The Cave Swallow (Petrochelidon fulva), first discovered breeding in Texas in 1915, originally was thought to be confined to sinkholes in central and western Texas. During our survey of bridges in Brazos County, Texas, we discovered Cave Swallows modify and use old Barn Swallow (Hirundo rustica) nests, a previously unreported behavior. The presence of Barn Swallows (or old Barn Swallow nests) may facilitate colonization of new areas by Cave Swallows.