by Sarah Kishler
Cliff swallows (Petrochedlidon pyrrhonota), also known as “eave swallows,” are noted for the jug-like nests that they build with mud, clay, grass, and feathers. Cliff swallows used to nest mostly on overhanging cliffs, but as land became more developed, they began a successful switch to manmade structures such as buildings, bridges, and overpasses. This demonstrated ability to adapt has helped the cliff swallow to expand in numbers and range (the species can be found in most parts of North America in the summer—in the winter, it migrates to South America).
Cliff swallow colonies consist of somewhere between 800 and 1,00 monogamous pairs. Both sexes build nests and feed the young. The colony serves as a valuable resource for birds who are having a hard time foraging for their offspring. These swallows will find out which birds are finding food for their young and then follow them to see where the food source is.
Like other swallows, the cliff swallow catches and feeds on insects while in flight. This is a help to farmers because many of these insects are harmful to crops. They sometimes eat berries and fruits as well.
The adult cliff swallow sports a blue-black crown, a white forehead, a tiny black bill, brown sides of the neck, blue-black upper-parts, and white under-parts. The tail is squared with a small cleft. Both sexes are alike in plumage.
Cliff swallows can be told from most other species of swallow by its pale rump. The species most similar in appearance to the cliff swallow is the cave swallow, which also has a pale rump. Cave swallows have darker foreheads and lighter throats and are not found in California.