Large-scale habitat use of some declining British birds.
Abstract
A study was conducted of the large-scale habitat use of 8 species of breeding birds using data collected across Britain during 1995. The species studied were skylark (Alauda arvensis), dunnock (Prunella modularis), blackbird (Turdus merula), song thrush (Turdus philomelos), starling (Sturnus vulgaris), linnet (Carduelis cannabina), bullfinch (Pyrrhula pyrrhula) and reed bunting (Emberiza schoeniclus) which are all linked by roughly synchronous population declines over the last 25 years in southern Britain. Discussion is limited to the conservation status of these species. Breeding densities were estimated for broad habitat types (deciduous woodlands, coniferous woodlands, mixed woodland, scrub, heathlands, grasslands, urban, suburban, riparian and farmlands) and these were used to estimate population sizes within habitat types. Confidence limits on the estimates were derived using a bootstrap procedure. For most species considered, farmland held a high proportion of their population (in excess of 50% for 4 species), reflecting the predominance of this land use across Britain. It is suggested that sympathetic changes in farming practices are likely to provide the best mechanism for improving the status of these species. Substantial proportions of particular species occured outside farmland, different species in different habitats. A considerable proportion of skylarks occured on upland moor, bullfinches in wooded habitats, and reed buntings in riparian habitats. Conservation of this group of species thus requires appropriate management of the wider countryside. Habitats associated with human habitation hold >20% of the British populations of blackbird, song thrush and starling, and considerable numbers of other species. It is concluded that the management of parks, gardens and other green spaces may have an important impact on bird populations and should not be neglected by conservationists.