05/02/2024
Barn Swallows are beginning their spring migration here in Wisconsin, prompting a curious question: What did these birds use for nest sites before barns were around?
Barn swallows are called "barn" swallows because they often choose to nest in and around barns, creating their nest from mud on the rafters or overhangs. These resilient little birds have shown remarkable adaptations to human development and can also nest in other manmade structures such as sheds, bridges, and houses.
Before barns became widespread, barn swallows nested in natural habitats such as caves, cliffs, and rocky overhangs. These natural structures provided similar sheltered environments that barns offer - protection from predators and the elements, as well as suitable nesting sites. Barn swallows have historically utilized a variety of habitats for nesting, but the availability of human-made structures like barns and bridges has greatly expanded their nesting options and contributed to their widespread distribution in many parts of the world.
Barn swallows construct their nests using mud, which they collect with their bills while in flight. They mix the mud with plants, mostly grasses, and feathers to create a sticky, pliable substance. Using their beaks and feet, they shape the mud mixture into a cup-shaped nest, typically attached to a vertical surface such as the rafters or walls of a barn.
