Cliff Swallows are common in cities, farms, canyons, foothills and river valleys swooping through the air catching insects on the wing. These are colorful swallows with deep blue on their backs, wings and crown of the head; a light underside and chestnut-colored face, dark throat and pale gray nape. They can be confused with a barn swallow. Look for the white forehead, buff rump and short, squared-off tail, and two white streaks down its back to identify the cliff swallow.
Cliff swallows eat flying insects all year round. They may forage in a small group of only a couple of birds, or in large groups that may range into the hundreds. They feed on the wing following thermal air currents that bring together large numbers of insects. Cliff swallows will also help each other find food. One will follow a neighbor leaving the colony hoping to find a new source of food. A specific call can be used to alert other cliff swallows when an abundance of food is found. Their diet includes bugs, flies, bees, wasps, beetles, lacewings, mayflies, butterflies, moths, grasshoppers, crickets, dragonflies and damselflies.
Cliff swallows may be more numerous now than when the Pilgrims landed and it is because of us. Though they once only built their nests on cliffs, hence their name, now they also use man-made structures such as buildings and bridges which are more sheltered and more numerous. They are colony nesters with anywhere from 200 to 1000 nests in a colony. The most abundant colony was found in Nebraska with about 3700 nests.
Nests are made of many small mud pellets that the swallows carry in their beak from a source of water. They create a large chamber for the nest lined with grass and feathers and a narrow entrance on the side. Mom and Pop both build the nest and both will incubate, feed and raise the nestlings. A cliff swallow may lay an egg in another’s nest. And it may even carry its own egg in its bill to place it in another female swallow’s nest. They typically lay between 3 to 6 eggs; incubation takes 14 to 16 days. Young stay in the nest for 21 to 23 days after hatching, and are fed by the parents for a few more days after they leave the nest. Many young will congregate together in a group called a “crèche”. Parents can find their own young by voice even amongst this large group of juveniles.
Most of the year, they will sleep in trees, but during nesting season, they move into the nest before it is even finished. They fight and defend their nest sites. Sitting at the entrance and puffing up their feathers to look larger, they will lunge at any other swallow trying to take over the nest.
They stay in large flocks during migration, eating, preening, and bathing in large groups. Our cliff swallows will leave us after nesting season and head for South America for a warm winter. They will return to California in late winter and early spring when the weather is relatively warm and insects are abundant.
Their nesting habits can become a nuisance. Humanely keeping them away (exclusion) is the best way to handle any problems with nest sites. For more information about exclusion, please check this site: http://www.bird-x.com/swallow-control-pages-283.php.