Learn about the barn swallow bird and what makes them unique.
A barn swallows perched on a branch looks for a meal.
The barn swallow (Hirundo rustica) is one of the most widely recognized species of bird in the world. Found on nearly every continent, it is also one of the most reliably regular migratory birds. Some folks swear you can set your calendar by their annual flights. Myself having had to replant a frost-damaged garden that was set out pre-swallow return, they are as reliable an indicator of spring as the robin.
Swallows migrate thousands of miles from their winter grounds in South and Central America to their breeding and nesting grounds in North America. Males are generally the first to return, in order to scout out nesting territory and nest sites, and they will retreat south in the event of a late freeze.
By late March to mid-April, barn swallows will have returned to most parts of the southern and central United States. They spend summers feasting on pest insects like flies and mosquitoes. By August — having raised one or two clutches of eggs — the birds head back to their winter grounds to molt, rest, and do it all over again in the spring.
Swallows can lay a clutch of up to seven eggs, but usually average only three or four. The incubation period is around 14 days, and both male and female will share incubation duties. The chicks grow fast and will fledge in about three weeks. Many pairs will go ahead and raise a second clutch during the breeding season. The adolescents from the first clutch will hang around with their parents for the rest of the season.
Interestingly enough, it isn’t the cold temperatures of North American winters that drive the birds south, it’s the lack of insects on which to feed. Almost exclusively insectivores, barn swallows are dynamic aerial feeders. They eat almost constantly and nearly exclusively on the wing, swooping and diving over open fields in search of the tasty insects, which comprise 99 percent of their diet.
While there are several subspecies globally, all barn swallows share the distinct cobalt blue back and rufous throat, chin and forehead, as well as the deeply forked tail unique to swallow species. Males and females are quite similar, but the females’ bellies are slightly paler, and the tail is not quite so forked. Adults weigh between 1/2 and 3/4 of an ounce. They have a distinctive flight pattern, rolling and darting through the air, soaring up, and then diving down again with brilliant ease. They even drink and bathe on the wing, sweeping low enough to grab a mouthful of water, or a quick dunk to clean up.
Their aerobatic ability is enhanced by their forked tail, which automatically deflects air currents, allowing them sharper angles of flight, higher aerodynamic lift, and greater maneuverability. Engineers have studied the swallow in depth in hopes of improving airplane design and function.
Those tail streamers do more than just give the birds their incredible aerobatic skills, though. Males with long, robust tail streamers have better success with the ladies, too. In one study, males that were not able to attract a mate had significantly shorter tail streamers than their luckier counterparts. Longer tail streamers in males likely signal enhanced vitality and superior genetics, which helps explain their role in the mating selection process.
Barn swallows have a long history with humans. Literary references to swallows nesting in barns can be found in ancient Greek poetry. Their nests were originally built in cliffs and cave faces, but with the advent of agriculture — and the barns and livestock that attract a smorgasbord of insects — barn swallows moved their nests and hunting grounds closer to where mealtime was a sure thing.
The birds were considered to be so beneficial that several superstitions arose about all the horrible things that could happen if a person were careless enough to harm one or disturb a nest. They were also popular among nautical men as a symbol of safe return from a long journey. And in the craft of heraldry, the swallow being a migratory bird represents younger sons who have no land of their own to rest on.
Barn swallow nests represent a prodigious effort by the tiny birds. Each nest is made up of hundreds of tiny mouthfuls of mud, blended together with grass, feathers or hair to give it stability. When creating a new nest, which can take up to two weeks, both males and females will help with construction, travelling up to a half mile searching for mud. Naturally, whenever possible, the birds like to return to last year’s nest. Mated pairs will often use the same nest year after year.
When creating their cup-shaped nests, the birds prefer to use rough wood for a solid base. They will often begin building over an exposed nail, electrical box or other protrusion to give the nest a firm foundation.
They generally nest in colonies, typically in five to seven pairs of birds. Some large, well-established colonies have been documented at housing an astonishing 45 nests. Single nests are uncommon, but not unheard of.
Swallows are protected by the Migratory Bird Act. It is illegal to remove a nest containing an adult, chick or egg. Even if it’s a half-built nest, the law protects it. The only time you do not need a permit to remove a nest is in the winter when the nests have been abandoned for the season, or very early in the nest-making process before the nest takes form. But be warned, once they find a preferred site, they loathe giving it up, and they may try again and again.
Though they are not threatened globally, and populations are considered high, the decline in farmland in recent years has had a negative impact on their numbers. One can only imagine the birds’ confusion upon returning to last year’s wonderful old barn nesting site, only to find the barn gone, the meadow buried under asphalt, and an apartment complex in its place. The birds are adaptable, though, and will readily take to new sites if available.
There are several things you can do to help attract barn swallows to your property. The first and most important thing is to have a wide open area, preferably a pasture or meadow, where they can catch insects while in flight. Equally important is a water source, which is necessary for attracting any sort of wildlife, but is also vital as a source of mud necessary to create the swallow’s nest. If there are no ponds nearby, trays or plates of mud can be set out to help attract the birds.
Swallows love open-faced barns or loafing sheds, especially ones with overhanging sides. Many modern barns with smooth wood or sheet metal do not have ideal nesting surfaces for barn swallows. Rough wood is preferable for giving the nest something to adhere to. You can also attach boards to smooth surfaces to encourage nesting. They prefer to build their nests up high, close to the ceiling of the barn, so keep that in mind when putting nesting boards up.
In addition, you can purchase artificial nests, which under the right conditions, barn swallow colonies seem to prefer. Creating artificial nest colonies can also help to relocate swallows if they have chosen a less-than-desirable site — say, right over the front door or in a light fixture.
If you do get a colony established, watch for encroaching house sparrows. Sparrows have been known to reduce the hatching success of swallows by as much as 45 percent by taking over the nest and kicking the baby swallows out.
In the unlikely event that you should want to deter barn swallows from nesting on your property, there are several non-lethal methods you can use. One of the simplest is to attach chicken wire or hail screen from the edge of the eve they have built under to the building at an angle, thereby limiting their access. Tin flashing can also be installed on the undesirable site, keeping them from having a surface to attach their nests to. Also, a couple of coats of paint can make the surface smooth enough to keep the nests from attaching.
If you want the birds, but can’t handle the droppings, install a shelf under the nests. Newspaper or a piece of thin paneling or plastic can be laid over the shelf and removed or cleaned after nesting season.
Barn swallows are one of the most beneficial species we are privileged to interact with. Watching them gracefully glide through the air with their aerodynamic expertise provides hours of enjoyment, and combined with their insect eating capabilities, having them around is pure joy.
Looking for more on barn swallows? Check out Shirley “Rodeo” Landis VanScoyk’s article on signs of spring, “The Barn Swallows Return.”
Callene Rapp enjoys watching barn swallows around her Kansas homestead, which she manages with her husband, Eric.
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