Barn Swallow (Hirundo rustica)
Article by Ed Coleman, Virginia Master Naturalist, Southwestern Piedmont Chapter, August 24, 2023
Mother Nature's proclamation that spring has arrived can be received differently by each of us. For some, it's the chorus song of male spring peepers, the emergence of mason bees from their sealed chambers, or perhaps the spawning of striped bass in the Roanoke river. For me, the announcement that the cycle of life is ready to begin anew coincides with the return of barn swallows to our farm in Floyd County. In early May, as the trees begin to leaf out in the Blue Ridge mountains, somewhere between 50 and 70 barn swallows arrive to take up residence in the old block barn, just as they have done every year since its construction more than 60 years ago. This may be the first visit to our farm for some of our migrating guests, while others have been here before. For their summer stay, the recent arrivals have chosen our "airbnb" above other potential sites because of its amenities - a sheltered site for nesting, nearby meadows with lots of insects, and a farm pond for drinking, bathing, and scooping up mud. For the next three months the farm will be alive from dusk to dawn with a constant chatter as the barn swallows scour the open meadows in search of food, build nests, and raise young.
Photo by Ed Coleman - Circa 1960 block barn, summer home of the barn swallows
Barns swallows, like other swallows, martins and swifts, are aerial insectivores, meaning their diet is composed mainly of flying insects such as flies, dragonflies, butterflies, moths, beetles, bees, and wasps which they catch in flight. Look for them feeding on insects above meadows, athletic fields, and water, sometimes flying just a few inches above the surface. With quick turns, dives, and speeds up to 45 miles per hour, few insects are safe from these incredible, little acrobats. They even drink and bathe on the fly. Leave your parked car windows down and they will fly straight through. On our farm, those pesky flies that swarm the angus herd provide a constant source of food, but for our summer guests, the bounty of the season comes during the midsummer hay harvest. As the tractor slowly pulls the hay mower through the meadows, the barn swallows follow closely feasting upon the exposed insects previously hidden among the tall grasses. The second course is served two days later when the hay rake whorls the recently cut grass into windrows exposing insects that did not fall victim to prey earlier in the week. Since our hay harvest season runs for several weeks, summer on the farm is a time of plenty, if you are a barn swallow that is. Ornithologist Arthur C. Bent described the symbiotic relationship between barn swallows and farmers best when in the early 1900s he wrote "No bird in North America is better known as a welcome companion and a useful friend to the farmer, as it courses about the barnyard in pursuit of the troublesome insects that annoy both man and beast."
A barn swallow is about the size of a sparrow, with a wingspan around 12 to 13 inches. Its back and tail are cobalt-blue, belly is tawny, and throat and forehead are chestnut. Males and females are similar in appearance, although females tend to be less vibrantly colored and have shorter tails. The long forked tail and pointed wings of barn swallows make them easily recognizable from other swallows. According to legend, the barn swallow got its forked tail because it stole fire from the gods to bring to the people. In retaliation for this thievery, an angry deity hurled a firebrand at the swallow, singeing away its middle tail feathers. In real life however, it was their long tail feathers that got this species into trouble. Feathers of barn swallows were much sought after for the millinery trade during the late 1800's. Outraged by the killing of barn swallows simply to adorn lady's hats prompted George Grinnell's 1886 editorial in Forest and Stream. His article ultimately led to the founding of the first Audubon Society and the passage of the Migratory Bird Treaty Act. The Migratory Bird Treaty Act of 1918 outlawed the killing of migratory birds without the appropriate license and made it illegal to possess feathers, nests, or eggs.
Photo by Ed Coleman - Adult barn swallows (Hirundo rustica erythrogaster)
Before the existence
of human structures in North America, barn swallows nested on rocky surfaces that were protected from
weather such as caves or cliffs. Since the establishment of permanent
settlements in the new world, populations of barn swallows have grown in tandem
with clearing of forest land for farmsteads.
Farm buildings located in close proximity to open meadows provide ideal
habitat for nesting and forging. As
farmsteads continue to give way to suburban expansion, barn swallows appear to
be successfully transitioning to highway overpasses. The underside of these modern-day concrete
caves provide protected shelter for nesting sites and the highway medians
surrounding them apparently provide
enough open area for forging on insects. Whether built in a barn or under a
highway overpass, semicircular half-cupped mud nests are generally attached to
a vertical wall. Nests measure somewhere
between 3 to 5 inches across at the rim and 2 to 5 inches deep. A pair of barn swallows can make over 1,000 trips to build a
new nest as they scoop up mud in their bills from nearby puddles,
stream banks, or ponds to mix with grass. Nests are then lined with grass and feathers.
Due to the effort involved in building a new nest, barn swallows frequently
reuse existing nests after cleaning them out and adding new mud to the rim.
Photo by Ed Coleman - Barn swallow nest
The female barn swallow lays three to seven eggs. Both parents incubate the eggs, which hatch in about 14 days. Barn swallow chicks are naked and helpless when they hatch and remain in the nest for about 20 days before fledging. Both parents feed and protect the chicks through the first week after fledging. Barn swallow pairs often have two broods a year, sometimes in the same nest. On the farm, I observe the first fledglings around the first or second week of July and see the last ones in early August just before they start migrating south.
Photo by Ed Coleman - Barn swallow fledglings (Hirundo rustica erythrogaster)
It is now late August
and time to say good-bye to our summer residents. As the barn swallows begin to
leave the farm for their long journey home, I get that same pit in my stomach
that every parent gets when they see their children drive away. Will they make it to their destination
safely?, I worry. Perhaps there is a
farmer in Chile or Argentina eagerly anticipating their return. As they head south, barn swallows and their
young join others to form enormous flocks for the migration which will take several months. It will be spring when they arrive in the
southern hemisphere. As summer turns to
fall, the cooler air will trigger their feathers to molt.
Shortly thereafter, the northern flight of the barn swallows will begin anew.
Sources:
American Bird
Conservancy
https://abcbirds.org/bird/barn-swallow-3/
Tennessee Wildlife
Agency
https://www.tn.gov/twra/wildlife/birds/barn-swallow.html
University of
Michigan Museum of Zoology
https://animaldiversity.org/accounts/Hirundo_rustica/
The Cornell Lab All
About Birds
https://www.allaboutbirds.org/guide/Barn_Swallow/id
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