Tree swallow (male)

Tree swallows will use natural and pre-existing holes for nesting when they can. The male has glossy blue-green upperparts and white underparts and cheeks. Wings and tail are blackish with underwing coverts being gray (pics 4 and 5). It is possible the bird in pics 4 and 5 is a female. Some females have as much blue as males. Small dark bill and black eyes.