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Question 10.

In general, can you think of any other criteria or sub-criteria that would be helpful for assessing extinctions in your group?

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

    Amphibians Advisory Panel

    Comment 1: when a species is declared extinct (or, ideally, well before this), an immediate assessment should be made of the available preserved material. It should be ensured that this material is correctly identified. (Surprisingly, this is often not the case; for example, a single, putatively extinct species of frog is represented by a syntypic series of 5 specimens, each of which appears to represent a different species, and each species appears to be extinct. Species in decline deserve this special taxonomic attention to ensure that they are well understood and to prevent an extinction occurring unnoticed.)

    Birds Advisory Panel

    Comment 1: separate out extinctions possibly pre-dating 1500; extinctions in the last 50 years; 'true' resolved extinctions between 1500 and 50 years ago. Then modify these categories according to taxonomic problems, undescribed status, or the possibility of survival; ie., apply modifiers rather than a dichotomous key. See the first comment under Question 11 for further details on this protocol.

    Comment 2: be aware that the proof of extinction is very difficult, especially when the species is at a critically low level - the effort needed to detect the species can be disproportionate to the rewards; e.g. the ivory billed woodpecker may still exist but its possible habitat is an inaccessible swamp in the US. So it is too difficult to look for it - but the supposition that it is there has created moves to delist it from the Endangered Species List. (This indicates that we should be very careful about claiming a species is extinct when we know it can be very difficult to find; the evidence should be expressed in such a way as to show that the extinction requires more testing and the species should be regarded as having some possibility of being extinct or critically endangered until more evidence comes to light).

    Comment 3: covered by comments already made for other questions. The difficulties involved with observations are exemplified by the doubt as to the continued existence of Turdus poliocephalus and Zosterops albogularis on Norfolk Island, which is 5x3 miles and has only a tiny patch of forest remaining.

    Coleoptera Advisory Panel

    Comment 1: for insects we must apply a rarity rule; i.e. it is far easier to document loss of a dominant species than a rare one.

    Lepidoptera Advisory Panel

    Comment 1: Where such information is available, loss/rate of loss of key habitat and resources is the main factor in decline and loss and could be used as a more effective surrogate index of urgency.

    Mammals Advisory Panel

    Comment 1: we need to discuss cases with domesticated mammals. An example we have now some extinct species in the wild but numerous recent domesticated descendants, which are now referred to another species: for example, Bos primigenius - Bos taurus; Equus gmelini - Equus caballus. Some systematists united extinct ancestors and domesticated recent animals in one species. Maybe new subcriteria can be used for such cases. (This seems to be in part a species concept issue; if the domesticated forms are viewed as different species then there is an extinction; if not there is no extinction. However, domestication might be viewed as driving evolution so that, although the species still exists (as a domesticated version) the original form has disappeared. Maybe there is a way of recognizing this by recommending that, if the domesticated form is conspecific with the original wild form, it is recognized as such and classified as "domestic extant" or something similar, but it is not covered any further than that by CREO?).

    Reptiles Advisory Panel

    Comment 1: size (eg. area) of known intact habitat type remaining within the range of the species (and therefore the possibility of the persistence of the particular species.)

    Comment 2: rarity of specimens in museums, for a species or group that reflect cryptic habits. Rarer species in collections may need more than 50 years (Panelists for birds and mammals have made similar statements).