their offspring. Mitochondrial DNA evolves more quickly than nuclear DNA, so if the Preble’s mouse was starting to evolve separately from other meadow jumping mice, this shift would be expected to turn up in the mitochondrial DNA first.

But the Preble’s mitochondrial DNA sequences also turned up in the Bear Lodge meadow jumping mouse, a subspecies found in Wyoming, North Dakota, South Dakota and Montana. The nuclear DNA showed only small differences between the Preble’s mouse and the Bear Lodge mouse, the kind of variation that Ramey says you would expect to find in any normal population of a single species.

With three strikes against it, Ramey concluded that the Preble’s mouse was simply a population of the Bear Lodge meadow jumping mouse. He recommended that the two be lumped together as one subspecies.

When Ramey went public with his study in December of 2003, the crowd on both sides of the ballpark went berserk. The state of Wyoming, which had funded Ramey’s work, wasted no time filing a petition to remove the Preble’s mouse from the threatened species list. A coalition of builders, businesspeople and agricultural interests calling itself Coloradoans for Water Conservation and Development co-signed the petition. The Fish and Wildlife Service estimates that the Preble’s listing alone costs developers and landowners as much as $18 million a year; developers put the cost much higher.

Politicians seized on Ramey’s work as proof that the Endangered Species Act was protecting a mouse that had never existed in the first place. Senator Wayne Allard, R-Colo., called for the creature’s immediate delisting. House Representative Tom Tancredo, R-Colo., introduced a bill that would have delisted the Preble’s mouse and forbidden it from receiving any future Endangered Species Act protection.

Meanwhile, environmental groups pointed to delisting efforts as evidence of political tampering with science — accusations that grew more shrill when Ramey signed on as a consultant for the Interior Department, and testified before Congress in favor of Endangered Species Act reform. "If the Bush Administration really cared about good science, as they are so fond of claiming, and if they had any respect at all for the law, their decision would be a no-brainer," the Center for Native Ecosystems, a Denver-based environmental group, wrote on its Critterthink blog. "Alas, we all know this was never about the science or the law. This is about politics and money."

When the Fish and Wildlife Service asked 14 scientists to review Ramey’s report and verify his conclusions, their results did little to quell the debate.

Geneticist Keith Crandall of Brigham Young University was thoroughly convinced by Ramey’s argument, calling his conclusion "robust" and "strongly supported by all forms of data examined." Others, such as Gary White of Colorado State University, felt that Ramey’s work was insufficient to overturn a long-standing subspecies classification. Ramey’s conclusions, White wrote in his review, "are an example of basic statistical misinterpretation."

What everyone did seem to agree on, however, was the need for a more definitive answer. So the Fish and Wildlife Service commissioned U.S. Geological Survey geneticist Tim King to conduct an independent genetic analysis of the Preble’s and several other meadow jumping mouse subspecies.

A quiet man who shuns the limelight, King works at the Leetown Science Center in Kearneysville, W. Va. He conducted a genetic analysis of Atlantic salmon that was cited in the decision to place the fish on the endangered species list. He was chosen in part because he had never worked with the Preble’s mouse, and was not a stakeholder in the debate.

Like Ramey, King examined snippets of DNA from various populations of Preble’s and four neighboring jumping mouse subspecies. But where Ramey tested a few individuals from many different populations, King looked at DNA from many individuals from a smaller number of populations. Each approach has its dangers. Collect DNA from too few individuals from a given population, and you may not detect the true patterns of variation within that group. Collecting many samples from each population solves this problem, but unless you sample every population, you still may miss differences that exist in these groups. Ideally, the two sampling methods would be combined, but in the real world, funding and time constraints can make this impossible.

King tested two regions of mitochondrial DNA and 21 regions of nuclear DNA from each individual. Unlike Ramey, King saw clear distinctions between the Preble’s mouse and the other four subspecies. In a peer-reviewed report sent to the Fish and Wildlife Service in January 2006, King argued that the variations suggested that the Preble’s mouse had mutated and diverged from other meadow jumping mice.

