The Purple Martin is the largest North American swallow (Family Hirundinidae), with a wingspan of 18 inches, length of 8 inches, and weight of 2 ounces. It is about the size and appearance of a starling in flight and can be confused with it. (In both species, the purple is due to iridescence of feather structure, not pigment.)
The male Purple Martin is bluish black and unmistakable. The female is gray on the head and neck and grayish brown-streaked underneath. The female of western populations is more whitish on the head and neck and paler underneath. All Purple Martins have a forked tail. The song of the male is a melodious gurgling while the female has a more whistling song. Both sexes make a geerrt call when alarmed (1).
Purple Martins prefer open land, including farms and residential areas. They nest over most of the U.S. east of the Rockies and west of the Great Basin on the Pacific coast. Although they nest in trees with lots of woodpecker holes in the wild, humans have encouraged them for their very effective eating of flying insects for hundreds of years, going back to Native Americans who hung out hollow gourds to encourage them to nest near their gardens. European Americans followed suit with multi-compartmental bird houses because of their colonial nesting preference. Here they make a grassy nest and incubate four or five white eggs. They winter in the tropics, for their diet cannot be sustained in the northern winter (2). John James Audubon, nineteenth century American naturalist and artist, wrote that Martin houses could be found at many country taverns, and he chose accommodations for the night by how well the proprietors’ provided for the birds.
The nest boxes do take care, however. I remember my neighbor going through the laborious process of taking down the long pipe with the cumbersome housing complex in the fall, cleaning it, and putting it back up in the spring, but not so early as to give the sparrows or starlings a chance to get started. Older Purple Martins return to the familiar nesting places earlier than younger birds. The Missouri Department of Conservation recommends not putting the houses up until four to six weeks after the first birds have returned to avoid unwanted tenants. Western birds still tend to prefer woodpecker holes.
Purple Martins are beautiful and graceful birds as they swoop down on insects and circle in the dozens around their communal home in the evening. Furthermore, they even drink by skimming water with their beaks. Martins gather in large flocks to migrate in the late summer (https://www.allaboutbirds.org/guide/Purple_Martin/overview). To Swallow admirers, another familiar sight may be that of Tree Swallows that line up by the thousands on electric and phone lines as they migrate south in late summer. Tree Swallows are smaller than Martins and have a square tail. For Swallow nest construction effort, I always admired the sturdy, mud houses under the protective eaves of a barn that Barn Swallows made. Barn Swallows are smaller than Martins and have a long, forked tail. All of these long, pointed-winged benefactors of humans are welcome on the farm or in the city.
- National Audubon Society: The Sibley Guide to Birds, Alfred A. Knopf, Inc., New York, 2000 by David Allen Sibley
- National Audubon Society: Field Guide to North American Birds, Alfred A. Knopf, Inc., New York, 1998 by John Bull and John Farrand, Jr.
