We did not stipulate quantitative
measures for defining when significant attempts had been made to relocate
the species, or for defining when there had been a species decline or
environmental threat (see above), because quantitative measures proved
difficult to develop and apply. Do you think it is necessary to develop
a more quantitative system? If so, do you have any suggestions for how
it could be developed?
Comments by CREO Chairman,
Ian Harrison, have been added to some of the responses below -- in underlined
Amphibians Advisory Panel
Comment 1: no
Comment 2: it is not
necessary at this time to develop quantitative methods. Quantitative
methods for amphibians have been developed and attempted to be applied
at the US national level. This generated controversy. Only need to
find one individual to disprove current extinction.
Comment 3: this is
a very difficult issue to address.
Birds Advisory Panel
Comment 1: no,
quantitative measures are difficult to assign and often spurious.
Comment 2: you have
to have a narrative that makes sense, and it would be good to fit
the key elements into a database. For example, is the glaucous macaw
extinct? We have maybe 10 widely scattered localities in Brazil, Uruguay,
Paraguay and Argentina. How carefully has the range been covered?
Pretty well, but we cannot be sure that it isn't somewhere.
But it is big and blue and you'd think it would have been seen...
But we're dealing with negative evidence - and uncovering the existence
of negative evidence is hard work. We need to piece together habitat
information and a plausible explanation for the taxon's loss before
we determine with defensible authority the current status."
Comment 3: "significant
attempts" should have been made. Perhaps 5 organized attempts, in
appropriate habitat at appropriate season? Other criteria, such as
percent of habitat still available (if known), presence of adverse
factors/influences should be factored in. In New Zealand, species
thought to be critical have been searched for, but for those thought
'extinct', such as laughing owl and South Island kokako, efforts have
been reactionary, relying on reported sightings to initiate effort.
The problem might be resolved by scoring such factors as environmental
damage, presence of predators, years since last report, and having
a cut-off score for acceptance.
Comment 4: there is
no reason for additional quantification at this time. However,
evidence would have to be assessed with the habitat and potential
distribution ranges of the species in mind.
Coleoptera Advisory Panel
Comment 1: in
most cases, available and published collection material will not afford
a very quantitative set of critieria beyond simply inspecting recency
of records. The records themselves are the most compelling sources of
Comment 2: Yes. The
panelist providing this comment has databased all captures for selected
Hawaiian taxa and can quantify past survey days, localities by latitude/longitude
references etc. This allows comparison of effort by decade, century
etc., Quantification of the decrease in representation within comparable
samples can be used to imply factors unfavorable to the species. Prolonged
absence from samples (>50 years, >100 years) lends credence
to an extinction explanation. Think of it as an extinction "out-group"
Comment 3: quantitative
measures would be especially difficult to develop and apply for invertebrates.
Fishes Advisory Panel
Comment 1: no,
fish are the least applicable animals to estimate a species decline
or environmental threat by quantitative measures, because of migration
Comment 2: the concept
of 'quantitative measures' is a good one, but it will unavoidably
remain somewhat subjective. Perhaps a review committee established
under the auspices of the ASIH could provide the necessary degree
of reliability and confidence.
Mammals Advisory Panel
Comment 1: see
Comment 2: quantification
is a problem.
Comment 3: quantification
Molluscs Advisory Panel
Comment 1: Quantitative
measures would be desirable but are probably not practical.
Reptiles Advisory Panel
Comment 1: it
is impractical to define some minimum level of significant attempt.
However, it would be useful to document, as far as possible, what the
nature of such attempts have been in each case; for example, person-hours
of night searches, pit-trap days etc.
Comment 2: a quantitative
procedure is highly desirable in order to make the listing more scientifically
accurate, but an absolutely quantitative system (given the ecological
diversity) may be difficult to develop.
Comment 3: quantitative
measures are not necessary
Comment 4: quantitative
measures for certain taxonomic groups will be important, but the same
measures are not broadly applicable to all groups or all questions.