King pointed out that Krutzsch split the Preble’s mouse from other subspecies based not only on its physical features, but also on its geographic isolation. A gap of 60 miles or more separates the Preble’s mouse from the nearest Bear Lodge mouse populations, and King says that the differences that have evolved in the Preble’s DNA show that it has been isolated from other subspecies for thousands of years.

To King, the implications were clear: The Preble’s mouse was headed down its own, unique evolutionary path. "The data are unequivocal," he said.

Two studies. Two opposing conclusions. While it might smell of dirty politics, such conflicts are not unheard of in taxonomy. The problem arises because scientists can’t agree on a definition of species, let alone subspecies, says Susan Haig, a geneticist at the U.S. Geological Survey’s Forest and Rangeland Ecosystem Science Center in Corvallis, Ore. Taxonomists have spent entire meetings, even whole careers, debating species concepts without ever reaching an agreement. "It’s not like scientists are space cadets," Haig says. "It’s the fact that technology changes, our view of the world changes, we learn more."

At issue are questions like: How unique must a population be to warrant status as a subspecies? Is geographic isolation enough, or should genetic differences or physical traits like size or pelt color be required too? Which traits should carry the most weight? How much intermixing can go on between subspecies without jeopardizing their status? Science has yet to reach a consensus on these issues, says Haig. "Someone puts out a definition, and people pick it apart and refine it, and then other people pick it apart and keep refining it."

The debate that once took place at obscure conferences has spilled into the public arena, because under the Endangered Species Act, subspecies receive as much protection as full species. In fact, 20 percent of all the wildlife species protected by the act are actually subspecies. Deciding where to draw the lines between subspecies is critical, but the Fish and Wildlife Service’s guidelines are open to interpretation.

In the case of the mouse, Ramey chose one definition and King chose another. Stakeholders on both sides of the debate claimed the science lay in their court. And to some extent, both sides were right.

The debate roiled for nearly three years, with neither side giving an inch. "King has what I consider a very, very low bar," said Ramey. He argued that the genetic differences King found between Preble’s and the Bear Lodge mouse were not biologically meaningful, because they were found in "neutral markers," which don’t encode genes. "Most people would call this junk DNA," Ramey said, adding that he’d found similar levels of genetic variation between populations of bighorn sheep on opposite sides of Interstate 40 in California. "The sheep are literally staring across the highway at each other," he said.

But King’s backers argued that Ramey failed to gather enough data to test his criteria, which they called unduly strict. "The King study literally quadrupled the amount of genetic data and found clear separations between all five subspecies," said Sylvia Fallon, a conservation genetics fellow at the Natural Resources Defense Council in Washington, D.C. "Ramey and King aren’t arguing over where to draw the line. Ramey’s study failed to find any lines to draw because he didn’t have enough information."

Ramey’s critics also questioned his interpretation of his results. "Ramey set a very, very high bar," said Wayne Spencer, a biologist at the Conservation Biology Institute in San Diego, who, at the request of the Fish and Wildlife Service, reviewed both papers. "The genetic tests (Ramey) used don’t even show differences between valid species, like between polar bears versus grizzlies," he said.

King added fuel to the fire this June, when he submitted a paper for publication in the journal Molecular Ecology revealing that he tried, and failed, to replicate some of Ramey’s genetic data. In dispute are seven Bear Lodge mouse museum specimens that, in Ramey’s study, turned up mitochondrial DNA sequences also found in Preble’s mouse specimens. King’s work showed that none of these seven specimens contained the Preble’s sequences. What’s more, King turned up discrepancies in more than a dozen nuclear DNA sequences from Ramey’s museum specimens, which, King said, suggested a systematic error in Ramey’s methods.

Ramey said he was looking into the samples in question and will file a correction if his original data were wrong. But he argued that the dispute was not about whose dataset was most robust, but about how to interpret the data. "Tim can find these statistically different things between populations, but how biologically significant are they? If you look at species and subspecies through the end of a pipette you can lose the forest for the trees." In fact, neither Ramey nor King has ever seen a live Preble’s meadow jumping mouse.

