Eastern Bluebirds are, in my opinion, not only the most interesting, but also one of the nicest looking birds in the U.S. The male Eastern Bluebird is much brighter in color than the female, and they both have blue on their wings, tail, head, and back. They have red on their breast except for the lower ½ which is white. Eastern bluebirds have black beaks and feet, and belong to the thrush family (same family as the American Robin).
There really isn't a note worthy size difference between the male and female. They are 6 ½-7 inches=17-18 cm tall, and weigh between 27-34 grams.