Bird Atlas 2007 - 11

Bird Atlas 2007-11 is a huge and exciting project being run by the British Trust for Ornithology (BTO) that will map the abundance and distribution of birds in Britain and Ireland during the breeding season and winter. It will be fascinating to look at the changes in distribution since the last breeding and wintering atlases.  There have been two previous breeding atlases (1968-72 and 1988-91) and just one previous winter atlas (1981-84). Have Buzzards continued to expand? Have Ravens spread eastwards? Have Wood Warblers disappeared from our woodlands? Where do we find Snipe in the winter? Are Siskins in the same places in summer and winter? It’s amazing to think that Little Egret was only recorded as a non-breeding visitor in three 10-km squares in the 1988-91 Atlas and now they are breeding in many counties, including Berkshire.

                      Winter increase                                                                       Breeding population

In Berkshire we are taking the opportunity to update our county atlas at the same time as the national atlas work is taking place. Surveying for our last (and only) county atlas occurred at the end of the 1980’s and there are likely to have been many changes during the intervening years. Apart from breeding bird distribution, the new county atlas will, for the first time, map wintering bird distribution; map relative abundance across the county; attempt to explain changes in distribution and estimate overall population numbers. In short, an exceptionally important work of reference on the county’s ornithology!

Both atlases will include winter distribution and breeding season data and the survey work for these will be spread over four years starting in November 2007. Although the county atlas will be based on tetrads (2km x 2km squares) and the national one on 10km squares, BTO have offered to collect and process all our records to a tetrad level and we therefore intend to use the BTO survey method and tools for both atlases, extending the coverage where necessary to gather the extra information required for the Berkshire atlas. By effectively combining the two surveys we will considerably reduce our data collection and analysis effort.

Berkshire records and offers of help within the county are of particular interest for us but from November we need all your records – whatever you see, whenever it is, wherever you are! There are two components to the fieldwork: Timed Tetrad Visits (TTVs) and Roving Recorders. TTVs involve two visits in the summer and two in the winter to a tetrad (2 km x 2 km square). Each visit is for a minimum of one hour (although we would prefer two) and the idea is to record species you see and hear along with their numbers, so we can calculate the relative abundance of species in the 2-km squares. Of equal importance are Roving Recorders who make general birdwatching visits to 2km squares where the aim is to compile a species list of everything you see and hear. An important part of a Rover’s task is to try to gather evidence of breeding as they go along (three levels – Possible, Probable and Definite).

With over 450 tetrads in Berkshire there is a lot of counting and recording to be done! Whatever your level of birdwatching skill you should be able to contribute something to this project; please get in touch with me if you are able to help in any way. If you have access to the internet, you can find a lot more information about the national atlas at www.birdatlas.net which explains the methods and strategy as well as how to stake a claim for a tetrad and submit your data when the time comes!

Chris Robinson

(Berkshire BTO Rep and Berkshire Bird Atlas Group Chairman)

Tel: 01491 671420; Email: berks_bto_rep@btinternet.com