Sources:
Keith Aubry, (360)
753-7685, kaubry@fs.fed.us
Kevin McKelvey, (406) 542-4163, kmckelvey@fs.fed.us
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Media assistance:
Yasmeen Sands, (206) 732-7823, ysands@fs.fed.us
Dave Tippets, (970) 295-5930, dtippets@fs.fed.us |
PORTLAND, Ore. and FORT COLLINS, Colo. June
23, 2008. Nearly any evidence of the occurrence of a rare or elusive
wildlife species
has the tendency to generate a stir. Case in point: in February
2008, remote cameras unexpectedly captured the images of a wolverine
in the central Sierra Nevada, an area from which the species was
believed to be extinct since 1922. But frustratingly few observations
prove to be so conclusive. So what, then, are managers to make
of unverifiable observations, especially those that are not diagnostic?
Researchers from the U.S. Forest Service’s Pacific Northwest
and Rocky Mountain Research Stations examined three cases of biological
misunderstandings in which unverifiable, anecdotal observations
were accepted as empirical evidence. Ultimately, they found that
this acceptance adversely affected conservation goals for the fisher
in the Pacific states, the wolverine in California, and the ivory-billed
woodpecker in the southeast by vastly overestimating their range
and abundance. The researchers’ findings appear in the current
issue of the journal BioScience.
“
These cases revealed that anecdotal data can be important to conservation
by supplying preliminary data, such as early warnings of population
declines,” said Kevin McKelvey, a research ecologist based
in Missoula, Mont., and the study’s lead investigator, “but
conclusions regarding the presence of rare or elusive species must
be based on verifiable physical evidence.”
In their study,
the researchers found that the dependability of species occurrence
data depends on both the intrinsic reliability
of each record as well as the rarity of the species in question,
because the proportion of false positives increases as a species
becomes rarer. To help managers determine the suitability of evidence
in conservation decisionmaking, the researchers developed a gradient
of evidentiary standards for data that increases in rigor along
with species’ rarity. This “sliding scale” of
standards might permit the use of anecdotal data, the least reliable
form, in decisionmaking when the species in question is common,
for example, but require indisputable physical evidence for a species
thought to be extinct. The authors also encourage professional
societies to debate evidentiary standards for their organisms of
interest and to establish rules for using occurrence data.
“
Over the years, many state and federal management agencies have
placed a lot of emphasis on compiling sighting reports and other
unverifiable wildlife
observations” said Keith Aubry, a research wildlife biologist based in
Olympia, Wash., and one of the study’s co-investigators. “Unfortunately,
the uncritical use of such observations has largely impeded conservation goals,
not advanced them.”
The Pacific Northwest (PNW) and Rocky Mountain Research
Stations are two of seven research facilities of the U.S. Forest Service.
PNW Research Station
is headquartered in Portland, Ore., and has 11 laboratories and centers
located in the Pacific Northwest and about 500 employees. Rocky
Mountain Research
Station is headquartered in Fort Collins, Colo., and has 14 laboratories
and centers
in the Interior West and about 500 employees.
Article citation: McKelvey,
Kevin S.; Aubry, Keith B.; and Schwartz, Michael K. (2008). Using
anecdotal occurrence data for rare or elusive species:
the illusion of reality and a call for evidentiary standards. BioScience.
58(6):
549-555. The article is available online at http://www.bioone.org/perlserv/?request=get-document&doi=10.1641%2FB580611.
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