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Question 7.

For some taxa it may be necessary to apply a more detailed analysis of absence after the species' reported EED in order to accurately account for its status. In our survey of freshwater fish, for example, it was determined that because they are so elusive, extant species could easily be overlooked and wrongly considered extinct unless these additional criteria were applied:

a) significant but unsuccessful attempts had been made to relocate the species after its noted absence (either in a search targeted toward that species or in a sampling exercise that covered the expected range of that species),

b) there had been a decline of that particular species, or an environmental threat to it, before the EED.

To what degree would it be necessary to apply these additional criteria to your group in order to be more certain that an extinction took place?

  • Comments by CREO Chairman, Ian Harrison, have been added to some of the responses below -- in underlined text.

    Amphibians Advisory Panel

    Comment 1: subcriteria (a) and (b) are applicable to amphibians.

    Comment 2: subcriteria (a) is more important than (b). For the most studied species it seems that population decline is universal at 1-4 % per year

    Comment 3 : subcriteria (a) is sufficient.

    Comment 4: reliability of survey technique is important. Some surveys have been perfunctory and are therefore unreliable. Some purported reliable surveys produce bizarre results purely because the surveyors neglected basic biological information - for example, a winter survey would suggest that the most North American migratory bird species are extinct. (This indicates the importance of surveys by reliable fieldworkers and the importance of thorough surveys at representative times of day/month/year.)/BLOCKQUOTE>

    Birds Advisory Panel

    Comment 1: subcriteria (a) and (b) can be separate and both may apply — it may be better to combine them as a "may survive" category.

    Comment 2: these subcriteria are vital for all groups. However, fieldnotes can indicate the species is not found even though it is still extant (this is a problem associated with making sampling as complete as possible, although, of course, it is often impossible to be really sure that sampling is complete).

    Comment 3: it must be emphasized that intensive, targetted searching must have brought null results. There are several New Zealand species for which no, or only private, random searches have been made. The criterion of the continued presence of the adverse factors (predators, habitat degradation) have been used as proxy evidence that survival is not possible.

    Comment 4: additional criteria are probably not necessary, except to modify the application of the 50 year rule where this period may be too short to indicate the extinction of some cryptic and/or potentially widespread species. It is, however, critical always to consider issues of crypsis, intensity of search, and difficulty of identification (photos) in judgements. (Some of these issues are covered by the suggested sub-criteria; perhaps there should be some indication of relative crypsis or ease of identification, if this can be done practically).

    Coleoptera Advisory Panel

    Comment 1: the two criteria nicely parallel the Heritage network approach and at least one state Endangered Species Act (Mass.) Whether or not they need to be applied to a particular group of lepidopterans is case-dependent.

    Comment 2: subcriteria 3a and 3b seem fine, but comparing the extant knowledge of beetle distributions, life cycles and activity periods in many cases will not necessarily improve decisions about listing as extinct or not.

    Comment 3: the criteria may need to evolve for themselves for a while, for beetles.

    Fishes Advisory Panel

    Comment 1: For subcriterion (a), it should be added that sampling should have been conducted by a by a competent, experienced and reliable person or team. There have been search parties for many fishes constituted only by aquarists who never got what they looked for. Or national teams who have no idea what they should be looking for.

    The real value of subcriterion (b) is not clear: taking the case of desert fishes, a species could be extinct even without evidence of decline before the EED. It takes just a few hours to install a pump or dump half a ton of concrete to block a spring, or a few seconds to have a pesticide spill and effectively kill all individuals of a species.

    Comment 2: the subcriteria are highly applicable and necessary. When the Tellico Dam on the Tennessee River was Congress approved in the 1970s everyone assumed the snail darter (Percina tanasi) would go extinct. A diligent sampling effort eventually revealed the species in nearby, unaffected habitats.

    Lepidoptera Advisory Panel

    Comment 1: evidence of representative sampling through the known and expected range is essential.

    Comment 2: Significant attempts to locate rare butterflies may not succeed, despite the beasts being extant. One of our recent projects on a rare lycaenid butterfly, for example, did not even detect the thing every year, despite the minute population apparently being secure! For such taxa, which I suspect are numerous, even 'presence/absence' data is difficult to get, and there is no practical prospect of acquiring decent life table information for PVA studies or similar.

    Mammals Advisory Panel

    Comment 1: the subcriteria should be applied, mainly for small mammals, pelagic rare cetaceans, or species from "unknown regions."

    Comment 2: subcriteria need to be adaptable to organisms being studied; see question 9.

    Comment 3: these subcriteria are generally OK.

    Comment 4: these probably only have to be applied in rare cases; probably unnecessary for large mammals.

    Molluscs Advisory Panel

    Comment 1: Both criteria could be applied in some circumstances - especially the former. Given the small number of mollusk workers, the data required for (b) is not likely to exist except in a small number of cases. (Other panels (e.g. amphibia) have also stated subcriteria (a) is more important than (b) ). In most cases, more than one attempt to find the taxon should be necessary before it is listed as probably extinct. Some other category - possibly extinct or something similar - could be used to flag taxa that need to be assessed in more detail. (The "possibly extinct" category is noted by many people responding to Feasibility Surveys)

    Reptiles Advisory Panel

    Comment 1: subcriteria are absolutely necessary in many instances.

    Comment 2: subcriterion (a) is important, as indicated by the rediscovery of many species especially in the species-rich tropical areas after over a century. (b) is equally relevant in areas that are undergoing rapid ecological change (such as the tropics), where beta (between site) diversity is an important component of the overall high diversity.

    Comment 3: very important to apply these subcriteria.

    Comment 4: Results from field work directed at collecting or locating a given species are relatively easy to interpret. Documenting declines, however, is a much more complicated task especially when there is strong interest in drawing correlates to declines. Recent work on Amphibians in North America, Australia, and Central America clearly demonstrate this. The most difficult part of directed field work is if the range of the species was once very large and was subsequently fragmented. This sort of situation means that there may be many refugia that were not sampled. For reptiles on islands this is much less of a problem because there is really a finite space.