Taking the time to watch birds and butterflies as they fly around is a large part of the enjoyment of a garden. And particularly so for bluebirds because of their distinctive color and tuneful song. This article by Rhiannon Crain which I found on the Houzz website describes the three different species of bluebirds found in North America and then suggests ways you can encourage them to visit your garden.

For many people in the birding world, the joy of a bluebird may be unparalleled. From their magnificent plumage and melodic song to the uplifting thrill of their recovering population, no other bird inspires art, music or citizen-science participation quite like our native bluebirds. With a little help, the bluebird of happiness can be a part of your backyard too.
See more at Houzz