Final call for records for Bird Atlas 2007–11

With over 9 million records in the Bird Atlas database you would think that we have all the records we need, wouldn't you? Coverage has been excellent and the provisional maps are looking great but there are still some gaps — can you help?

The distribution maps are comprehensive for the majority of species but we are probably missing some confirmed breeding records of scarcer species such as Hawfinch and Hobby. Even for very common and widespread species we are lacking confirmed breeding records; there are 121 10-km squares where Wren has not been confirmed breeding. These are mostly in the remoter parts of Scotland and in Ireland where there have been fewer visits made by atlasers, but if you live in SP55 (just south of Daventry), SK58 (Anston area) or SK87 (Newton-on-Trent) can you add a record to confirm Wren breeding? We welcome records of birds in the winter (November to February) and the breeding season (April to July) from within the period 1 November 2007 to the end of the breeding season in 2011. Any early or late breeding records from March, August or September can also be submitted. Records can be submitted online at www.birdatlas.net and there is also a very simple upload system for uploading records from an Excel spreadsheet.

The provisional results are showing many interesting things. There are gains and losses for the species we might expect, but also some surprises. Grasshopper Warbler has expanded its range in Scotland, Ireland and parts of western and northern England but has failed to regain ground in southeast Britain where we saw such huge losses between the 1968–72 and 1988–91 Atlases. Did you know that Black Swan has been recorded with breeding evidence in over 100 10-km squares and confirmed breeding in 34 10-km squares? For Yellow Wagtail we've documented the losses you might expect. If you're a birder in England you've surely noticed the losses in your local area. The distribution map shows that the breeding range is now mainly in central, eastern and northeastern England. Even within East Anglia, an area you might expect to be good for Yellow Wagtail, there are big gaps. There are very few records in Wales, Scotland and Ireland. Looking at the change map since the 1988–91 Atlas you'll see the huge losses in northwestern England, but also losses in southeast England, around the Somerset Levels and in East Anglia. Perhaps you have a record of breeding Yellow Wagtail that might fill in a gap?

Breeding distribution of Yellow Wagtail. Each dot represents a 10-km square. Three sizes of dot indicate possible (small), probable (medium) and confirmed (large) breeding. (BTO).

Change in Yellow Wagtail distribution between 1988–91 and 2008–11. Upward pointing orange triangles are gains, downward pointing open triangles are losses. (BTO).

We've been able to analyse the data and produce some measure of change in relative abundance over the last 20 years. Both the 1988–91 Atlas and Bird Atlas 2007–11 asked volunteers to make timed counts in tetrads (2×2 km squares) so we have information on tetrad occupancy within a 10-km square in both atlas periods. Looking at the number of tetrads a species was recorded in (and taking into account variation in effort between the two atlas periods) we can work out whether the number of occupied tetrads within a 10-km square square has increased or decreased over the last 20 years. The results for some species are striking and give us a far greater understanding of changes that may be taking place. Take Willow Warbler for example; a look at the breeding season distribution map will show that is it widespread across Britain and Ireland (recorded in nearly every 10-km square) but when we look at the change in tetrad occupancy we see a striking north and west/south and east divide. So although still widespread at a broad scale, there are fewer tetrads occupied in the southeast of Britain now than there were 20 years ago and more tetrads occupied in northern Britain and in Ireland. These patterns link in quite nicely with populations trends measured by the Breeding Bird Survey in the UK and the Countryside Bird Survey in the Republic of Ireland.

Change in relative abundance of Willow Warbler between 1988–91 and 2008–11. Squares shaded grey/black show a decline in tetrad occupancy (the darker the colour the greater the loss) and squares shaded red/pink show an increase in tetrad occupancy (the darker the colour the greater the gain). (BTO).

Now that fieldwork is over for Bird Atlas 2007–11 we're keen to get all records in promptly and begin the exciting task of looking at the data in details and writing the book that will follow. Please have a look through your notebook or scan your electronic database for records that might be useful. If you want a list of species recorded in the 10-km square where you live so you can see where the gaps are please get in touch. We're asking that all records are submitted by the end of December so there is a month left for you to contribute and make a difference to the Atlas. Thank you to everyone that has submitted records to the Atlas.