Whose conclusions were correct? Both of them, said BYU’s Keith Crandall, who, with funding from Wyoming, combined and analyzed both datasets. Though Crandall came down on Ramey’s side, he acknowledged that King’s arguments had merit. "They both collected data relevant to the questions they posed and both addressed them in ways that they thought were reasonable and came to opposite conclusions," Crandall said. "How do you resolve that? You don’t. You argue until the cows come home."

But the Fish and Wildlife Service doesn’t have that kind of time. By law, the agency must respond to Wyoming’s petition to delist the Preble’s mouse by the first week of August. The agency needs an answer now. So with the clock ticking and the entire Front Range looking on, the agency contracted the Portland-based Sustainable Ecosystems Institute to convene a panel of scientists to weigh the scientific evidence.

The panel meets in early July, in a small conference room at Colorado State University in Fort Collins. A courtroom-like aura hangs in the room. The three panelists — Brian Arbogast of Humboldt State University, John Dumbacher from the California Academy of Sciences and Scott Steppan of Florida State University — sit behind a table at the front of the room. Given their distinct morphology (bald head), adaptations (identical Macintosh laptops) and behavior (a tendency to ask probing questions) the panelists themselves might qualify as a distinct subspecies under some definitions.

The audience includes scientists from several universities and the Fish and Wildlife Service, employees of a Colorado Springs utility, representatives from numerous environmental groups, a landowner who claims the Preble’s mouse has prevented him from developing his five-acre parcel on Monument Lake, and representatives from the offices of several politicians, including a well-coiffed woman who will type messages on her BlackBerry throughout much of the meeting.

The mouse itself is absent, but Craig Hansen, a flamboyant young biologist who has spent hours tagging and tracking the little creatures, passes around his newly bound master’s thesis like a new father with his firstborn’s baby book. "Just look at his feet — they’re huge!" Hansen exclaims, pointing at a photo. "These mice are so cool!"

Ramey arrives dressed to perform in a sporty suit and a tie adorned with elephants and lions. He sits restively in the front row next to another suit — Wyoming’s assistant attorney general. "I want to pursue truth and I’m ready to do battle," Ramey says.

King, perhaps the tallest man in the room, is also the most reserved. Casually attired in jeans, and clearly determined to keep the focus on his research and not himself, he settles in an empty row on the opposite side of the room from Ramey and further back.

Steven Courtney, vice president of Sustainable Ecosystems Institute, opens the meeting with a quote from Niccolò Machiavelli. "A hypothesis is always more believable than the truth, for it has been tailored to resemble our ideas of truth, whereas the truth is just its own clumsy self." The panel’s mission, Courtney says, is to seek the clumsy truth about the Preble’s mouse.

Panelist John Dumbacher gives an overview of the scientific controversy. He explains that rather than trying to agree on a definition of a subspecies, the panel will compile an array of definitions and assess the same three lines of evidence that Ramey first pitched at the Preble’s mouse — its physical traits, ecology and genetics — to determine where the mouse falls within each definition.

The panelists quickly delve into the mouse’s physical characteristics, and Dumbacher calls Ramey up to the front to talk about his study. Before he begins, Ramey walks over and extends a hand to King. It is the first time the two have met. "I want to offer a personal apology to you for comments that ended up in the press," Ramey says, no doubt referring to his statement to the Rocky Mountain News that "Tim King’s station in life seems to be to do scientific colonoscopies." King nods, but declines to engage Ramey. Then it is Ramey’s turn to take a drubbing. Sacha Vignieri, the lead author on a vigorous rebuttal of Ramey’s work published in Animal Conservation, rings in on the speaker phone from the University of Sussex in the United Kingdom and tells the panel that Ramey’s team tested only one of Krutzsch’s original six skull characteristics and none of his five pelt traits.

