Violet-green Swallow, Fernhill Wetlands, Forest Grove, Oregon on 29 July 2010 by Greg Gillson.
The Violet-green Swallow is the only swallow limited to western North America. In the Pacific NW they arrive in February and March and remain through September or early October. They winter from southern California and Arizona south to Middle America.
Similar to Tree Swallows, Violet-green Swallows differ by having a white face, lime-green back, and white rump divided in half by a violet strip of feathers.
These birds are very common throughout most of the Pacific NW. They occur from sea level to the tops of the mountains. They are equally at home flying over forests or towns chasing insects high in the air and uttering pleasant twittering notes.
They nest in crevices in cliffs, tree cavities, nest boxes, and holes in buildings.
In the fall, Violet-green Swallows migrate south in large flocks. Some times these flocks can number in the thousands. You may then notice them shoulder-to-shoulder on telephone wires, often near water.