breeding abundance in
Britain and Ireland
The BTO has completed three Atlas projects, each the result of four years’ fieldwork: 1968–72, 1988–91 and 2008–11. These Atlases have been mapped against 10km squares based on the OS National Grid.
![](https://cambridgeshirebirdringing.org/wp-content/uploads/2018/12/Spotted-Flycatcher2-1024x717.jpg)
relative abundance over time
Relative abundance measures were only recorded for the two latest Atlases; this allows comparison after a twenty year interval. The 2008-11 Atlas shows that current densities are generally highest in the north and west – excluding the highest upland areas – and lowest in the east and south-east of England and along the western coast of Ireland.
![](https://cambridgeshirebirdringing.org/wp-content/uploads/2018/12/2008-abundance-746x1024.jpg)
The relative abundance change map (2008-11 against 1988-91 as below) shows declines, some very marked, throughout England and lowland Scotland, with maybe just a suggestion that the species may be faring better in north-west Scotland and southern Ireland.
![](https://cambridgeshirebirdringing.org/wp-content/uploads/2018/12/Abundance-change-746x1024.jpg)
This trend, if it is one, is shared with other long-distant migrants such as Willow Warbler, House Martin and Cuckoo and may be associated with changes in climate, mixed vs arable farming and/or differential rates of decline in invertebrate densities. It may also be related to migration strategies by sub-populations: differential timing, routes, stopovers and/or wintering areas.
As a result of these declines, the species is now Red-listed as a bird of increasing conservation concern. Similar, if more moderate, declines have been recorded across the rest of Europe.
[The text and maps above are derived from the BTO’s
Bird Atlas 2007-11
The breeding and wintering birds of Britain and Ireland
(Dawn Balmer et al. 2013).]