James Patton, curator at the University of California, Berkeley, Museum of Vertebrate Zoology, echoes her concerns. If someone wants to overturn an existing taxon, then at a bare minimum, "You need to go back and evaluate the original criteria used to name that taxon," Patton tells the panel via speaker phone. "I don’t think that has been done."

Ramey passionately defends his choice of traits. At times he speaks so breathlessly that the court reporter hired to transcribe the meeting asks him to slow down. He tells the panel that his team eliminated characteristics that were subjective, like pelt color, and focused on traits they could measure.

The panel quizzes both Ramey and King about their genetic results. Ramey insists that the DNA put the Preble’s mouse on a tiny, unimportant twig on the mouse family tree. King responds that Ramey’s strict criteria would only find differences between full-blown species, not the more subtle differences between subspecies. "I don’t want to know if it’s a species. I want to know if it’s a subspecies," King says, never raising his voice. At times, the court reporter cranes her head forward to hear King, and more than once, a panelist inches the microphone closer to him so all can hear.

Questions about the mouse’s ecological traits evoke heated debate. Ramey says that not a single published study has found evidence that the mouse possesses unique ecological or adaptive traits, but Dumbacher appears skeptical. "Not finding a difference is different from finding that there is no difference," Dumbacher says.

Vignieri, on the speaker phone, argues that such differences are likely to exist, because the Preble’s subspecies lives only near water. "They’re clearly specialized to riparian habitat. They might not specialize on a particular fungi, but they do specialize." It’s an important point, because if the mouse is limited to a specific habitat, it cannot spread just anywhere and could feel the loss of habitat more acutely than it would if it could simply pick up and move.

Crandall, who sports a gray suit and a Marlboro Man mustache, tells the panel that the only sure way to determine whether the Preble’s mouse is ecologically unique would be to put a Preble’s mouse in a Bear Lodge population. If the Preble’s mouse not only survives, but also plays the same role in the local ecosystem, the two mice are obviously interchangeable. However, says Crandall, it’s an experiment that clearly can’t be done with an endangered species.

The verbal pingpong goes on like this for two days. At times, Ramey seems grossly outnumbered, but he refuses to back down. For every argument made against him, Ramey stands ready with an explanation.

But when panelists dig in to the disputed DNA data, Ramey seems to shut down. When asked technical questions about the discrepancies between his and King’s DNA results, Ramey repeatedly answers, "You’ll have to ask Hsiu-Ping (Liu)" — his colleague, a faculty member at the University of Denver, who did the DNA analysis. He gives panelists Liu’s phone number, but efforts to reach her initially fail.

As the panel winds down, both sides seem ready to declare victory. If a consensus has emerged, it is that good scientists must sometimes agree to disagree. Dumbacher wraps up the discussion by commending both Ramey and King. "I’d hate for my own research to have to undergo this kind of scrutiny," he tells them. Courtney closes the panel by saying, "There is no need to identify a winner here in personal terms. The winner is the scientific process."

When the panel releases its report in late July, the conclusion proves surprisingly unequivocal: The Preble’s mouse is a distinct subspecies. "The available data are broadly consistent with the current taxonomic status of (the Preble’s mouse)," the report says. "No evidence has been presented that critically challenges that status." Even more stunning, the panelists have found that some of Ramey’s DNA samples show signs of contamination, which could account for the discrepancies between his study and King’s.

But even if Ramey’s data crumbled under scrutiny, his philosophical stand did not. "This doesn’t change anything," he says. The latest verdict, like all other decisions about subspecies designations, will remain arbitrary until scientists can agree on a definition of subspecies, he says. "What’s your listable entity? That’s the real question."

And Ramey’s philosophical arguments remain. At its core, the Preble’s dispute was never really about whether the mouse is a species or subspecies. Strip away the dueling datasets and clunky jargon and the dispute comes down to a philosophical question about what the Endangered Species Act should protect. When King and Ramey step back from the scientific debate, they both acknowledge this.

