At the Billy Frank Jr National Wildlife Refuge, 26 April 2021 proved to be a five-swallow day—Erika and I saw Barn, Cliff, Tree, Violet-green, and this Northern Rough-winged swallow. Of these species, the rough-winged swallow is the least frequently seen. For one thing, this species can be difficult to identify—it lacks a breast band and sports and indistinct dark crown. Audubon first described this species, and even he initially did not realize he had a new species. This swallow is named for the tiny barbs that protrude from its outer wing feathers—barbs whose function remain a mystery.
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