Gray wolves, like this pair on Isle Royale, are listed as endangered in the United States/Michigan Tech
What Is An Endangered Species?
By John Vucetich, Michigan Technological University
Lions and leopards are endangered species. Robins and raccoons clearly are not. The distinction seems simple until one ponders a question such as: How many lions would there have to be and how many of their former haunts would they have to inhabit before we'd agree they are no longer endangered?
To put a fine point on it, what is an endangered species? The quick answer: An endangered species is at risk of extinction. Fine, except questions about risk always come in shades and degrees, more risk and less risk.
Extinction risk increases as a species is driven to extinction from portions of its natural range. Most mammal species have been driven to extinction from half or more of their historic range because of human activities.
The query "What is an endangered species?" is quickly transformed into a far tougher question: How much loss should a species endure before we agree that the species deserves special protections and concerted effort for its betterment? My colleagues and I put a very similar question to nearly 1,000 (representatively sampled) Americans after giving them the information in the previous paragraph. The results, "What is an endangered species?: judgments about acceptable risk," are published in Environmental Research Letters.
Three-quarters of those surveyed said a species deserves special protections if it had been driven to extinction from any more than 30 percent of its historic range. Not everyone was in perfect agreement. Some were more accepting of losses. The survey results indicate that people more accepting of loss were less knowledgeable about the environment and self-identify as advocates for the rights of gun and land owners. Still, three-quarters of people from the group of people who were more accepting of loss thought special protections were warranted if a species had been lost from more than 41 percent of their former range.
These attitudes of the American public are aligned with the language of the U.S. Endangered Species Act -- the law for preventing species endangerment in the U.S. That law defines an endangered species as one that is "in danger of extinction throughout all or a significant portion of its range."
But There Might Be A Problem
Government decision-makers have tended to agree with the scientists they consult in judging what counts as acceptable risk and loss. These scientists express the trigger point for endangerment in very different terms. They tend to say a species is endangered if its risk of total and complete extinction exceeds 5 percent over 100 years.
Before human activities began elevating extinction risk, a typical vertebrate species would have experienced an extinction risk of 1 percent over a 10,000-year period. The extinction risk that decision-makers and their consultant experts have tended to consider acceptable (5 percent over 100 years) corresponds to an extinction risk many times greater that the extinction risk we currently impose on biodiversity! Experts and decision-makers -- using a law designed to mitigate the biodiversity crisis -- tend to allow for stunningly high levels of risk. But the law and the general public seem accepting of only lower risk that would greatly mitigate the biodiversity crisis. What's going on?
One possibility is that experts and decision-makers are more accepting of the risks and losses because they believe greater protection would be impossibly expensive. If so, the American public may be getting it right, not the experts and decision-makers. Why? Because the law allows for two separate judgments. The first judgment is, is the species endangered and therefore deserving of protection? The second judgment is, can the American people afford that protection? Keeping those judgements separate is vital because making a case that more funding and effort is required to solve the biodiversity crisis is not helped by experts and decision-makers when they grossly understate the problem -- as they do when they judge endangerment to entail such extraordinarily high levels of risk and loss.
Facts and Values
Another possible explanation for the judgments of experts and decision-makers was uncovered in an earlier paper led by Jeremy Bruskotter of Ohio State University (also a collaborator on this paper). They showed that experts tended to offer judgments about grizzly bear endangerment -- based not so much their own independent expert judgement -- but on basis of what they think (rightly or wrongly) their peers' judgement would be.
Regardless of the explanation, a good answer to the question, "What is an endangered species?" is an inescapable synthesis of facts and values. Experts on endangered species have a better handle on the facts than the general public. However, there is cause for concern when decision-makers do not reflect the broadly held values of their constituents. An important possible explanation for this discrepancy in values is the influence of special interests on decision-makers and experts charged with caring for biodiversity.
Getting the answer right is of grave importance. If we do not know well enough what an endangered species is, then we cannot know well enough what it means to conserve nature, because conserving nature is largely -- either directly or indirectly -- about giving special care to endangered species until they no longer deserve that label.
Comments
Okay, this is a welcome little article on levels of risk, as well as how "group-think" and "the public would rather afford another case of beer" value judgements tend to drop the level of the conservation discussion to the lowest and most timid common denominator. These factors should not be so relevant to the risk assessments; but, we all know they actually do influence these assessments.
However, the article doesn't really address extinction risk factors themselves with the exception of a passing reference to habitat loss as measured by loss of historic range. Although loss of historic range has become the "go to" standard for communicating extinction risk, it's really a "rear view mirror" sort of lagging indicator of a risk factor's already past effects. It reflects the state of the horses after they've already left the barn and, in that sense, it's a terrible metric for extinction risk 1) because it misses most of the most important risk factors for the most vulnerable species and 2) can be so easily manipulated and so easily used to mislead the public.
As examples of missing the most important risk factors for the most vulnerable species, most of our raptor populations weren't suffering any shortage of habitat or range when DDT came on the scene. While loss of historic range could be misrepresented as a lagging indicator of a problem, it was actually just a lagging indicator of a catastrophic population decline that had almost nothing to do with any loss of historic range. Yes, pollution problems and habitat destruction were issues; but, plenty of habitat was still available, just devoid of raptors due to the unrelated effects of DDT. Wolves are another example, a lefthanded example if you will, of a disconnect between loss of historic range and actual extinction risk factors. The current dramatic resurgence of wolves in the western states is evidence that habitat was and is still readily available and loss of historic range simply documented, if you will, unrelated extirpation forces. In the same way, quoting historic range data says nothing about the most devastating current extinction risk for so many of our most vulnerable species, which is gene pool erosion. It's generally not their habitat or range that is disappearing; they're disappearing from their habitat and discussions of loss of habitat or historic range are often just clouding the issue and missing the point.
Vulnerable native trout, along with many other vulnerable freshwater fish, provide good examples of how historic range discussions can be so easily manipulated and so easily used to mislead the public. The habitat and historic range of a native trout species, for example, are often described on maps and with data on how many "stream miles" the species still occupies. Both of these are misleading because, as native trout are impacted, they move upward in the watershed and into smaller and smaller tributaries that hold smaller and smaller volumes of the species' liquid habitat. When measured in linear stream miles, the data may show only a small drop in the miles occupied by the species when, in truth, the loss of actual usable habitat is far greater than it seems. Similarly, when shown two-dimensionally on a map, the species' historic range may appear to have suffered only a small loss in area when, in truth, the species has lost much of the larger flows in downstream stretches and the loss of actual usable habitat is, again, far greater than it seems. The reverse is true for a salmon species. Historic range discussions may leave the impression that the species still has so much of its downstream and oceanic habitat available when, in truth, the species may depend on only a very few miles of upstream river for spawning and access to those few miles may be blocked by dams.
Historic range assertions can also be used to mislead the public even when they are overestimated. Today, we see efforts to undermine the ESA by shifting focus away from protecting species and toward "habitat improvement" efforts. These are good efforts in most cases; but, in some cases, they seem to focus on disingenuous "bait and switch" types of approaches designed to improve the area's value for grazing or logging as much as for the species at risk. We all need to remember that the range and habitat can be there and be healthy; but, the species can be missing due to other factors.
Again, this is a welcome little article; but, I would like to see as much effort be put into an article or articles assessing the need for a better way to describe species viabilty than just quoting percentages of remaining historic range.