The Lefurge Nature Preserve has several bird houses scattered around and some are occupied by these blue headed birds. I don’t know their real name but I do know they are sometimes aggressive.
A few of the bird homes are near the starting trail so you have to pass by and certain times of the summer these birds are particularly protective of them. When walking by they dive bomb you, pulling up just before impact. My reaction is always to duck and run.
The Mystery Meat 