The Barn Swallow is the most abundant and widely distributed swallow species in the world.
They used to nest in caves throughout North America but now they build their nests almost exclusively on human made structures. Today the only North American Barn Swallow population that still regularly uses caves as nest sites occurs in the Channel Islands off the California coast.
I photographed this one in a wetland area in Plymouth Minnesota.

There are legends that the Barn Swallow got it's forked tail because it stole fire from the gods to bring to people. An angry deity hurled a firebrand (some say fire arrows) at the swallow, singeing away it's middle tail feather.