IMPACT OF AGRICULTURAL INTENSIFICATION OF PASTORAL SYSTEMS ON BIRD DISTRIBUTIONS IN BRITAIN 1970-1990

The distribution of six species of birds known to depend on extensive pastoral systems, as published in atlases of breeding birds, was mappe d in Britain for two time periods: 1968-1972 and 1990-1992. The specie s chosen (corncrake Crex crex, golden eagle Aquila chrysaetos hen harr ier Circus cyaneus, stone curlew Burhinus oedicnemus, chough Pyrrhocor ax pyrrhocorax and red-backed shrike Lanius collurio) are known to be declining or vulnerable across large parts of their European range. Su mmed species distribution was compared with available data on the dist ribution of low intensity agricultural land in Britain. In 1990, bird and land-use distribution was similar. Thus it is concluded that it ma y be possible to use summed species distribution to predict areas wher e ecologically beneficial fanning systems exist elsewhere in Europe. M ost coincidence in species distribution now occurs in Scotland, northe rn England and Wales. However, large parts of mid-west Scotland have l ess selected pastoral species than in 1968-1972, The most obvious chan ges have occurred throughout East Anglia, the south-east and south-wes t of England. There has been significant fragmentation of coincidence along the north Norfolk coast and along the ceases of Suffolk and Esse x. The extent of summed distribution of the indicator bird species cho sen declined and fragmented dramatically between 1970 and 1990. There was a significant negative relationship between livestock units per he ctare (both sheep and total), and mean species coincidence (average nu mber of species occurring in each 10km(2)) for six regions in Scotland and northern England in 1990. In each of these six regions, mean spec ies coincidence declined as sheep livestock units per hectare increase d between 1970 and 1990. The need for changes to agricultural policies at the level of the European Community in order to reverse this serio us conservation problem, is discussed. (C) 1997 Elsevier Science B.V.