What’s involved?

During the breeding season, CBS counters record all birds seen and heard during two early morning walks in pre-assigned 1km grid squares. Two visits are made to the site – one in early summer (April to mid-May) and the second about 4 weeks later (mid-May to end June). As many birds are detected first by sound (and often not seen) it is helpful to be able to identify birds by song and call as well as sight. Survey squares occur in a broad range of habitats across every county, from upland blanket bog to lowland farmland and woodland.

Why do we count breeding countryside birds?

CBS has served to show that populations of our common and widespread birds are continually changing. While most species are quite stable, some such as Goldfinch and Blackcap have increased substantially over the last 20 years. Some species such as Stonechat and Grey Wagtail have been shown to be prone to big fluctuations, especially after severe winters, while others including Kestrel, Skylark and Stock Dove are showing worrying declines. Such declines can be noted anecdotally, however this survey aims to detect and quantify such changes using robust, scientific but user-friendly methods. Over time, reasons for decline may be identified and there will be opportunities to provide advice to help reverse such trends.