Concrete “pillboxes” built to defend against a feared World War II invasion are being converted into artificial caves to provide homes for hibernating bats in southeastern England, BBC News reports.
Volunteers from the Stour Valley Countryside Project, a conservation organization, are working with a number of partners to convert 10 of the 66-year-old gun emplacements into bat-hibernation sites. The project carries a price tag of 5,000 pounds (US $8,735).
Project Landscape and Biodiversity Officer Peter Ennis told BBC that the pillboxes, because they are either buried or very substantial, maintain a “fairly constant temperature and, in the winter, act rather like a cave.” Caves, he said, are in short supply in the area.
“Our aim,” said Sudbury Common Lands Ranger Adrian Walters, “is to provide diverse wildlife habitats on the Sudbury riverside. The conversion of the pillboxes will add to that diversity and, if successful, provide secure winter hibernacula and further summer roosting sites for the bats that find rich hunting grounds over the traditional pastoral landscape.”
The Project said that the United Kingdom is home to more bat species than any other group of mammals, and bats have suffered a serious decline in recent years due mostly to lost habitats.
Ennis said the conversion is designed to make sure the pillboxes meet hibernating bats’ needs for constant air temperature and high humidity. The shelters will be fitted with steel gates to keep people from disturbing the bats, and most of the old gun ports will be bricked up to help maintain stable temperatures. The smooth interior walls will be fitted with special bricks and blocks to provide a variety of nooks and crannies for the bats.
He told BBC that dataloggers will be installed in the bunkers to track temperature and humidity conditions and determine whether additional modifications are needed.
The conservationists hope the new hibernacula will attract western barbastelles (Barbastella barbastellus), Natterer’s myotis (Myotis nattereri), Daubenton’s free-tailed bats (Myopterus daubentonli) and brown big-eared bats (Plecotus auritus), all of which are known to feed over the River Stour and adjacent pastures.