Consistency and Transparency of Endangered Species Listings

Testimony by Lev Ginzburg

State University of New York At Stony Brook, Stony Brook, New York, and

Applied Biomathematics, Setauket, New York

Determination of endangerment status is one of the most critical steps for reaching the objectives of the Endangered Species Act; it is crucial for implementing effective conservation strategies and for apportioning limited financial and human resources for species conservation. Yet, the protocol used by the US Fish and Wildlife Service for listing species under the Endangered Species Act has been criticized as being arbitrary, because the system lacks explicit guidelines by which these decisions are made.

A risk classification system utilizing explicit guidelines and quantitative data would promote consistency in listing decisions and expedite the listing process. One such system has received wide acceptance from the international community and has been hailed by the National Research Council as the “most important scientific effort to date to reach consensus on standard criteria for assigning taxa to threat categories in a uniform, objective manner.” This system was developed by the World Conservation Union (IUCN, formerly known as the International Union for the Conservation of Nature). IUCN is the principal international organization involved with categorizing species by extinction risk. Since the 1960’s, it has been producing Red Data Books and Red Lists, which are among the most important tools for monitoring biodiversity at a global level.

Under the system used by the U. S. Fish and Wildlife Service, a species qualifies for listing if its populations meet one of five qualitative criteria, such as present or expected future loss of habitat, overharvesting, disease or predation. Species that qualify for listing are then ranked based on magnitude of threat, immediacy of threat, and taxonomic distinctiveness. There are no threshold values for deciding the magnitude or immediacy of threat. The final decision to list a species as either endangered or threatened is based on the level of perceived extinction risk. An endangered species is defined as being “in danger of extinction throughout all or in a significant part of its range” and a threatened species is “likely to become endangered throughout all or a significant part of its range”.

The IUCN listing process is carried out by its specialist groups, each concerned with a particular taxonomic group. Species satisfying one of five criteria, based on thresholds of ecological variables such as population size, population growth trend, geographic distribution, and extinction probability, are classified into one of IUCN’s three threatened categories of Critically endangered, Endangered, and Vulnerable. Species not meeting these criteria are given the status Least Concern. Threshold ranges of quantitative variables within each of five criteria separate each category of endangerment. In all, 12 quantitative variables are examined for each species under this system. If not all relevant data are available, as is often the case; a species may still be evaluated under this system because of the many variables examined.

The IUCN listing process was developed under wide consultation and is now recognized internationally by the public and scientific community. The lists of threatened species developed by IUCN are among the most widely used by conservationists around the world. The IUCN criteria were designed to detect risk factors for organisms of widely different taxonomic groups. While not all criteria may be relevant for a particular taxon, there are criteria relevant for assessing extinction threat of all groups (except microorganisms).

One difference between the IUCN and FWS systems is the efficiency and speed of the listing process. The most recent IUCN Red List includes over 18,000 species that have been assessed in the 5 years since the new IUCN system took effect. By contrast, the number of species listed by the FWS in the last 20 years is about one-tenth of this number.

Resources for conservation of species are limited. It is, therefore, imperative that decisions are made carefully to focus on species that will benefit most from conservation actions. In addition, many species at risk of extinction cannot afford an inefficient listing protocol. These considerations are mentioned in the endangered Species Act of 1973, yet the present process is both slow and subjective.

The most important difference between the IUCN and FWS systems is their transparency. The FWS relies heavily on qualitative criteria and expert judgment, and therefore often seen as ambiguous and subjective. The IUCN system is based on objective criteria, and results in efficient and scientifically defensible decisions. It makes use of explicit guidelines for evaluating different variables that contribute to extinction risk and uses quantitative thresholds to determine degree of endangerment. As a result, decisions are consistent between people and specific reasons for each listing decision are clearly defined.

For most species, data that are valuable for evaluating extinction risk are deficient in one or more areas. It may not be possible to gather all relevant data for some species. Data collection may be costly or delaying action to gather all relevant data may place that species in greater danger of extinction. The IUCN system uses multiple criteria to accommodate this problem. Because meeting any one criterion is sufficient for listing, it is possible to list a species in a high threat category if sufficient data is only available for one criterion.

There is always some uncertainty involved in estimating extinction risk in the form of measurement error, probabilistic predictions, or semantic ambiguity. When this uncertainty is simplified for analysis, it is difficult to prevent human biases from entering the decision making process. New methods have been developed that allow the evaluation of species according to the criteria of IUCN while objectively dealing with uncertainty in data. This allows efficient and non-biased classification of species of concern. However, such methods of dealing with uncertainty are applicable only to protocols that are based on objective, quantitative criteria, rather than subjective opinions.

To improve the federal system under which threatened and endangered species are listed, it is essential that more explicit criteria and clear thresholds be incorporated, as in the IUCN system. There is a large amount of similarity in the nature of the factors considered under the USFWS and IUCN listing systems. A system similar to that of IUCN can easily be implemented in the U.S., without requiring a change in the Endangered Species Act itself. Such a change will make the Act more efficient, objective, and science-based in dealing with the listing and de-listing of threatened and endangered species.