by Erik » Fri Nov 13, 2009 10:59 am
Where I live we don't have that kind of roofing, but I can imaging that in the past (or present) those kind of shingles can have been treated with wood preservatives? Or are cedar shingles not easy affected by fungi or beetles? Anyway whenever you recycle wood for bat houses, make sure they have been treated with wood preservatives that are toxic for mammals.
For example, until the late 90's PCP (Pentachloorphenol) was a legal wood preservative in Europe. To protect the wood in the attics historical buildings (farm buildings, barns, churches, monasteries against damage by fungi and beetles PCP has been used. Sometimes wooden beams in the church were impregnated with PCP's, but with renovations parts of beams and roofs were replaced by new impregnated wood.
It was banned in the late '90's because it very toxic to many animals. Recently bat researcher have found that, even after decades, wood treated with PCP is still killing bats. Probably the bats get affected by roosting on the wooden beams or in between shelves and boarding. They take in the poison trough the skin or get the poison on their skin and hairs in their mouth while grooming. It's accumulates in the fat and fat milk. Hibernating bats (burning fat while waking up once in a while) and pups are especially at risk.
Erik