About the survey

The BTO/JNCC/RSPB Breeding Bird Survey (BBS) is the main scheme for monitoring the population changes of the UK’s common and widespread breeding birds, producing population trends for 119 bird and nine mammal species.  BBS is able to monitor the population changes thanks to the dedication of almost 3,000 volunteers who survey their randomly selected 1-km square each spring.

The survey involves a recce visit and two early-morning spring visits to an allocated 1-km square. Volunteers count all the birds seen or heard while walking two 1-km lines across the square, and record any nest counts for colonial nesting birds in the square. Volunteers can optionally record mammals and visit their square later in the season to survey for butterflies. There is the option to return data on paper, via field recording forms or to submit data on BBS-Online.

Code of Conduct

Volunteers must follow BTO’s Code of Conduct. This code applies to our staff, our members, and volunteers, including surveyors and participants in the Ringing and Nest Record Schemes, (hereafter referred to collectively as ‘staff and supporters’). It applies to all BTO activities, whether online (including meetings and events, telephone, letter, and email) or offline (any face-to-face interaction). We've also written some guidance for volunteer fieldworkers, which will help beginners in particular.

Read the latest BBS report

The Breeding Bird Survey started in 1994, and a report is produced every year containing population changes and other results from the scheme.

The 2025 Breeding Bird Survey Report highlights the varying fortunes of four of the UK’s widely monitored wild doves and pigeons. Whilst Stock Dove and Woodpigeon are faring well – Stock Dove has increased by over 40% in the last 10 years – the Turtle Dove decline shows no sign of abating, and Collared Dove has declined by around 40% since 2005. 

In Scotland, species of woodland and scrub – including Willow Warbler, Tree Pipit and Bullfinch – continue to increase, whilst populations further south in Britain are declining. In Wales, there are mixed fortunes. Woodland species such as Great Spotted Woodpecker have increased over threefold, and Nuthatch has increased by 55%, since 1995. Meanwhile, Curlew and Yellowhammer continue to decline. 

In Northern Ireland, which sees a change of baseline for monitoring trends from 1994 to 1996, the pattern of increasing Song Thrush (+75%, 1997–2024) and declining Mistle Thrush (-35%) highlights a UK-wide pattern for these two closely related species. Several species are not monitored by BBS in Northern Ireland, particularly farmland birds such as Kestrel, Curlew and Yellowhammer, and additional efforts are underway to improve monitoring in these declining species.

The 2025 season was also noteworthy for seeing a record number of 1-km squares being visited, with over 2,800 surveyors visiting 4,058 sites. We thank these skilled and dedicated volunteers who give their time to BBS and WBBS and make the monitoring of the UK’s breeding birds possible.

• Read the 2025 Breeding Bird Survey report