"It doesn’t matter to me whether it’s a subspecies or a distinct population segment," says King. "Any group within a taxa that appears to be reproductively isolated and heading down a different evolutionary trajectory from another group warrants conservation and attention, or at least consideration."

Not so fast, says Ramey. He argues that there’s a danger in overzealously applying caution to endangered species decisions. "If you set the bar too low, you completely dilute your effectiveness," he says. "We can make a conscious decision as a society that we want to give local populations of mice that have low levels of genetic differences the full protection of the Endangered Species Act. But ask yourself what it’s going to mean for the really unique things that you now don’t have the money to protect."

A priority system for applying the Endangered Species Act exists, but a 1988 General Accounting Office report criticized the Fish and Wildlife Service for not adhering to it. A recent study showed that things have hardly improved since then, with species that occur in urban areas receiving disproportionate funding at the expense of island species facing more urgent threats.

The genetic research, which many people have looked to for answers, only seems to add to the arbitrary approach. The Fish and Wildlife Service provides no guidelines on how genetic data should be used to make listing decisions. When Sylvia Fallon with the Natural Resources Defense Council recently reviewed more than 40 listing decisions, she discovered that the amount and type of genetic data that informed these decisions were all over the map. Studies that had used large amounts of genetic information tended to result in decisions that granted Endangered Species Act protection, while those that used less genetic data were more likely to end in verdicts that declined protection.

Ramey argues it’s time to change the way the Endangered Species Act is used. As it stands, the law is wielded far too often as a weapon against development at the expense of species that truly need protection, he says. Society shouldn’t need to find an endangered species in an area to save it: "If you want some open spaces that have lots of plants and animals in them, ultimately that’s the value, so let’s use that."

Other options do exist for protecting the habitat of the Preble’s mouse. Some Front Range communities collect funds to buy and protect open space, and private groups might also step in to pay for riparian habitat protection. But these strategies lack the teeth of the Endangered Species Act, and they cannot protect whole swaths at once.

And environmentalists counter that, until the laws change, the Endangered Species Act is the best tool they have for protecting ecosystems, something that not only benefits listed species, but everything else that uses an ecosystem, including humans. "This mouse is found only along healthy streamsides, so protecting it also means protecting our drinking water," says Erin Robertson, a staff biologist at the Center for Native Ecosystems. She acknowledges that reasons for protecting the Preble’s mouse extend beyond the little critter itself. The Preble’s mouse occurs on a habitat that’s quickly being developed: "That’s the bang for the buck on the mouse," she says.

The Fish and Wildlife Service will announce its decision on the delisting petition any day now — potentially before this issue arrives in your mailbox. But regardless of the outcome, the story doesn’t end here. While the panel’s report slams the door on the taxonomic arguments in the current delisting petition, those pushing to delist have a plan B at the ready. In March, Wyoming Attorney General Patrick Crank and his counterpart from Colorado, John Suthers, wrote to Fish and Wildlife Service Director Dale Hall, arguing that, subspecies or not, the mouse is more abundant than scientists first thought. "The Preble’s mouse is not threatened," they wrote, "it was just not well trapped in 1998" when it was given Endangered Species Act protection.

No doubt, if the Fish and Wildlife Service denies Wyoming’s existing petition to delist the mouse, another petition will be close behind.

If that happens, both sides of the debate will again look to science for support. But in the end, science may represent more of a trap than a solution. Science can answer questions about this mouse’s physical and genetic traits and its role in the ecosystem, but it cannot make the final call. The question of whether the Preble’s mouse —and the vanishing streamside habitat along Colorado’s Front Range — deserve protection is one that society must answer for itself.

Christie Aschwanden is an award-winning freelance writer in Cedaredge, Colorado. Her work has appeared in more than 30 publications, including National Wildlife, New Scientist and Skiing.

The following sidebar article accompanies this story:

A few scientific definitions - Terms commonly used in endangered species discussions – species, subspecies and distinct population segment – are explained