Tiny mouse - if it exists - is weighty issue

CHUGWATER, Wyo. - Amy and Steve LeSatz want to be able to teach their clients the finer points of riding and roping, without having to trailer their animals 25 miles to the nearest public indoor arena whenever the weather turns miserable.

But the LeSatzes aren't able to build their own riding arena. The only decent site on their property in southeastern Wyoming lies within 300 feet of Chugwater Creek, and building there is far too expensive because of Endangered Species Act restrictions intended to protect the Preble's meadow jumping mouse.

"The mouse that doesn't exist," Amy LeSatz noted dryly.

After six years of regulations and restrictions that have cost builders, local governments and landowners on the western fringe of the Great Plains as much as $100-million by some estimates, new research suggests the Preble's mouse in fact never existed. It instead seems to be genetically identical to one of its cousins, the Bear Lodge meadow jumping mouse, considered common enough not to need protection.

The new research could lead to loss of the Preble's "threatened" status and removal from Endangered Species Act protection. The U.S. Fish and Wildlife Service plans to decide that question in December.

"We're trying to be deliberate in our work, trying to get the best science we can and review of the science we do have, in making this decision. Because we know it is very important and serious to a lot of people," said Ralph Morgenweck, regional director of the U.S. Fish and Wildlife Service in Denver. "But I would also say it is a lot more complicated than what it appears to be."

Far from closing the book on the Preble's mouse, the research by the Denver Museum of Nature and Science has opened a new volume of questions - including what to do about affected landowners, whether the Bear Lodge mouse also needs protection and whether the Endangered Species Act itself needs changes.

"If we've shown that the mouse doesn't exist, what happens to all that has been set aside? Because that's been a huge economic burden," said Brian Garber, assistant director of governmental relations for the Colorado Contractors Association.

Meadow jumping mice live near streams, and nearly 31,000 acres along streams in Colorado and Wyoming have been designated critical mouse habitat. That includes large parts of the Colorado Front Range, which over the past several years has been rapidly developed with strip malls and housing subdivisions.

Front Range developers and local governments have had to set aside a lot of land to protect the mouse, though if protections are lifted, that does not mean all that land can be developed. Subdivisions, for example, have roads, sewers, water lines and other infrastructure designed for a certain number of homes. In many cases, adding more homes is not feasible.

But developers would like to see restrictions, which can be both expensive and annoying, ended for future development. In one Colorado Springs, Colo., subdivision, for example, the restrictions include a requirement that cats be kept on leashes.

On top of that, the mouse also has blocked the construction of reservoirs amid a five-year drought in the Rocky Mountains.

"The bottom line is, it has been a wonderful tool for environmental groups to try to stop things," said Kent Holsinger, attorney for Coloradans for Water Conservation and Development, which has asked the Fish and Wildlife Service to remove the mouse from federal protection.

Indeed, environmental groups are now calling for Endangered Species Act protection for the Bear Lodge mouse. They say that subspecies - which had been thought to be limited to the Black Hills of South Dakota and Wyoming but now appears to exist as far south as Colorado Springs - suffers from the same habitat degradation.

The Preble's mouse was established as a distinct subspecies by a study 50 years ago that was cited in the 1998 decision to declare it threatened.

The man who did the 1954 study, Philip Krutzsch, now a professor emeritus with the University of Arizona, had examined the skulls of three mice and the skins of 11 others. It was an acceptable level of scrutiny at the time but "an extremely weak inference by today's standards," said Rob Roy Ramey II, curator at the Denver Museum of Nature and Science and project leader on the new DNA research that overturns Krutzsch's conclusion.

Ramey and his colleagues analyzed mitochondrial DNA, the cell's genetic code, from several of the 12 subspecies of meadow jumping mice, which range from the Pacific to Atlantic and as far south as Georgia. They also repeated Krutzsch's skeleton measurements, using more specimens - mainly from university and museum collections - and more accurate tools. They concluded that the Preble's mouse is actually a Bear Lodge meadow jumping mouse, not a separate subspecies.

But, inadequate as it may have been, Krutzsch's old study was the best science that had been done up until the listing of the Preble's mouse. The Endangered Species Act only requires that species protection be based on the best available science - not the best possible science.

The LeSatzes, meanwhile, say they hope they will at last be able to build their riding arena. "A tiny little mouse comes in and changes your whole perspective," Amy LeSatz said. "I've had more of an education in endangered species than I've ever wanted."

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