THE POPULATION STATUS OF BIRDS IN THE UK.

THE CRITERIA:-

Seven quantitative criteria were used to assess the population status of each species and place it onto the red, amber or green list. These criteria are listed below. The review excluded species that are not native to the UK and those that occur irregularly as vagrants or scarce migrants.

• GLOBAL CONSERVATION STATUS
  Species assessed as Globally Threatened were placed on the red list.
• RECENT DECLINE
  Species whose breeding or non-breeding population declined, or range contracted, rapidly (by more than 50%) or moderately (by between 25 and 49%) over the last 25 years were placed on the red and amber lists respectively.
• HISTORICAL DECLINE
  Species whose populations declined severely between 1800 and 1995 were placed on the red list, except for those that have recovered substantially (more than doubled) in the last 25 years, which were amber-listed. In earlier assessments, all species showing a serious historical decline were red-listed, but in this assessment the success of recent conservation action has been recognised by moving recovering species to the amber list.
• EUROPEAN CONSERVATION STATUS
  Species whose population status is unfavourable in Europe (but which are not Globally Threatened) were placed on the amber list.
• RARE BREEDERS
  Species with a mean population size of 1-300 pairs breeding annually over the last five years were placed on the amber list. If a full census was carried out in a single year, the result of this was used instead of a five-year mean.
• LOCALISED SPECIES
  Species for which 50% or more of the breeding or non-breeding population occurs at 10 or few sites were placed on the amber list. This criterion was used because a species whose population is confined to a few sites faces a greater threat from chance events than one whose population is widespread. The sites considered were either Important Bird Areas (identified by BirdLife International) or Special Protection Areas (designated under the European Union’s Directive on the Conservation of Wild Birds).
• INTERNATIONAL IMPORTANCE
  Species with 20% or more of their European population breeding in the UK were placed on the amber list, as were non-breeding wildfowl with 20% or more of their northwest European population occurring in the UK and non-breeding waders with 20% or more of their East Atlantic Flyway population occurring in the UK. This criterion is different from the others as it is a measure of the UK’s responsibility for each species rather than the extent to which species are threatened.

Red list species are those that are Globally Threatened according to IUCN criteria; those whose population or range has declined rapidly in recent years; and those that have declined historically and not shown a substantial recent recovery. Amber list species are those with an unfavourable conservation status in Europe, those whose population or range has declined moderately in recent years; those whose population has declined historically but made a substantial recent recovery; rare breeders; and those with internationally important or localised populations. Species that fulfil none of the criteria are green-listed.

FARMLAND BIRDS

The 1996 assessments helped to focus attention on a suite of widespread but rapidly declining birds of farmed land, such as the turtle dove, the skylark and the corn bunting. It is generally accepted that these species have declined because of agricultural intensification, and in the last few years a range of schemes have been introduced to help them. All of the birds of farmed land that were on the red list in the earlier assessments are still there. In addition, another farmland bird, the yellowhammer, has joined them. Many red list species remain relatively common in the countryside despite substantial declines.

WOODLAND AND URBAN BIRDS

Birds from two new groups appear on the red list: lowland woodland birds and urban birds. The red-listed woodland birds are the lesser spotted woodpecker, the marsh tit and the willow tit, which have declined by 73%, 50% and 80% respectively over the last 25 years. A number of other woodland species have entered the amber list. The urban species new to the red list are, remarkably, the house sparrow and the starling, both of which were formerly ubiquitous but have declined by more than 60%. In contrast to the situation with farmland birds, we do not know why these woodland and urban species have declined, and urgently need to find out. As with farmland birds, some of these species remain quite common despite severe declines.

NORTHERN/UPLAND BIRDS

 Several species characteristic of Scotland, Wales or northern England, such as the capercaillie and the black grouse, remain on the red list because of continuing steep declines. Others, such as the corncrake and the white-tailed eagle, are still red-listed although their numbers are increasing due to successful conservation action. One upland bird, the ring ouzel, is new to the red list.

SUCCESSES

Although the overall number of species on the red list has increased since the last assessment (from 36 to 40), five species have moved from red to amber. The populations of the red kite, marsh harrier, osprey, merlin and Dartford warbler have more than doubled in the last 25 years, even though they had declined substantially previously. Much of the recent increase in these species is due to the success of targeted conservation action.