Animalia, Aves, Chordata, Hirundinidae, May, North America, Passeriformes, T. bicolor, Tachycineta, Tachycineta bicolor, US, USA, Wisconsin, adult, adults, beautiful, bicolored, bird, bird house, birdhouse, birds, blue, blue-green, breed, breeding, cavity nest, copulate, copulating, couple, fauna, feathers, female, iridescent, lichen, male, mate, mates, mating, natural, nature, north american, north woods, northern, northwoods, outdoors, pair, sex, sexual copulation, song bird, songbird, spring, spring time, springtime, striking, swallow, tree swallow, tree swallows copulating, wild, wildlife