Crossbills, Distribution survey in Great Britain, 1995-2005

Quality Control

These data have been gathered by trained field-workers and the data are of a high quality. These data have been mapped and checked for sensitivities and typographical/geographical errors

Method steps

1. The study was carried out from 1995-2005 during January and April when it can be reasonably assumed Crossbills are either in a territory or breeding. All 10 km squares north of 56 degrees and 50 minutes north, containing more than 20% woodland, were surveyed. In general, the larger woods were searched until at least 1 crossbill had been recorded. Multiple recordings from the same 10KM grid square were restricted to a few squares. Crossbills were lured using a characteristic excitement call broadcast from mini speakers. Lured birds are usually vocal and both flight and excitement calls can be tape recorded using a directional microphone. Sonograms were made from the tape recordings allowing species identification.

All the 10 km squares north of 56 degrees and 50 minutes north, containing more than 20% woodland, were surveyed. This dataset includes some additional data collected in Wales and Eastern England which were not used in the published paper