I've loads of custys with this happening to them & it's on the increase. Don't know what's happening but prior to about 3 years ago I'd never witnessed this happen at all. It happened to ME on our own home just yesterday for the first time ever!!!

6am & a massive crow banging the hell out of my kitchen window with it's beak!!
They also sometimes strip the sealing mastic out from around the window frame & I've one customer who has to put socks on his windscreen wipers as they strip them of the rubber every day!!
It's weird.
