Blane Klemek: Swallows that make their summer homes in Minnesota

As soon as springtime warms enough to where insects are fairly abundant, several species of swallows begin showing up throughout Minnesota. In all, six of the nine North American swallows migrate to Minnesota to breed and nest. All of them share similar physical characteristics with one another, but each is quite unique in their own right.
Just recently in fact, I stopped at a public water access of the Clearwater River a dozen or so miles north of Gully, Minn., to let my dog out of the vehicle for a stretch and a short break. The two of us were on our way further north to the Karlstad area.
After I began to walk with the dog toward the river I suddenly became aware of a loud and noisy swarm of cliff swallows streaming endlessly from underneath the highway bridge that spanned the river. Mesmerizing as the spectacle was from my distant vantage, I couldn’t help myself in approaching closer for an even better and more intimate view.
The cliff swallows’ incessant vocal chatter, coupled with the rushing sound of the river as its swift current flowed against the bridge’s support columns, along with the visual image of tens of hundreds of flying swallows streaming upstream and downstream, made for a confusing cacophony of both sight and sound. It was delightful.
Equally as enthralling was the sight underneath the bridge’s support beams of literally hundreds of gourde-shaped nests made completely out of mud securely glued to metal structures in row upon boundless row. And about those nests: I’ve often mused that most human hands would have great difficulty trying to replicate the artistry that the cliff swallow nest represents - the perfectly shaped gourde, the neat round entrance hole at the end of each of the gourdes’ short necks, and the salivary adhesive substance produced from the swallow itself that holds the mud together as individual sticky mud pellets.
The other species of swallows that make their summer homes in Minnesota include the omnipresent tree swallow, which is a species that frequently takes residence in vacant bluebird houses, as well as the abundantly happy-go-lucky barn swallow, and the not-as-common bank swallow and northern rough-winged swallow, and last but not least, the beautiful purple martin - the main subject of this week’s column.
Probably topping the popularity list of Minnesota’s “swallow six” and the largest of the swallow clan (in addition to the only species of swallow not to have “swallow” as part of their name) is very likely the purple martin.
Indeed, purple martins are those condo-loving swallows that people everywhere try to lure to their backyards by erecting complex miniature houses that often really do look like houses; to assemblages of hanging gourdes clanking and swaying in the breeze. Strangely, the purple martin is a species of swallow that has come to rely almost exclusively, interestingly enough, on human-made bird houses and other structure for nesting.
Like several other swallow relatives, purple martins are cavity nesters - that is, they evolved to nest inside of holes in trees - holes commonly excavated by woodpeckers. But perhaps due in part by loss of their preferred nesting habitat (larger trees with suitable tree cavities), these colonial nesting birds somehow adapted to nesting in bird houses.  
Oddly, purple martins east of the Rocky Mountains rely almost entirely on “human provided housing,” whereas those birds nesting west of the Rockies typically nest in their ancestral ways inside of tree cavities.
Even so, the population of this widespread swallow has declined dramatically over the past 40 to 50 years. It is estimated that purple martin numbers have decreased by as much as 80 percent. Since the mid-1960s until the late 2000s according to data from the North American Breeding Bird Survey, the purple martin population has declined by as much as four percent each year.
And the primary reasons cited for the decline in purple martin abundance?  Likely culprits are two non-native species of birds - the house sparrow and European starling. Another possibility that is believed to be contributing to purple martin population losses, are that fewer houses are available for the species to nest in.
There was a time across the American countryside when purple martin houses could be found adorning the front yards of farms everywhere throughout purple martin range. It’s surmised that with the loss of family farms, so too has the thousands of purple martin houses that once were a mainstay of our agrarian past.         
Still, despite the continuance of purple martin population declines, the fondness for this wonderful creature has never diminished. In recent times, public awareness has thankfully increased, purple martin societies have been organized, and efforts are underway everywhere to bring back purple martins to historic numbers.
While all species of swallows are birds of beauty and grace, the purple martin cannot help but capture our utmost admiration. A social, graceful, and beautiful bird, perhaps with a our helping hands and our front and backyards we will begin to see and hear once again more purple martins as we get out and enjoy the great outdoors.
Blane Klemek is a Minnesota DNR wildlife manager. He can be reached at bklemek@ yahoo.com.