Cave SwallowPetrochelidon fulva
As recently as the 1960s, this was a rare bird in the United States. It nested only in a few southwestern caves, plastering its cuplike mud nest against the walls in the dimly lit interior. Since then it has "learned" to nest in artificial sites, in culverts and under bridges, and it has become a common summer bird across much of Texas and southern New Mexico (with an outlying colony in Florida). In some places, Cave Swallows may actively compete with Cliff Swallows for these artificial nest sites.