I subscribe to about every birding magazine there is, and, yes, they do have articles about bird house dimensions, but since they have no URL, I can't direct you to these sources. Here is something you should know, though:
The dimension of the hole is CRUCIAL in determining which bird species will use the house. If it's too big, some cavity nesters won't use it. And for good reason. Some predatory birds, such as American kestrels, will slide into a too-big hole and eat the chicks.
It's a tough question, though, because all the books list PRECISE dimensions for each cavity-nesting species.
My best advice to you is to try a few different hole dimensions and see which cavity-nesters explore it. Don't be discouraged if no birds use it for a year or two. It often takes them awhile before they decide to give it a go.
As for your jays, you live right on the border between two jay species: the western scrub-jay and the Steller's jay (which looks like a blue jay but wth a black head and crest).
As much as I love jays, both these species are notorious nest robbers. They will kill and eat nestlings of other species when given an opportunity. That said, I would make sure the hole dimension on your bird house is TOO SMALL for a jay to enter.
Say what you will, but it's just not a pretty sight to watch a jay kill and devour a songbird nestling.
Good luck and keep me posted!
In one of the houses I built for the chickadees, I noticed that a bird had begun to build a nest in it. Strange tho, the nesting material was all twigs which is indicative of a dove nest. However, the hole is too small for a dove...and I’ve never heard of a dove using a birdhouse. I think the hole is only about 1 3/8” in diameter. Any thoughts on what may have started the nest?
Nature can indeed be cruel. Just ask that guy that studied grizzlies to his detriment.
Thanks for the reply, I guess the library is my next stop for plans. It's good that I have the time. I'll let you know how it goes.