A tree swallow (Tachycineta bicolor), known as a tuxedoed aerialist because of its iridescent blue-green back and brilliant white breast, can be found in the fields of the central Piedmont. Photo by MadRapp/GreeneJournal courtesy of Melissa Wine.
Our farm attracts several species of swallows – barn swallows, purple martins and tree swallows. They are most active in the early morning and at dusk – or when my husband is mowing the lawn and flushing out the insects.
The most dramatic of the three species is the Tree Swallow (Tachycineta bicolor), both for its iridescent blue-green back and brilliant white breast and for the size of the flocks that arrive in midsummer to assemble for the fall migration.
This time of year, I can easily see 50 to 75 swallows sitting on the power lines that run across our field and the driveway of our neighbor’s farm.
These are the early migrants. The most I have counted this year is 250 – and when I was making my records on eBird, I “asked” for an explanation for this high number.
Last year I counted a maximum of 500 swallows. That was later in the summer and closer to the time when most swallows began their migration.
This time of year, the early migrants can often be found perched on power lines in the early morning and at dusk. MadRapp/GreeneJournal photo by ORMN member Charlene Uhl.
Tree swallows are found on coastal beaches, freshwater ponds and lakes, and in agricultural fields.
They are voracious insectivores and can be seen demonstrating their flying skills when a storm approaches and the wind drives the insects along the ground.
They eat all kinds of flying insects as well as spiders and mollusks. The size of their prey ranges from smaller than a grain of sand to 2 inches long. They hunt their prey with acrobatic twists and turns, which is why they were nicknamed Aerial acrobat in tuxedo.
Virginia is the southernmost breeding area for tree swallows. Large groups migrate deep into northern Canada to breed. Tree swallows are cavity nesters, as we discovered when they took over one of our bluebird houses last year. And their nest was beautifully lined with white feathers.
They are known to travel long distances to find feathers to line their nests.
They have also been observed playing with and chasing fallen feathers before taking them into the nest box.
The nest robbers are the same animals that often raid cave nests: snakes, raccoons, bears, wild cats and the like.
Although they are not considered endangered, their population has been slowly declining over the past 50 years due to the disappearance of natural caves. They have also been sensitive to climate change.
The average life expectancy of a tree swallow is 2.7 years. The survival rate in the first year is low – 79 percent do not survive the first year.
The oldest recorded tree swallow was twelve years old.
If the increasing numbers of Tree Swallows on our farm are any indication, their migration south is beginning, so keep an eye out for these adorable aerial acrobats!
