Family: (Hirundinidae) Swallows
Profile by Aidan Healey: The Cave Swallow is an increasingly common species in the greater Houston area. At first glance, the Cave Swallow appears very similar to the closely related (and more abundant) Cliff Swallow. Both species are generally light below and darker above, both species have a buffy rump patch that is easily visible in flight, and both species are often seen foraging for insects in open areas. However, the Cave Swallow is slightly smaller and, if you look closely, the Cave Swallow also has a lighter buffy throat and a darker forehead than does the Cliff Swallow.
The Cave Swallow is a colonial nesting species, and colonies historically nested inside the entrances of caves. However, as their range has expanded into areas where caves are not as readily available, Cave Swallows have begun building their nests in culverts and on the underside of bridges. Cave Swallows use mud to build their cup-shaped nests, which are generally more open on top than the jug-like nests built by Cliff Swallows.
Cornell Lab of Ornithology