Some days I feel that this photo sums up the modern world. Try to listen every so often … you might learn something.
The All About Birds page on Tree Swallows (Tachycineta bicolor) says they are:
Handsome aerialists with deep-blue iridescent backs and clean white fronts, Tree Swallows are a familiar sight in summer fields and wetlands across northern North America. They chase after flying insects with acrobatic twists and turns, their steely blue-green feathers flashing in the sunlight. Tree Swallows nest in tree cavities; they also readily take up residence in nest boxes. This habit has allowed scientists to study their breeding biology in detail, and makes them a great addition to many a homeowner’s yard or field.
…Tree Swallows feed on small, aerial insects that they catch in their mouths during acrobatic flight. After breeding, Tree Swallows gather in large flocks to molt and migrate. In the nonbreeding season, they form huge communal roosts.
More birds on Michigan in Pictures.