NCPA | Study #303, Bad for Species, Bad for People: What’s Wrong with the Endangered Species Act and How to Fix It

When confronted with the embarrassing reality that the ESA is harmful to species, the Act’s proponents fall back on two arguments they claim prove otherwise.

First, they contend that although some species that were listed are now extinct, far more would have perished without the ESA. One study claimed that but for the Act, 192 listed species now would be extinct, rather than the seven that had been delisted due to extinction at the time of the study’s publication.²⁵ However, this assertion is fundamentally flawed. It applies a very rough (and likely inappropriate) estimate of extinction rates for all species to those listed under the ESA. Despite this, ESA advocates have cited the study as evidence the Act works.²⁶ Official Reasons for Delisting 46 Species

Official Reasons for Delisting 46 Species

The more widespread variant of the extinction prevention argument is that almost all species listed under the ESA are not extinct. “[T]he law is a profound success,” claims the National Audubon Society. “According to the U.S. Fish and Wildlife Service, the ESA has prevented extinction for 99 percent of the species that are listed as endangered or threatened.” ²⁷ This claim is unsupportable. Due to the fact that imperiled species are by definition the most susceptible to extinction, statistically, some would have perished with or without the ESA’s intervention. There is no valid data to support the claim that the ESA has stemmed the tide of extinction for listed species, much less that the Act is responsible for the continued existence of 99 percent of the listed species.²⁸

Second, ESA proponents claim that the Act is responsible for the Service’s characterization of the majority of listed species as “stable” or “improving.” The National Wildlife Federation claims that of the listed species whose status is known, 68 percent are stable or improving. The Federation also says, “The longer a species enjoys the Endangered Species Act’s protections, the more likely it is that its condition will stabilize or improve.” ²⁹

However, these claims cannot be substantiated because they are based on invalid data. Every two years the Service sends out a questionnaire to the field biologists responsible for various species, asking them to categorize their species as improving, declining, stable or unknown.³⁰ But the results are flawed in two basic ways. First, the data are not collected using any sort of standardized methodology that is replicable or that yields meaningful results. Second, data are not collected every year for all species. Others have also noticed that these data are not valid, such as: David Wilcove, formerly with Environmental Defense and currently a professor at Princeton University; the National Research Council’s report on the ESA; and Charles Mann and Mark Plummer, authors of a book and several articles on the Act.³¹ [See the sidebar on flawed data.]

Flawed Data on Species’ Status

Every two years, the U.S. Fish and Wildlife Service the Service reports to Congress on the status of species listed under the Endangered Species Act. The reports are based on questionnaires sent to field biologists responsible for studying particular species. However, these categories yield data that are essentially meaningless for six principal reasons.

First, there is the issue of snapshots vs. trend data. Does a given field biologist interpret the status of a particular species at the time the questionnaire is completed (a snapshot) or, perhaps, the species’
population trend over time? Clearly, a trend over time yields a superior result, but the questionnaire
does not require this method.

Second, there is no standard for determining at what level of health a species is categorized as stable. The species could be stable though hovering perilously close to extinction, relatively healthy with a large and robust population, or somewhere in between.

Third, there is no standard for assessing the rate at which species’ population levels are improving
or declining. For the data to be accurate, it needs to be quantifiable, but it is not. The data gathered by the questionnaire is qualitative.

Fourth, if the population of a species increased markedly, but then declined slightly just prior to the completion of the questionnaire, it is not clear whether the field biologist recorded the species as increasing or decreasing. The converse also applies. Since the Service has not kept annual data on the status of all species, its data cannot be used to assess the status of all species.

Fifth, the postings of Service field biologists change frequently, so the person filling out the questionnaire for a given species may be different for each survey. Different biologists may interpret the questionnaire differently, and one biologist’s knowledge of a given species might be far better or worse than a predecessor’s. The answers reflect one person’s evaluation of a species at one point in time, and therefore the status of a species may change between surveys simply because different people complete them.

Sixth, the Service skews the data by mistakenly assuming every species is declining at the time it is listed, and when some species are later categorized as stable or improving, it automatically credits the change to the ESA, overstating its effectiveness. For example, in 1978 the Service listed the Rydberg
milk-vetch, a plant found in Utah, and assumed that it was declining.¹ But, according to the U.S. Forest Service, the agency on whose land most of the milk-vetch’s population grows, “prior to 1978 ... the Forest Service had not completed inventory work or gathered any baseline data on the species.” ² Without baseline data, the service could not be certain that the milk-vetch’s population was growing, shrinking or imperiled. The Forest Service later found the plant was plentiful, with more than 300,000 plants in 13 currently known populations. The Service delisted the plant in 1989 due to “recovery,” meaning the Act got the credit. Only in 2005 did the Service correct this “mistake” and recategorize the milk-vetch as “data error,” meaning the plant should not have been listed in the first place.³

¹ Federal Register, Vol. 43, April 26, 1978, pages 17,910-16.

² Draft memorandum from J.S. Tixier, Regional Forester, U.S. Forest Service, Intermountain Region, Ogden, Utah, to forest supervisors of the Dixie and Fishlake National Forests.

³ Federal Register, Vol. 54, September 14, 1989, page 37,941.