The red list of Britain’s most endangered birds has increased to 70 species with the swift, house martin, greenfinch and Bewick’s swan added to the latest assessment. The red list now accounts for more than a quarter of Britain’s 245 bird species, almost double the 36 species given the status of “highest conservation concern” in the first review 25 years ago. Birds are placed on the red list of the Birds of Conservation Concern report by a coalition of government wildlife bodies and bird charities either because their populations have severely declined in Britain or because they are considered under threat of global extinction. Swifts and house martins have been moved from the amber list to the red list because their numbers have more than halved – swift populations have fallen by 58% since 1995. They join other celebrated but now critically endangered long-distance migrants such as the nightingale and cuckoo, whose populations are plummeting owing to a combination of habitat loss, the disappearance of insect food sources and global heating both in British breeding grounds and along migratory routes to sub-Saharan Africa. Bewick’s swan is another endangered bird that undertakes an epic migration, flying between western Europe and the far north of Russia. It is under pressure from ingesting lead shot, loss of wetlands and climate changes causing shifts in its migrating patterns. The greenfinch is a familiar garden bird but has moved from the green list of least concern to the red list after its population slumped by 62% since 1993 following an outbreak of the disease trichomonosis. The infection spreads through contaminated food and water – sometimes on bird-feeders – and from birds feeding each other regurgitated food during the breeding season. While other endangered birds on the red list continue to decline (particularly “farmland” birds such as curlew and turtle dove) Britain’s largest aerial predator has moved off the red list. The white-tailed eagle is now on the amber list after a successful reintroduction programme that began in 1975, with the raptor spreading across north-west Scotland where there are now 123 breeding pairs. The species was hunted to extinction in 1916 so juvenile birds were first reintroduced from Norway. Offspring from the thriving Scottish population have been restored to the Isle of Wight, with the species likely to be returned to other coastal locations as historical persecution diminishes. Beccy Speight, the chief executive of the RSPB, one of the report partners, said the biggest-ever red list was more evidence that Britain’s wildlife was in freefall and not enough was being done to reverse declines. “We are seeing once common species such as swift and greenfinch now becoming rare,” she said. “As with our climate this really is the last chance saloon to halt and reverse the destruction of nature. We often know what action we need to take to change the situation, but we need to do much more, rapidly and at scale.” Dr Andrew Hoodless, the director of research at the Game and Wildlife Conservation Trust, said: “We need to better understand the effects of climate change on some species, as well as the impacts of changing habitats and food availability along migration routes and in wintering areas of sub-Saharan African migrants. For many red-listed species, however, improving breeding success in the UK is vital – we can and must make real and immediate improvements to this through better engagement with UK farmers, land managers and gamekeepers to encourage adoption of effective packages of conservation measures.” One small way people can help the house martin is to erect artificial nest cups under the eaves of homes, according to Juliet Vickery, the chief executive of the British Trust for Ornithology. She said: “It is both sad and shocking to think that the house martin, a bird that often, literally, makes its home under our roof, has become red-listed.”