Adapted from Jim Conrad's online book A Birding Trip through Mexico, This excerpt from "The Cactus Desert at Zapotitlán" in southeastern Puebla state
SWALLOWS DAWN TO DUSK
In the canyon's bottom, around the campsite and along the stream, no bird is more conspicuous for most of every day than the Northern Rough-winged Swallow. Especially during the hours before dusk, six to eight wing up and down the stream, again and again, always softly calling their burry brrrtt brrrtt brrrtts.
These are plain little creatures, gray-brown on top and pale below. As often is the case with plain-looking beings, however, they enjoy a compensatory elegance: Their streamlined bodies could not more gracefully cut through the air. It is simply a delight to watch them.
In 1934, John A. Gillespie caught a male Rough-winged Swallow at its nest near Glenolden, Pennsylvania and took it by automobile to Milford, Delaware, 52 kilometers away (32.5 miles). Driving back immediately after releasing the bird, he arrived at the bird's Glenolden nesting place to find the bird already returned and helping its mate feed five young birds.
Some swallow species nest in such large colonies that when the young birds return home sometimes they wander into the wrong burrows. Adults of such communal species frequently reject strayed younglings and the young birds may die of starvation. In contrast, Northern Rough-winged Swallows are solitary nesters, and they don't discriminate between their own offspring and those of others placed in their nests.