Homeowners renovating period properties are inadvertently destroying nesting sites for endangered birds in a quest to make their homes more energy efficient, conservationists have warned.
Swifts usually nest in holes near the roofs of properties, but renovation work is plugging these gaps and making it more difficult for the birds to breed.
The trend for converting old farm buildings into new homes is also destroying nesting sites for swallows, which prefer rural, abandoned buildings to breed.
People should install nesting boxes or ‘swift bricks’ around the roofs of homes when carrying out any renovation work to help save the birds, The Wildlife Trusts and the Royal Horticultural Society (RHS) urged this week.
Swifts and house martins have suffered huge declines in recent years and were added to the UK red list for endangered birds in December. Swift numbers alone have dropped 60 per cent over the last 25 years.
Helen Bostock, senior wildlife specialist at the RHS, said: “Anyone lucky enough to share their homes with nesting swallows, swifts or house martins will understand how magical these birds are. But also how vulnerable; with the numbers of those returning each summer dropping year on year.”
Alongside climate change and loss of insects, the loss of suitable nesting sites is a major driver of decline for all three birds.
Swallows and house martins make their nests using mud and grasses foraged from the ground. Swallows nest inside attics, farm buildings, and sheds, while house martins build their nests under the eaves of homes.
Renovation work can be harmful to house martins. Replacing timber soffits for plastic makes it difficult for their mud nests to stick and hold. Modern housing designs also tend to have shallow eaves unsuitable for nesting martins.
Swifts rarely touch the ground and nest in holes high in the eaves of buildings. Old, drafty homes used to be the perfect nesting spot for swifts, but in recent decades renovation works have seen builders plug gaps to improve energy efficiency.
Nest boxes can help all three species, said Ben Stammers of the North Wales Wildlife Trust. “With swallows you can just put a box inside a shed or a garage and it will help them,” he said. “Whereas for swifts it’s really to replace those gaps and holes that have been lost because people do work to renovate houses.”
The Wildlife Trusts is also campaigning for ‘swift bricks’ featuring nesting holes to be mandatory in all new build homes. Both swift bricks and boxes should face north or north east to stop nesting sites from overheating, and be at least five meters off the ground to protect against predators and help fledglings exit the nest successfully, The Wildlife Trusts said.
The public can also help swifts, swallows and martins by boosting insect life in their garden. Planting a ‘bog garden’ with plants like marsh-bedstraw and purple loosestrife will encourage frogs, dragonflies and insects, The RHS said, and provide house martins and swallows with materials to build their nests.