Swallows

Each autumn, almost half the bird species that breed in Washington migrate south to tropical Central and South America. This migration is one of the wonders of the natural world.

These birds, called “neotropical migrants,” spend six or more months in southern locations before returning north in spring to mate and rear young. Most vireos and warblers winter in western Mexico and northern Central America, as do tanagers, black-headed grosbeaks, orioles, swifts, and violet-green swallows. Barn and cliff swallows winter in Central and South America.

The famous swallows of Capistrano are cliff swallows, and, contrary to legend, they return to Capistrano in late February, considerably earlier than the fabled March 19.

The main reason for this seasonal migration is the lack of insects to eat during winter in the north. Avoiding cold temperatures is actually a less important reason for leaving.

Barn and cliff swallows begin their return to northern climes in late winter and early spring. Depending on weather conditions, they are first spotted in southern Oregon in late March or early April. They start appearing in British Columbia two to three weeks later.

Swallows migrate during the day, catching flying insects along the way. They will normally not move into areas unless flying insects are available for food, which occurs after a few days of relatively warm weather—60°F or more.

Swallows are usually the first to begin the southern migration in mid August to early September. They gather in large groups (sometimes as many as 2,000 birds) on telephone wires and other perches before departing.

The flowing flight of swallows can be enjoyed from dawn to dusk. Barn swallows are agile flyers that come to within inches of the ground to catch flying insects.

Cliff swallows glide, soar, and circle more than barn swallows do, and are often seen higher in the sky. When not in flight, swallows can be seen perched on utility wires, TV antennas, and on dead branches in large trees. Young swallows can be observed sticking their heads out of the nest, begging for food when a parent arrives.

Mud Sources
Barn and cliff swallows travel up to a half-mile to gather mud from the edges of ponds, puddles, and ditches. Gathering mud and constructing nests are social activities for cliff swallows; even unmated swallows may build a nest that goes unused. To find one of their mud sources, look for swallows landing on the ground—they rarely do this at times other than when nest building. The birds will remain on the ground for a minute or so and then fly off to a nest site. The collection site will be marked with numerous small holes made by the birds as they poke their beaks into the mud several times to get a good load. You may also see swallows flying with feathers or grass—materials used in the final stages of nest building.

Calls and Songs
The barn swallow’s song is a series of twitters and gurgles. They emit a soft wit wit call when feeding with other swallows, and when approaching their nests. A louder version of this call is given when there is possible danger near the nest, such as at your approach. The cliff swallow’s call is a low, soft, husky verr or churr, sounding like the squeaking of a door with rusty hinges. The song is a series of thin, strained, drawn-out rattling sounds that is shorter and simpler than the song of the barn swallow.

Many people enjoy swallows nesting on or around their homes. Colonies of cliff swallows on school grounds can provide excellent opportunities for study. The anticipation of the swallows’ arrival in the spring is exciting, watching parents feeding their young is a wonderful sight, and swallows consume thousands of flying insects that are considered pests.

It has been speculated that one reason swallows choose to nest on door stoops, light fixtures, and porch fronts is because the close proximity to humans keeps crows and other predators away. The birds will even risk cat predation and human vandalism and nest close to the ground if the location is in a place frequented by humans.

The barn swallow’s close association with humans in Europe goes back over 2,000 years. Thus, when you thwart a barn or cliff swallow’s nesting effort, you may be denying the birds their only chance at successful reproduction.

To prevent conflicts or remedy problems:

Manage swallow droppings: Conflicts with swallows occur when these birds nest close to humans, primarily because of the droppings and other debris they deposit.

When swallows first hatch, the parents eat their droppings, which keeps the nest clean and insect free. After a few days, the adults carry the droppings (which are encased in a fecal sac made from clean mucous membrane) away from the nest to prevent detection by predators. After about the twelfth day, the young back up to the edge of the nest and defecate out over the rim.

Placing newspaper or some similar material where droppings accumulate can solve the problem. As necessary, the paper and droppings can be added to a compost pile, dug into the ground (droppings make wonderful fertilizer), or placed in the garbage. Similarly, a blanket or sheet can be used to cover a car or structure, and moved when needed.

Another solution is to install a board under the nest(s) to catch the droppings and debris (Fig. 3). Because of its close proximity to the nest, the board should be cleaned as needed to prevent infestations of insects and mites that may live in the accumulated debris. Before attaching the board, observe the swallows comings and goings to prevent installing something that could interfere with the birds accessing their nest.

Create a barrier: If for some reason swallows nesting on a building or other structure cannot be tolerated, a barrier can be installed. (Again, because barn swallow populations have been on a decline for the past 20 years and cliff swallows have specific nesting requirements that are as yet unknown, preventing these species from nesting should be done only in extreme cases.)

Barriers include any physical structure placed between the swallow and the structure. A permit is not required for this method if it is done before the birds arrive, during nest building when there are no eggs or young in the nest, or after the birds have left for the winter. If swallows have eggs or young in the nest, exclusion may not be used without a permit (see “Legal Status”).

To prevent barn swallows from nesting on door jambs, window jambs, and other sites on the side of a building, cover the area with bird-netting or 1-inch mesh chicken wire. Drape the material from the outer edge of an eave down to the side of the building (Fig. 4). Remove wrinkles and folds that could trap or entangle swallows or other birds.

Bird netting and chicken wire are available from nurseries, hardware stores, and farm supply centers. Some pest-control companies sell a heavy-duty netting material with a larger mesh than common black netting used to protect fruit from birds. The netting is not as likely to create problems for songbirds, which sometimes get caught in the smaller mesh netting. To find the product, search the Internet for “bird control supplies” or look in your phone book under “Pest Control.”

Attach the barrier using staples, brass cup-hooks, adhesive backed hook-and-loop Velcro, trash-bag ties, or other fasteners. To avoid unsightly rust stains, use only rust-resistant fasteners. The barrier may also be first stapled to or wrapped once or twice around wood laths, which are then attached to the structure. This technique can also be modified to keep swallows from entering a breezeway, or similar sites, to nest.

Another technique is to hang a curtain of bird netting or chicken wire from the eave (Fig. 4). The curtain should be 3 to 4 inches from the wall and extend down from the eave 18 inches or more. A well done application under the eaves is nearly invisible from 50 feet because it is in a shaded area and gets obscured by the shadows.

A solution for small areas is to install aluminum foil, aluminum flashing, or heavy plastic over the spot where swallow nests are unwanted. The smooth surface will prevent swallows from adhering mud to the wall. Painting the area with a glossy latex paint may also be effective. It may be possible to offer barn swallows an optional nesting site by constructing a nest platform (Fig. 5).

Note: Hawk, owl, and snake models, noisemakers, revolving lights, red-and-silver flash tape, and hanging pie tins are unlikely to deter swallows.

Nest removal: At the first sign of nest building, remove the nest. Note: All swallows are protected under the law. You cannot disturb them once they lay their eggs in the nest (see “Legal Status”).

Usually nests can be washed down with a water hose or knocked down with a pole. Because swallows are persistent at rebuilding nests, you will need to continually remove the nest mud for several days until the birds stop. Swallows are strongly attracted to old nests or to the remnants of deteriorated nests, so all traces of mud should be removed.

For information on what to do if young swallows fall from a nest, see the handout, “Baby Birds out of the Nest.”