The Western Bluebird and the Eastern Bluebird would seem to be another east-west species pair,
like the Black-headed and Rose-breasted Grosbeaks, the Lazuli and Indigo Buntings, the Western and
Eastern Meadowlarks, and the Spotted and Eastern Towhees, But, unlike those pairs, their songs and singing
are dissimilar. The Western above was dawnsinging from the top of a tree, after previously giving the same
kind of performance in flight. He pumps out rather simple notes at a constant rate, without pause, for minutes on end,
whereas the Eastern Bluebird
combines a few complex notes into a song, then pauses before giving another one. The Western actually sounds much
more like the Mountain Bluebird than the Eastern. And as you will recall, the Eastern sings more like a Siberian
Rubythroat than its own close relative.