Just now, July 14th, I observed the first of season Calliope in my yard. Lordy they are tiny things. At first, watching the little thing hover over the feeder next to another bird that I could barely see, I wondered if it was sparing with a small oriole! No, of course not...but the other hummingbird seemed twice as big, by comparrison. (my photo here doesn't show what I mean at all! The other bird turned out to be a Rufus hummer...which IS nearly twice as big as the little guy I observed!)
The Calliope Hummingbird is the smallest bird in North America (about 1/3 the size of our smallest warblers) and the smallest, long-distance migrant in the world...breeding in the Northwestern US and Canada and spending winters in Mexico.