Unusual Barn Swallow Nest Placement in Southeastern Oregon

—Barn Swallows (Hirundo rustica) historically nested along cliffs, in caves, and in other natural situations. Currently, nearly all reported nests of this species are on walls and beams of bridges, buildings, and other human-derived structures. Both natural and man-made nest sites typically share one thing in common: a horizontal surface for nest attachment. We describe a Barn Swallow nest that was constructed on a branch overhanging a river in southeastern Oregon. This is the first documented occurrence of this behavior by Barn Swallows and we believe it to be the result of high competition for a limited number of suitable nest sites in the study area. Received 23 February 2006. Accepted 1 August 2006. The Barn Swallow (Hirundo rustica) is perhaps the most well-studied species of swallow in the world. It breeds throughout the northern hemisphere, including much of North America. Historically this species nested in caves and on cliffs but now nests primarily on artificial structures (i.e., eaves, bridges, etc.). A search of the literature regarding nest placement of this species indicated that nests away from vertical structures (both natural and artificial) are rarely reported, if at all (Speich et al. 1986). Nest architecture is perceived to be a relatively fixed trait with an underlying genetic basis, as studies have shown its usefulness in phylogenetic analyses (Winkler and Sheldon 1993, Zyskowski and Prum 1999). We report on observations of two atypically constructed nests of Barn Swallows in southeastern Oregon.