On Aug. 9, the purple martins were swooping and darting over the Unity baseball fields and popping in and out of their pole-top condominium just as they had since May. On Aug. 11, all was eerily quiet. They had vanished into thin air.
The southward migration of the martins, it turns out, begins in mid-August. They arrive in Maine during April or May, usually preceded by a few “scouts” who are older birds that know the landscape and come ahead of the rest to check on last summer’s digs, which they strongly prefer. If everything is copasetic the later-arriving families move in and set to work feathering nests and laying four or five white eggs. Copasetic — or to use the less casual technical phrase “site fidelity” — means the place is still clean, solid, handy to water and unobstructed by trees or other skyscrapers so they can swoop and swerve in and out of the roost. It helps if there’s no immediate threat from starlings or house sparrows, who will knock eggs out of the nest to crack them open and will actually kill adult martins.
Purple martins are the largest dominion of swallows that frequent our sky. Their relatives are barn swallows (with rusty orange bellies), cliff swallows and tree swallows. They’re exceptionally gregarious, and how many martins will fit in a birdhouse — or on the head of a pin — depends mainly on the size of your imagination of a residence. Audubon says they’ll dwell in anything from a one-room efficiency to a 200-unit complex. They travel together in even larger flocks to their winter homes as far as deepmost South America, though it is apparently not known exactly which flocks fly how far south.
People have been cheered by purple martins for literally time immemorial. The early European settlers noticed that the Indians put gourds on tall poles around their gardens for the martins to nest in, and imitated the tactic by constructing birdhouses because the martins are bug-eaters, clearing the air of all kinds of flying demons, from midges to flies to wasps.
They do this with Blue Angel deftness. They turn, twist, dive and climb in extraordinary improvised dances on the very air. They buzz down like fighter planes if you get too close to the digs. They chatter together with tremendous energy on wing and roost, and when the sunlight strikes their dark-blue feathers, their heads burn with a blue iridescence. Their point-tipped wings in flight look like the gear of aerial spirits, and on a perch fold into upthrust shoulders like ancient depictions of angels. Which came first, the angels or the martins, I’m not sure.
They are a couple of weeks gone now. Presumably most of them have weathered the hurricane that rolled up the East Coast this weekend, and I imagine their southern principalities are filling with the same perennial here-and-goneness.
Dana Wilde’s collection of Amateur Naturalist and other writings, “The Other End of the Driveway,” is available in paperback and electronic book from www.booklocker.com and from online and local book sellers.