A swallow with almost worldwide distribution, bank swallows (Riparia riparia) that summer and breed in North America winter in South America and the Pacific Slope of Mexico. A very social bird, bank swallows nest in colonies of ten to as many as 2,000 nests. They will huddle together when temperatures become extremely cold.
Bank swallows nest in natural bluffs and eroding stream banks, usually in areas where the soil is loose. They will also utilize man-made sites such as road cuts or quarries. Bank swallows prefer to build their nests high up or in the upper part of a bank to deter predators.
The male bank swallow uses his bill, feet and wings to dig a burrow perpendicular to the ground, tunneling upward at the end to form a nest chamber. The nest can be located up to two feet into the side of the bank. Once the burrows are dug the females come and select a male and nest site. The female builds the nest itself, a mat of grasses, rootlets, leaves and straw. After incubating for 13 to 16 days, the 2 to 6 white eggs hatch. The chicks are naked with a bit of grey down. The nestlings fledge in 18 to 24 days.
Bank swallows are white underneath and brown on top with a distinctive dark band across the chest. The bill is small, the wings are long and the tail is slightly forked.
A bank swallow’s diet consists almost exclusively of flying or jumping insects which are almost always taken while in flight. Occasionally bank swallows will pick an insect off of the ground or water surface.
Each summer a colony of bank swallows nest in a natural bank along Highway 299W near Fall River Mills CA where these pictures were taken.