Short answer --- About 5 inches. :-) Blue Jays are ten to eleven inches long from tip of beak to tip of tail. The Western Bluebird is 5 and 1/2 inches long. The Scrub Jay has blue wings, tail and some on the upper part of the head. They show a lot of grey on the throat and breast. Stellar's Jays are mostly deep blue with a very prominent black topnotch. Both are noisy gregarious birds which tend to monopolize bird feeders and can be a real nuisance. Neither have any red on the breast. Western Bluebirds are about half the size of the jays - about the size of sparrows or slightly larger than Juncos. Bluebirds eat primarily insects and do not come to bird feeders where other birds are eating seeds or grain. The male Bluebird has very deep blue feathers on the head, wings, back and tail. Western Bluebirds have distinct rusty red breasts and usually have some rust color across the shoulder area.