Q: We have several bird houses located on 4″ x 4″ posts in our yard. Unfortunately a snake was able to climb to one house and ate the baby bluebirds. Do you have any prevention suggestions?
A: A slick metal pipe is a better birdhouse mount but I know you’d rather not replace the wooden posts at this point. Try making a sheet metal cone, using metal snips to shape the metal so the eighteen inch wide mouth is pointed toward the earth. I don’t think a snake could get around that.
Birdhouse Guard (scroll down half-way)