In the good old days of the 1970s, species were chosen for the endangered species list primarily because they had been overexploited or because chemical pollutants threatened their survival and reproduction. Biologists deemed a few dozen species, including the bald eagle, American alligator, and whooping crane, to be threatened with extinction.

Since that first endangered species list appeared, there have been a few success stories. Some species have achieved removal from the dreaded list and earned the phrase "recovered" next to their name. Population trajectories of the peregrine falcon and the blown pelican began to switch direction when DDT, which caused egg-shell thinning and therefore resulted in few offspring, was banned from use in the United States (although we cannot forget that it is still produced here and used abroad).

Other species weren't so lucky. Fast-forward to the year 2001, when over 80 percent of the nearly 1000 species on the list are there because humans have severely degraded or destroyed their habitats. While the bald eagle and the peregrine falcon lead the ranks of the recovered, species like the black-footed ferret remain precariously close to extinction. Black-footed ferrets cannot recover until we address the reasons for their decline — habitat loss and degradation. Black-footed ferrets are famous for their hearty appetite for prairie dogs, and prairie dog towns throughout the American West continue to disappear.

Put simply, most endangered species are in trouble because of habitat loss, and until that problem gets addressed, their endangerment will persist. The terms of the ESA, meanwhile, stop short of the solution to this problem.

While the rules of the ESA prohibit killing, collecting, capturing, or generally harassing species that are endangered, they make one important exception. Section 10(a) states that private citizens can receive permission for "incidental take" (another way of saying "killing, collecting, capturing, or generally harassing") of an endangered species as long as they develop a plan to compensate for the damage. Compensation means "mitigation," promoting the survival of that species in some other way.

This is an important provision, because much of the habitat for most endangered species is in private ownership. Private landowners engaged in habitat destruction hire environmental specialists to develop mitigation plans. These plans typically propose to compensate for habitat or species destruction by either re-creating habitat, as is commonly done in wetland mitigation, or by moving animals to a new location, such as the ever-so-close-to-home example of the black-tailed prairie dog.

In theory, mitigation provides a happy ending, a way for people with conflicting interests to get what they want. And yet, as a biologist whose research focuses on plant and animal responses to loss and fragmentation of their habitats, I clearly realize that mitigation is a myth.

The American Heritage Dictionary formally defines a myth as "an unproved collective belief that is accepted uncritically and is used to justify a social institution." To illustrate the concept, my dictionary uses as an example the age-old belief of the biological inferiority of slaves, which has been used for centuries to support slave societies.

So what's mythical about mitigation for endangered species? Isn't mitigation a good thing, deserving of any justification it can get? Wouldn't all those species disappear if we didn't create an alternative habitat or move them out of harm's way?

Yes, all other things being equal, mitigation for habitat destruction is undoubtedly better for endangered species than no mitigation at all. However, mitigation carries one big risk: It lulls our society into a sense of complacency. We are soothed and reassured by the collective belief that when one set of people destroy habitat, another set will come to the rescue by correcting the negative consequences through habitat mitigation.

My research in the Central Valley of California has focused on a rare beetle species that lives only in elderberry bushes growing along streams and rivers. Because of extensive agricultural activity and levee building for flood control, these riparian woodlands have declined to less than 10 percent of their original extent. The beetle was legally protected by the ESA in 1980, so any human activities that degrade or destroy elderberry bushes require mitigation.

Mitigation sites for this beetle have literally sprouted throughout the Central Valley over the past 20 years. But do these artificial habitats look, smell, taste, and nourish like the real thing as far as the beetles are concerned? I investigated these mitigation sites and compared them to naturally occurring sites that support beetle populations.

While one of the mitigation sites did support a healthy beetle population, none of the others that I examined did. The bushes were too small, too unhealthy, or too far from natural populations to encourage beetles to colonize the new sites. The successful site was a large area with mature trees close to an extensive, native riparian woodland.

Creating new habitats for rare species, I learned from this study, takes a lot of effort. The people responsible for the initial habitat destruction are legally required to continue habitat mitigation efforts until they are proved successful. Unfortunately, this promise is rarely fulfilled, as more and more cases weigh down officials responsible for the legal enforcement of habitat mitigation.

Another example comes from closer to home: relocation of black-tailed prairie dogs. Humans decide that we'd like to live, or shop, or play where the prairie dogs are, so we decide to move them someplace else. Witness the number of prairie dog colonies that have been relocated away from the Boulder Turnpike.

Do those refugees make it? The latest research suggests a high mortality rate during relocation, which is not surprising given that prairie dogs are social animals and live in family groups. During relocation, family members are often separated from one another. In undisturbed colonies, family members call to each other when danger approaches. When family groups are disrupted, individual survival declines.

These two examples of habitat mitigation are just the tip of the iceberg. Hundreds of habitat mitigation plans are in operation nation-wide, yet we know very little about the biological efficacy of such efforts.

In suggesting that habitat mitigation falls neatly into the realm of an unproved collective belief, I encourage you to question the assumptions and practices we take for granted. As a species, human beings have a valuable capacity to re-examine and rethink their habits of mind. The myth of mitigation is a leading candidate for reappraisal. Call that myth into question, and all the good reasons to avoid and protect native habitats and species, in the first place, become unmistakable and compelling.

Humans are destroying and creating habitat at an alarming rate, with federally motivated humans moving plants and animals from here to there. Step back and look at this process from a distance, and it seems quite ridiculous.

Wouldn't it be easier just to save the time, money, and effort of creating new habitats by steering clear of rare habitats in the first place? Wouldn't conservation be the most conservative — and the wisest — strategy?

Sharon Collinge is an assistant professor of biology and environmental studies and serves on the Faculty Advisory Council of the Center for the American West at the University of Colorado-Boulder.

Copyright 2001 The Daily Camera

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