Testimony of David S. Wilcove, Senior
Ecologist, Environmental Defense,
Before the Fisheries, Wildlife and Water
Subcommittee
Of the Senate Environment and Public Works
Committee
May 9, 2001
Two simple questions underlie much of the controversy pertaining to the listing of plants and animals as threatened or endangered under the Endangered Species Act. Developers, loggers, miners, business leaders, and other members of the regulated community wonder whether all of the species currently on the endangered species list are truly in danger of disappearing. Because the Endangered Species Act can pose significant economic costs to these people, they are understandably concerned that only species truly at risk of extinction be afforded such protection. Conservationists, on the other hand, worry that many rare plants and animals are not making it onto the endangered species list and are therefore being denied the protection they desperately need. Neglect becomes a prelude to extinction.
The
best available scientific information indicates that the answer to the first
question—are lots of undeserving species somehow finding their way onto the
endangered species list? —is a resounding “no.” And new data demonstrate that the answer to the second
question—are lots of gravely imperiled species somehow failing to receive
protection under the Endangered Species Act? —is an equally resounding
“yes.” Below, I review these studies
and their implications for administration of the Endangered Species Act.
In
1993, Margaret McMillan, Keith Winston, and I published a paper in the
peer-reviewed journal Conservation
Biology in which we examined the population sizes of U.S. species proposed
for listing or added to the endangered species list from 1985-1991 (inclusive).[1] Nearly 500 plants and animals were either
proposed for listing or added to the list during that seven-year period. We discovered that the median population
size of a vertebrate animal (mammal, bird, reptile, amphibian, or fish) at time
of listing was 1,075 individuals. The median population size of an invertebrate
animal at time of listing was fewer than 1,000 individuals, while for plants,
it was fewer than 120 individuals. (In
fact, 39 plant species were listed when 10 or fewer individuals were known to
exist.) These low numbers of
individuals were clustered in a small number of populations: For animals, the
median number of populations at time of listing was fewer than 3; for plants,
it was 4. By any scientific standard,
such low numbers make these species highly vulnerable to extinction.[2]
One way to highlight this point is to note that half the animals added to our
endangered species list are rarer even than the giant panda.
More
recently, Dr. Sandy Andelman of the National Center for Ecological Analysis and
Synthesis at the University of California—Santa Barbara has updated our study,
using listing data from 1996-2000. She,
too, found that the population sizes of plants and animals added to the
endangered species list during this period were extremely low, meaning these
species were highly vulnerable to extinction and worthy of federal protection.[3] For vertebrate animals, in fact, the
population sizes of those species added from 1996-2000 were even lower than the
population sizes of species added from 1985-1991.
Thus,
the scientific studies done to date—as opposed to the rhetoric often heard from
opponents of the Endangered Species Act—strongly support the idea that the
species finding their way onto the endangered species list fully fit the
statutory definitions of “endangered” and “threatened” species.
Of
course, it can be argued that the numbers I have cited are only as good as the
data upon which they are based. If the
U.S. Fish and Wildlife Service relies upon incomplete or inaccurate data when
it decides to list a species, then it could end up listing a species that, upon
further investigation, turns out to be fairly common. Supporters of this hypothesis are quick to point out that
previously unknown populations of rare plants and animals are sometimes
discovered after a species has been listed.
The reason is simple: By putting a regulatory spotlight on a particular
rare species, the Endangered Species Act forces developers, federal agencies,
and others to search more diligently for it.
The
fact that additional populations are discovered is not, by itself, evidence of
a problem with the listing process.
Most ecologists would predict that, with more searching, more
populations would be found. A problem
arises only when the number of new populations is so great as to make one
question whether the species ever belonged on the endangered species list. Thus, it is worth noting that of the more
than 1,200 plants and animals that have been placed on the endangered species
list since 1973, only 5 have been removed from the list because they turned out
to be far commoner than originally believed.[4] This amounts to less than one-half of one
percent of the total list.
Approximately 7 additional species have been removed from the list
because additional studies revealed that they were not valid taxonomic entities
(i.e., they turned out not to be distinct species, subspecies, or populations
as required by the law).
In
summary, the available evidence clearly indicates that virtually all of the
U.S. plants and animals added to the endangered species list represent valid
taxonomic entities at genuine risk of extinction.
