Guide to Boreal Birds
Swallow-like Birds Overview
The name "Rough-winged" refers to tiny hooklets on the outer vane (flat part of a feather) near the end of the shaft of the outer primary feathers. The function of these hooks, visible only under a magnifying glass and found also in an unrelated group of African swallows, is unknown. Unlike the Bank Swallow, Rough-wings do not usually dig their own nesting burrows but use ready-made nesting sites along streams. Thus they do not nest in large colonies like the Bank Swallow, although occasionally a few pairs may be found close together.
Description
5-5 3/4" (13-15 cm). Pale brown above, white below, with dingy brown throat. Bank Swallow is similar, but smaller, and has white throat and brown breast band.
Voice
A low, unmusical br-r-ret, more drawn out than the call of the Bank Swallow and often doubled.
Nesting
4-8 white eggs in a burrow or cavity; will utilize ready-made cavities in bridges, culverts, or other streamside masonry. Not highly colonial; often nests singly.
Habitat
Riverbanks. Prefers drier sites than the Bank Swallow.
Range/Migration
Breeds from southeastern Alaska and southern Canada southward throughout United States. Winters north to southern California, Gulf Coast, and southern Florida.