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Of Mice and Men: The Endangered Species Act and Preble’s Meadow Jumping Mouse

Photo of mouseScientific debate is often a surrogate for debate over societal values.  A recent example is the controversy over the Preble’s meadow jumping mouse (PMJM), a 20-gram mouse living in riparian areas along the eastern Front Range of Colorado and southern Wyoming.  Consider the following reactions to the proposed delisting of the mouse as a threatened species under the Endangered Species Act (ESA):

“We are confident science is on our side. This mouse has cost the state hundreds of millions of dollars” (a developer on learning that PMJM had been proposed for delisting).

“They are removing protection based on sloppy science and political pressure. Riparian areas in the state will be completely developed” (a conservationist on learning that PMJM had been proposed for delisting).

“There appears to be a substantial disconnect between accepted scientific standards and how science is used in decisions regarding endangered species management. The Endangered Species Act faltered around this one critter. Objective and independent peer review should be sought for proposed listings . . . and delistings” (a scientist testifying before the House Committee on Resources).

As these quotes illustrate, disputants in environmental controversies look to science to legitimize their preexisting value preferences.  But is this an appropriate role for science?  What are the consequences for both science and politics of waging value disputes through science? 

PMJM was listed as a “threatened species” under the ESA in 1998 because of decline in the quality and extent of its habitat.  At that time, its classification as a subspecies of the meadow jumping mouse - based on a 1954 peer reviewed study - was widely accepted by scientists.  However, this classification was challenged in 2004 by a study by Ramey et al. that included morphological analysis of skulls and phylogenetic analysis of a small amount of mtDNA, and that concluded there was no basis for distinguishing PMJM. Immediately following the announcement of these results in the news media, but prior to any peer review, the U.S. Fish and Wildlife Service (FWS), which enforces the ESA, received two petitions to delist the mouse claiming PMJM does not meet the definition of a separate species and therefore was listed in error.

Adding or removing a species from ESA protection must be supported by the “best scientific and commercial data available”.   In response to the petitions to delist FWS asked fourteen scientists with relevant experience to review the Ramey study.  Five supported its findings, though two of these felt the mouse remained imperiled; six were critical of the methods and/or skeptical of the conclusions; and three provided mixed reviews. FWS concluded that the PMJM should be considered for delisting.

What constitutes the “best scientific and commercial data available”?  The term is not defined in the ESA. Legislative history, agency guidelines, and case law have interpreted it to mean that conclusive evidence is not required before listing decisions can be made.  Agencies are directed to consider all of the information (published and unpublished) available and when scientific data are equivocal they are to give the benefit of the doubt to the species.

In this case, arguments about “the best available science” have centered on whether the science in question has been peer reviewed.  Some who generally would like to see fewer species listed under the ESA argue that independent peer review (beyond the required administrative peer review) should be employed before listing decisions are made.   However, the Ramey et al. study had not yet been published in a peer-reviewed journal when it was submitted with the petition to delist. Publication in a peer-reviewed journal is the accepted process for proposing taxonomic changes. 

On the other hand, those who do not feel that the “best available science” standard should require independent peer review (and would generally like to see stronger ESA protections) maintain that the current process for listing species is already sufficiently cumbersome.  The Ecological Society of America fears that requiring independent peer review may unnecessarily lengthen the listing process without providing any substantial benefits.  The American Institute of Biological Sciences points out that, while peer review can identify data limitations or other uncertainties, it cannot resolve them.

Ironically some who are opposed to delisting the PMJM criticize the Ramey et al. study because it was not published in a peer-reviewed journal.  These contradictions and heated arguments over peer review suggest that other issues may underlie the question of whether to delist the PMJM.

This controversy illustrates an all-too-familiar phenomenon described by Dan Sarewitz in his article How science makes environmental controversies worse: “The growth of considerable bodies of scientific knowledge, created especially to resolve political dispute and enable effective decision making, has often been accompanied instead by growing political controversy and gridlock. Science typically lies at the center of the debate, where those who advocate some line of action are likely to claim a scientific justification for their position, while those opposing the action will either invoke scientific uncertainty or competing scientific results to support their opposition… The notion that science is a source of facts and theories about reality that can and should settle disputes and guide political action remains a core operating principle of partisans on both sides of … environmental controversies.”

So what might be done?  Sarewitz suggests that “bringing the value disputes concealed by —and embodied in — science into the foreground of political process is likely to be a crucial factor in turning such controversies into successful democratic action.”  If politics could no longer hide behind scientific controversy the parties would have to engage in the ordinary give-and-take of politics to identify areas of consensus, mutual interests, or low-stakes options.  Science could then be used more appropriately to “support, monitor, and assess the implementation of policies that have been selected through the political process.”

The PMJM debate – a surrogate for the debate over the value and effects of the Endangered Species Act – could be reframed as an examination of how we as a society value preservation of sensitive habitats, species diversity, and property rights, and what compromises we are willing to make.  If we were to do this, we would be discussing the practical methods of preserving sensitive riparian areas and what is fair to landowners - rather than arguing over the meaning of mouse DNA.         

Anne Ruggles