Migratory bird numbers fall in Britain despite last year’s warm spring

British Trust for Ornithology says 2025 breeding season was especially disastrous for warbler species

After a mild, wet and stormy winter in the UK, spring 2025 was one of the warmest and driest ever, while the summer was the hottest since records began, most particularly in England and Wales.

Good news, you might think, for migratory birds – especially for eight species of warblers that travel here from their winter quarters in Africa. Yet according to data from bird ringers , collated by the British Trust for Ornithology (BTO), last year’s breeding season was pretty disastrous.

Four species – willow warbler, blackcap, garden warbler and common whitethroat – showed significant falls. Three others – sedge and reed warblers and lesser whitethroat – also declined, though less seriously. Only the chiffchaff, which winters closer to home in north Africa and Iberia, with some staying put in southern Britain, showed a rise in numbers.

The BTO’s other major annual study, the breeding bird survey , revealed similarly mixed fortunes, notably for pigeons and doves. While woodpigeon and stock dove numbers continued to rise, the two smaller species, collared and turtle doves, continued their rapid decline.

Care needs to be taken when ascribing rises or falls in bird populations to the weather conditions in any particular year, because many other factors, including habitat loss at home and abroad, may be involved. But with the climate crisis leading to more extreme weather events, vigilance is required. Hence the crucial importance of the work of BTO staff and volunteers.