The British Trust for Ornithology’s Breeding Bird Survey is the most important of the long-term monitoring schemes for common birds in the United Kingdom and underlies much of the “trends” data which are frequently quoted. National results are published in
and also form part of the data underlying
Ordnance Survey 1-km squares are selected nationally by stratified random sampling – which is designed to ensure that the coverage is representative of the full range of habitats – and, ideally, are surveyed every year. Squares are made available by the BTO for allocation to regions such as Durham in small batches, which need to be more-or-less all taken up before an additional set can be requested.
Anyone interested in taking part in the survey is advised to look at the full information for BBS available on the BTO website.
At present the BTO Durham Region has an allocation of 57 squares, but only 33 of these were covered in 2019. An increase in coverage would be useful to enable regional trends in population to be detected more easily. The squares which are available and without observers for 2021 are shown below.
The 1-km square reference is a hotlink which should bring up the 1:50,000 O.S. map in the Geograph website; clicking on that map should display the larger-scale 1:25,000 map of that square.