Because several members of the swallow family spend the summer months in our area. These birds are closely related, as their body shapes – morphology – and their food habits suggest. They are unique species, nonetheless, each with its own niche.
Swallows are small birds with long, swept-back wings. These make them efficient predators on flying insects, which is lucky for us. Summer and flying insects are synonymous in our part of the world – and in many others.
Perhaps for that reason, the Red River Valley is rich in swallow species. Four are common here, and two more are regular and sometimes locally abundant. That is a total of six swallow species that can be expected in the buggy months, like this one, July 2020.
The word swallow often conjures up the fork-tailed member of the clan, the barn swallow, and the barn swallow is indeed a worthy representative. While the barn swallow may be the most familiar swallow, it is not the most abundant swallow in our area. That distinction probably belongs to the cliff swallow.
Yes, I am equivocating here. In some localities, one or another species of swallow may be more common, but overall, the cliff swallow probably outranks other swallow species in abundance in our area.
As is always the case with wildlife species, the critical element is available habitat. For this reason, tree swallows are more likely to be encountered in areas with wooded lakes. They are especially abundant in the Devils Lake area, where drowned forests and burgeoning insect populations provide easy living. Likewise, bank swallows are likely the most numerous along prairie streams, especially those with “cut banks.” The swallows tunnel their way into the soft soil layers and make their nests there.
Cleverness in building technique is characteristic of the swallow clan. Barn swallows build cup-shaped nests under some sort of sheltering structure, such as the eaves of rural buildings, or sometimes inside rural buildings. Purple martins, the largest species of the swallow clan, readily move into structures provided by humankind.
Cliff swallows build bottle-shaped nests under bridges or plastered against the sides of buildings. It is not hard to imagine how mankind’s building techniques have favored cliff swallows, resulting in what is almost certainly a far larger population of this bird species than existed in the days before European settlement. At that time, cliff swallows were likely restricted to mountainous areas that offered – you guessed it – cliffs on which to anchor nests.
But the cliff swallow is a pioneering species, in some ways like we humans ourselves. Cliff swallow scouts seek out appropriate nesting sites. These sites would have been limited to exposed rock faces, but cliff swallows readily adapted to man-made structures, and they are now common under bridges, on the sides of farm buildings and even in the relatively limited space provided by a rural road culvert. This adaptability, coupled with a pioneering spirit (perhaps we should call it an “evolutionary imperative”), has helped the cliff swallow to expand across the Great Plains.
Other swallow species have been successful as well, but the most successful of all have been those most able to respond to changes in habitat that expanded human populations have created. Here again, the evidence favors the cliff swallow.
Still, adaptability and abundance have not made the cliff swallow as familiar as the barn swallow, which is the model against which other swallows are identified. The cliff swallow is most like the barn swallows; the most obvious field mark separating the two is the tail, deeply forked among barn swallows and nearly square among cliff swallows.
Purple martins are the largest of the swallow clan, and they can usually be identified by their size and their close connection with man-made nesting structures. Tree swallows might be confused with purple martins because they are two-toned, as martins are. Like martins, they are also iridescent. The least common of local swallow species is also the loner among the group. Rough-winged swallows are ordinarily solitary nesters, and they are plain birds, lacking the plumage details that help to identify other members of the swallow clan.
So, we have six species of swallows:
Purple martins, largest of them, are iridescent blue or purple on the back and white below. Usually city birds, purple martins often take to “high rises,” occupying multi- roomed bird houses provided for them.
Tree swallow, the lake dwellers of the group.
Barn swallows and cliff swallows, superficially very much alike, except for the tail feathers.
Bank swallows, drabber and more specialized as to habitat.
And rough-winged swallows, the loners of the group.
Jacobs is a retired publisher and editor of the Herald. Reach him at mjacobs@polarcomm.com.
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Always in Season/ Mike Jacobs: Insects feed swallows, the birds of summer - Grand Forks Herald
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