Purple Martin Progne subis Scientific name definitions

"Almost every country tavern has a martin box on the upper part of its sign-board; and I have observed that the handsomer the box, the better does the inn generally prove to be." — John James Audubon, 1831 (1 Audubon, J. J. (1831). Ornithological Biography. Volume 1. Neill & Co. Printers, Edinburgh and London, England. Close )

Audubon's observation illustrates the long and close association between humans and the Purple Martin, a relationship that distinguishes this species from nearly all others in North America. Popular and well known to much of the public, this species in eastern North America now breeds almost exclusively in birdhouses. Its conversion to human-made martin houses from ancestral nest sites—abandoned woodpecker holes in dead snags—was nearly complete by 1900, as natural nestings were rarely recorded east of the Rocky Mountains during the 1900s. Yet in the mountain forests, deserts, and coastal areas of western North America, where the species is less common, it still nests commonly in woodpecker holes or natural cavities. Few other species show such a marked geographic difference in use of nest sites.

The popularity of the Purple Martin as a backyard bird led to a flood of scientific literature on the species, a profitable industry in birdhouse manufacturing, and national organizations and websites in which martin enthusiasts regularly communicate their observations. The Purple Martin is probably second only to the more widely distributed Barn Swallow (Hirundo rustica) as the most thoroughly studied swallow in the world.

The largest swallow breeding in North America and among the largest in the world, the Purple Martin is the northernmost species in a group of closely related species whose systematics remain unclear. The genus Progne is widely distributed in the Americas, and all of its members share similar morphology and behavior. Nine species are recognized by some authorities, but their relationships remain uncertain. The difficulty in identifying the different species in the field, and the varying taxonomic treatments, have confused the status of each in regions of Central and South America where they co-occur during at least part of the year.

Surviving on a diet consisting exclusively of flying insects, the Purple Martin is not well suited to the climatic regime of northern North America. The species has been recorded as far north as northern Yukon, northern Alaska, and central Labrador, but northerly populations are small and ephemeral. It is highly vulnerable to spells of cold and rainy weather during spring and early summer, conditions that temporarily reduce their insect food supply. Periodically, regional populations as far south as the mid-Atlantic states may be eliminated or reduced by cold weather.

As a secondary-cavity nester, the Purple Martin has also suffered from the introduction into North America of the European Starling (Sturnus vulgaris) and House Sparrow (Passer domesticus), which compete with it for nest sites throughout much of its breeding range outside of desert regions. Without human intervention and management of colony sites, European Starlings and House Sparrows can cause local extinction of the Purple Martin by appropriating their nest cavities and making them permanently unsuitable for martin use.

The Purple Martin is often considered “colonial” because multiple pairs nest in the same or adjacent birdhouses. However, colonies are not generally large enough to express either the classical costs or benefits of coloniality documented for other colonial birds, and colony size in this species seems to be determined largely by the availability of local nesting cavities.

The use of backyard birdhouses and the frequent return of individuals to the site where they nested the previous year makes the Purple Martin well suited to studies of migration, in which birds are fitted with geolocators or GPS tracking devices and then recaptured the next year for retrieval of the tags. This has yielded considerable information on the timing, routes, and behavior of birds during migration, and has allowed large numbers of birds to be tracked over time. Consequently, the migration of the Purple Martin is much better understood than that of many North American passerines.