Regional IUCN red listing: the process as applied to birds in the United Kingdom

The World Conservation Union (IUCN) has developed guidelines that enable the assessment of extinction risk at a regional scale. We used these guidelines to assess the,extinction risk of birds in the United Kingdom for comparison with an existing assessment of conservation status. Sixty-four species were categorized as regionally threatened, of which 12 were critically endangered. The categorizations of the 223 species assessed agreed broadly with those from the existing UK system, which considers more than extinction risk, thus giving a more complete assessment of conservation status. There was, however, a tendency for the IUCN process to give higher risk status to edge-of-range species (some of which are relatively recent colonists considered of. comparatively low conservation concern) and low status to those that have declined substantially but remain common (such as many farmland birds, the focus of considerable conservation, effort in the United Kingdom). The final red list depended heavily on the subjective decisions made during the assessment process. An alternative interpretation of the guidelines could have resulted in as many as 19 or as few as 6 species being listed as critically endangered. We recommend the revision of the IUCN guidelines to reduce this subjectivity, in particular with respect to the effect of extralimital populations on the likelihood of regional extinction, and hence the potential for variation in the manner of application between regional red-list assessors. Preventing extinction does not have to be the principal driving force behind conservation action at a regional scale if the continuance of a species is safeguarded in other regions.