By June, dark purple avian returnees from South American regions are back in Michigan, mating, nesting, bringing off their young, and often residing in human-provided “condos.”

June is the prime time of the purple martin (Progne subi). These purple-hued birds of summer are swift and agile—they swoop, soar, dive and twist in seemingly effortless acrobatics that would make an Olympic gymnast envious. Once June’s ample insect hatches take flight, these feathered acrobats give a flying circus performance by catching and feeding on pesky summer insects.

Purple martins have a slender body, long wings, and a wide beak. The tail is forked, but not deeply as in some other swallows. Males, with their dark plumage, often appear to be black; but in bright sun their shiny blue-black coloration is clearly visible. Females are lighter in color, showing a pale gray throat and belly. By the time they leave the nest, young martins of both sexes resemble adult females. Young males do not darken fully until their second breeding season.

Martins prey on many kinds of flying insects—‘skeeters,’ midges, moths, dragonflies, June bugs, wasps, bees, and other insects—that flit and often annoy humans. When it comes to catching and consuming bugs on the wing, a single purple martin can consume an astonishing amount of insect fodder daily.

When martins need water, they get it the same way as their insect meals—in flight. They fly close to the water, their lower bill skimming in to scoop up the water.

Native-born martins are quick to leave our temperate zone once they have mated, nested, fledged, trained and prepared their young for the return to South America—where there’s no off-season on flying bugs. This makes them more “snow birds” than the human ones that head to Florida, Texas or Arizona once hints of frosty nights arrive.

Martins have been returning back to Michigan each year for eons. The birds were first attracted to Native American villages, where they were welcomed with hollowed gourds to nest in (martins are not “feeder” birds). Native people noticed the martins’ diet of flying insects and ample consumption of mosquitoes and other annoying insects, which made them welcome to their hosts.

Martins are colonizing birds, usually coming back to the same places each year to reclaim colony territories. This largest of the North American swallows is most often found using backyard birdhouses. In eastern North America, for more than 100 years, they’ve resided almost exclusively in nest boxes.

By the mid-20th century, following logging, farming and other human land use changes, habitat for martins all but disappeared, making them near-endangered. Realizing that purple martins were totally dependent on man-made quarters, it became apparent some help from people would be needed. Today, artificial man-made “housing” in the form of martin houses—often multi-nesting condos—provides the majority of nesting sites for this summer returnee.

Their return north begins in late April or May when one or two “scouts” arrive at the beginning of each season. Within two to three weeks after scouts are spotted, the rest of the colony starts to arrive. Immature birds take longer. Once here, they move quickly to take up residence in human-provided housing. Mating and nesting begin quickly, since the summer season in this region is relatively short, and fall migration begins as soon as the birds are fledged and ready for migratory flight, long before other birds begin to head south.

People who use martin houses need to scare off or discourage other birds from using the nest boxes until the martins arrive. Opportunistic starlings, English sparrows and other birds are quick to reside in the man-made housing. But once martins move in, they will fiercely defend the nest.

Because martins are a colony species, establishing new martin sites means being near to habitat that supports them–this means water. Not every site is going to attract this bird, even with martin birdhouses.

Once mating occurs, egg incubation takes 14-16 days. Baby martins will fledge about 28 days from hatching. When that happens, you will be lucky to be on hand. All martins in the area come to help encourage the “youngsters” to take their first flight. After martins fledge, they gather together in nearby roost areas.

Martins begin southward migration within three weeks of the young being fledged. Adult males are the first to leave, followed shortly by adult females and immature birds. Their migration normally begins in July and most birds are gone by the end of August, on the final leg of their migration back to Brazil.

But while they’re here, they will again provide one of nature’s best air shows–free for the watching.