A friend in Alaska put out nest boxes for them at his house, partly just to enjoy their presence and partly for their prowess in catching mosquitoes. Each year when the young Tree Swallows fledged and the families departed for milder climes, he would notice a big uptick in the number of mosquitoes around his house.
Barn Swallows on the Diamond A (Photo by Narca)
Swallows belong to a cosmopolitan family, gracing every continent except Antarctica. Many sport brilliant colors, and some have long tail streamers to aid their aerial adroitness. Journey up the rivers of the Amazon Basin and you'll find swallows. Land at an airport in Australia, and you are likely to be greeted by their Welcome Swallow. Isn't that a great name?
Swallow migration has always fascinated me. As strong fliers, they often migrate by day, feeding on aerial insects as they go. Once, about October, I was guiding a World Wildlife Fund tour in the cerrado of central Brazil, a region dominated by giant termite mounds. The rains had begun about two weeks earlier. On our first day, we saw only one or two swallows, and I was puzzled by their absence. Usually in the Brazilian spring, hundreds of swallows and martins (their larger cousins) are swooping over the shrubby grasslands of the cerrado. That night it rained again, and by morning winged termites were emerging in the millions. And overhead the morning sky was dark with thousands of Cliff Swallows, which had arrived overnight, timing their appearance to match perfectly the emergence of this bounty of food.
Here in the States, seven species of swallows, plus the Purple Martin, breed regularly. The most local of those is the Cave Swallow. Here's a tip for finding it in West Texas: take the frontage roads off I-10, and check the highway underpasses for the swallows' mud nests. Sometimes the nests of Cave Swallows will be mixed in with those of Cliff Swallows, and sometimes you'll find a small, pure colony of Caves.
Barn Swallow detail from Self Portrait as Garden