In spring, insects make up 99 percent of a swallow's diet. These graceful birds (which include the famed, insect-eating purple martin) are excellent flyers and much of their food—flies, beetles, winged ants, moths, grasshoppers, and dragonflies—is caught while they’re on the wing. A few species occasionally feed on the ground, chomping on ants, beetles, and other insects.
Swallows often nest in dead trees, in holes in the face of a cliff, or in banks along streams and roads. They also have a real affinity for man-made structures. Barn and cliff swallows build their characteristic muddy nests under eaves, in barns, and under bridges and culverts. To encourage this, build a nesting shelf under an eave and make a patch of mud near your garden. Tree swallows and violet-green swallows (a Northwest native) will also come to bluebird boxes (in fact, they’re probably easier to attract there than bluebirds). You can buy houses specifically for purple martins, but make sure there’s a pond or other body of water nearby, because purple martins prefer to feed on insects that live near water.
Photo: (cc) Linda Tanner/Flickr
Vireos prefer wooded areas, with most living their summers in the North and their winters in the warm South. In spring, 99 percent of their diet is caterpillars (their favorite), snails, moths, bugs, beetles, ants, and flies.
Vireos are most likely to venture into yards where clumps of dense shrubs and tangles of blackberries surround the perimeter, especially if it borders on a wooded area.
Photo: (cc) Dario Sanches/Flickr