This morning while atlasing in Patapsco State Park, I encountered
Rough-winged swallows apparently using abandoned semi-trailers for nesting
sites.  The trailers had several holes on the underside, rougly three inches
across.  Several birds were seen entering and exiting holes on the corner of
two separate trailers.  When I went for a closer look, the swallows became
quite agitated.  I saw no actual nest (it was rather dark!) and heard now
chicks.  Has anyone else ever noticed Rough-wings using trailers to nest?

Kurt Schwarz
HowCo