First off, you need to keep your cat indoors. If you are worried about it having scared off the blues, think of what it could do to newly fledged birds that cannot fly well.
Second if you think you don’t have coons, think again. They are pretty much everywhere in the US, they hunt at night so often you do not see them. Please don’t put the house up on anything that a predator could climb up and set the birds up for failure. Mount it on a piece of 1″ conduit with a wobbling stovepipe predator baffle and place at least 15 feet away from anything a predator could jump from.
Donna in WI