To
answer the second key question—Are there significant numbers of imperiled
species in the U.S. that have not been added to the federal endangered species
list? —we are fortunate to have
available a new book produced by The Nature Conservancy (TNC) and the
Association for Biodiversity Information (ABI).[5] Precious
Heritage: The Status of Biodiversity in the United States is a compilation
and analysis of data gathered by the natural heritage programs now established
in all 50 states, plus TNC and ABI. It
provides what is unquestionably the most up-to-date and complete picture of the
status of American wildlife.
TNC
and ABI rank plant and animal species on a scale from 1-5. Species classified as G1 (the “G” indicating
that the rank in question pertains to the entire or “global” range of the
species) are considered “critically imperiled.” Such species typically occur in 5 or fewer places or have a total
population of 1,000 or fewer individuals.
A G2 species occurs in 6 to 20 places or has 1,000 to 3,000 individuals
left. It is considered “imperiled.” A G3 species is classified as
“vulnerable.” It typically occurs in 21
to 100 places or has 3,000 to 10,000 individuals remaining. Species ranked G4 or G5 are in no immediate
danger.[6] Note that all of these ranks are based on
numbers of individuals and populations; they do not take into consideration the
degree or immediacy of the threats facing these species.
The
authors of Precious Heritage have
identified no fewer than 1,385 U.S. plants and animals with a rank of G1
(critically imperiled). An additional
1,737 species are classified as G2 (imperiled), while 3,338 are classified as
G3 (vulnerable).[7] By any reasonable measure, all of the
species ranked G1 or G2 would qualify for listing as endangered or threatened
under the Endangered Species Act; these two categories alone contain well over
3,000 species—more than double the current endangered species list. And in all likelihood, a significant
fraction of the species classified as G3 (vulnerable) would pass muster for
listing, too. Thus, there are a great
many rare plants and animals that are at risk of extinction but are not yet
protected under the Endangered Species Act.
Given
what we now know about the endangered species list, what steps can be taken to
reduce the risk of erroneous listings and to increase the proportion of
deserving species covered by the Endangered Species Act? Although the risk of an erroneous listing is
small, Congress can reduce it even further by providing additional funds for
biological inventories and taxonomic research.
To
reduce the backlog of deserving species awaiting protection, Congress must
greatly increase funds to the U.S. Fish and Wildlife Service and National
Marine Fisheries Service for listing activities. From 1991-2000, the U.S. Fish and Wildlife Service added an
average of 63 U.S. species per year to the list. At that rate, assuming a backlog of about 2,000 imperiled,
unlisted species, it would take the Service nearly 32 years to catch up. By that time, many of these rare plants and
animals may be gone. A reasonable goal
would be to erase this backlog within a decade. Doing so would require a tripling of the annual appropriation to
the Service for listing and related activities, to approximately $20 million in
FY2002.
Finally,
we must not forget that simply placing a rare plant or animal on the endangered
species list does not guarantee its survival, much less its recovery. If, as the data indicate, most species are
added to the list only when their populations have reached critically low
levels, then we must find ways to increase those populations. Doing so usually entails restoring or
enhancing their habitats. For species
that depend upon private lands, the key to restoring their habitats is to
enlist the cooperation of the landowners.
Incentive-based approaches, such as the U.S. Fish and Wildlife Service’s
safe harbor program or its Endangered Species Landowner Incentive Program, have
proved to be very successful in making landowners active participants in
recovery efforts. More support for
programs such as these will go a long way toward saving our imperiled wildlife
while removing much of the controversy associated with the Endangered Species
Act.
[1] Wilcove, D.S., M. McMillan, and K.C. Winston. 1993. What exactly is an endangered species? An analysis of the U.S. endangered species list: 1985-1991. Conservation Biology 7: 87-93.
[2] IUCN/World Conservation Union. 1994. IUCN red list categories. Prepared by the IUCN Species Survival Commission, 30 November.
[3] S. Andelman, pers. comm., May 4, 2001.
[4] These are Tumamoc globeberry, Rydberg milk-vetch, McKittrick pennyroyal, pine barrens tree frog (Florida population), and Dismal Swamp southeastern shrew. See: D. Wilcove and M. McMillan. 1994. An analysis of erroneous listing proposals and decisions under the Endangered Species Act. Environmental Defense, Washington, DC; http://ecos.fws.gov/webpage/webpage_delisted.html. These numbers are current as of May 4, 2001.
[5] Stein, B.A., L.S. Kutner, and J.S. Adams. 2000. Precious heritage: The status of biodiversity in the United States. Oxford University Press, Oxford, UK.
[6] Stein et al. (2000), Table 4.2, p. 97.
[7] Stein et al. (2000), Table 4.4, p. 104.