I always enjoy checking out the Purple Martin houses behind a home on Sauvie Island. These large swallows are one of the more popular yard birds in the eastern U.S. , but the species is much less common in the West. This site on Sauvie Island is one of the few places in the Portland area to find them.
Here a female is putting nesting material into a martin house. The “natural” nesting habitat for Purple Martins is a cavity, usually an old woodpecker hole. But for the past two centuries, most of the population has chosen to nest in man-made structures.