Evaluating the Breeding Bird Survey for producing national population size and density estimates: Capsule The BBS has potential for producing better estimates of habitat-specific densities and population sizes for many UK bird populations than those avail
Publication Type: | Journal Article |
Year of Publication: | 2005 |
Authors: | Newson, SE, Woodburn, RJW, Noble, DG, Baillie, SR, Gregory, RD |
Journal: | Bird Study |
Volume: | 52 |
Issue: | 1 |
Date Published: | 2005 |
ISBN Number: | 0006-3657 |
Keywords: | Acanthis, Acanthis cannabina, Alauda, Alauda arvensis, Alaudidae, Carduelis, Carduelis cannabina, Carduelis chloris, Chloris, Chloris chloris, Coloeus, Coloeus monedula, Columba, Columba palumbus, Columbidae, Communis, Communis communis, Corvidae, Corvus, Corvus monedula, Curruca, Curruca communis, Emberiza, Emberiza calandra, Emberiza godlewskii, Emberizidae, Fringillidae, Linaria, Linaria cannabina, Merula, Miliaria, Miliaria calandra, Palumbus, Passer, Passer domesticus, Passeridae, Prunella, Prunella modularis, Prunellidae, Sturnidae, Sturnus, Sturnus vulgaris, Sylvia, Sylvia communis, Sylviidae, Turdidae, Turdus, Turdus ericetorum, Turdus maximus, Turdus merula, Turdus philomelos |
Abstract: | Aims To examine the use of the Breeding Bird Survey (BBS) in providing unbiased national population and habitat-specific density estimates of British birds. Methods Line transect data collected by volunteers in 1998 from 2287 1-km squares across the UK were analysed using distance sampling methods to calculate habitat-specific density and abundance estimates. For each species, the habitat-specific decline in detectability with distance from a transect line was modelled and applied at a regional level to incorporate variation in sampling intensity in different areas of the country. Results National population and density estimates calculated here were at a magnitude expected for at least seven species in this study. However, national population size estimates were higher than expected for Starling Sturnus vulgaris, House Sparrow Passer domesticus, Blackbird Turdus merula, Greenfinch Carduelis chloris, Jackdaw Corvus monedula, Whitethroat Sylvia communis, Woodpigeon Columba palumbus and Linnet Carduelis cannabina and lower than expected for Skylark Alauda arvensis, Dunnock Prunella modularis, Song Thrush Turdus philomelos and Corn Bunting Miliaria calandra. These differences are likely to be related to differences in sampling design and survey methods. For example, Starling, House Sparrow, Blackbird, Jackdaw, Greenfinch and Wood Pigeon, which have considerable populations in urban areas, were undoubtedly underestimated by the Common Birds Census (CBC). The counts of species that flock during the breeding season, or are not strongly territorial (e.g. Linnet, Jackdaw and Wood Pigeon) could be biased if detectability is strongly related to flock size. National population estimates of Skylark and Corn Bunting are lower than those based on CBC, but higher, or similar, to targeted national surveys of these species. Possible reasons for the differences between these estimates are considered. Conclusions This study highlights the strength of the BBS over previous data sources in producing national estimates of density and abundance at the habitat and national level. More research on the sex ratio and status of birds counted during surveys, and on the reliability of the detectability functions derived from distance sampling is needed to improve the interpretation of population estimates derived from BBS data.Aims To examine the use of the Breeding Bird Survey (BBS) in providing unbiased national population and habitat-specific density estimates of British birds. Methods Line transect data collected by volunteers in 1998 from 2287 1-km squares across the UK were analysed using distance sampling methods to calculate habitat-specific density and abundance estimates. For each species, the habitat-specific decline in detectability with distance from a transect line was modelled and applied at a regional level to incorporate variation in sampling intensity in different areas of the country. Results National population and density estimates calculated here were at a magnitude expected for at least seven species in this study. However, national population size estimates were higher than expected for Starling Sturnus vulgaris, House Sparrow Passer domesticus, Blackbird Turdus merula, Greenfinch Carduelis chloris, Jackdaw Corvus monedula, Whitethroat Sylvia communis, Woodpigeon Columba palumbus and Linnet Carduelis cannabina and lower than expected for Skylark Alauda arvensis, Dunnock Prunella modularis, Song Thrush Turdus philomelos and Corn Bunting Miliaria calandra. These differences are likely to be related to differences in sampling design and survey methods. For example, Starling, House Sparrow, Blackbird, Jackdaw, Greenfinch and Wood Pigeon, which have considerable populations in urban areas, were undoubtedly underestimated by the Common Birds Census (CBC). The counts of species that flock during the breeding season, or are not strongly territorial (e.g. Linnet, Jackdaw and Wood Pigeon) could be biased if detectability is strongly related to flock size. National population estimates of Skylark and Corn Bunting are lower than those based on CBC, but higher, or similar, to targeted national surveys of these species. Possible reasons for the differences between these estimates are considered. Conclusions This study highlights the strength of the BBS over previous data sources in producing national estimates of density and abundance at the habitat and national level. More research on the sex ratio and status of birds counted during surveys, and on the reliability of the detectability functions derived from distance sampling is needed to improve the interpretation of population estimates derived from BBS data. |
URL: | http://www.tandfonline.com/doi/abs/10.1080/00063650509461373 |
Short Title: | Bird Study |
Taxonomic name:
Alauda (Birds), Alauda arvensis (Birds), Alauda arvensis (Birds), Alaudidae (Birds), Carduelis (Birds), Chloris (Birds), Chloris chloris (Birds), Coloeus (Birds), Coloeus monedula (Birds), Columba (Birds), Columba palumbus (Birds), Columba Palumbus (Birds), Columbidae (Birds), Corvidae (Birds), Corvus (Birds), Corvus Monedula (Birds), Emberiza (Birds), Emberiza calandra (Birds), Emberiza Calandra (Birds), Emberiza godlewskii (Birds), Emberiza Godlewskii (Birds), Emberizidae (Birds), Fringillidae (Birds), Linaria (Birds), Linaria cannabina (Birds), Passer (Birds), Passer domesticus (Birds), Passeridae (Birds), Prunella (Birds), Prunellidae (Birds), Sturnidae (Birds), Sturnus (Birds), Sturnus vulgaris (Birds), Sturnus vulgaris (Birds), Sylvia (Birds), Sylvia communis (Birds), Sylvia communis (Birds), Sylviidae (Birds), Turdidae (Birds), Turdus (Birds), Turdus maximus (Birds), Turdus merula (Birds), Turdus Merula (Birds), Turdus philomelos (Birds), Turdus philomelos (Birds)