This Chaetura swift was flying in a loose congregation of hundreds of swallows, plus a few Chimney Swifts
at Mitchell Lake Audubon Center, Bexar County, Texas on October 17, 2005; for comparison I have interpsersed two photos of Vaux's Swift I photographed in Guatemala (most likely the migratory subspecies rather than the smaller, darker sedentary form from central Mexico):
