Cliff swallows beneficiaries of manmade structures
I’ve been racking my brain in an attempt to remember if I’ve ever seen a cliff swallow (petrochelidon pyrrhonota) nest attached to something other than a manmade structure here in the Red River Valley.
I would venture to say that such a scene doesn’t exist and never has. You see the cliff swallow, like a handful of other species, has been the beneficiary of our presence to a great degree.
Without our structures, there was no place for it to be.
Prior to the settlement of the Great Plains, this was a bird restricted to the mountains of the west nesting, as its name implies, on and under cliffs. With the spread of culverts, buildings, and bridge overpasses through the heart of the continent, cliff swallows have leap-frogged across the country over the last century or so. Today it is a widespread nesting species in most of North America (except the Gulf states) and continues to colonize new areas every year.
Of the six species occurring regularly in North Dakota, I would list this one about third on the roster of publicly known swallows after purple martin and barn swallow. What makes the cliff swallow recognizable is their habit of building large colonies under bridge overpasses.
The bridge over the Sheyenne Diversion on County Road 10 had roughly 1,000 active nests attached to its underside this summer for instance. The cloud of swallows that would erupt from below at times was impressive.
I read of recent research which suggests that because of their heavy use of highway underpasses and the risk of hitting cars, the average wing length of cliff swallows is actually getting shorter making it more maneuverable. This would indicate rather rapid evolutionary pressure being put on the birds to adapt to the danger of fast automobiles.
It’s one of the mud-nest swallows. In spring it’s fascinating to watch these birds sitting by a puddle or river bank gathering mud in their beaks, all with fluttering wings held upright. Satisfied with the appropriate amount and consistency of their “adobe,” the birds fly back to selected sites to construct rather dense colonies of beady, gourd-shapes nests. The other mud-nest swallow most of us are familiar with is the barn swallow. But, it usually nests singly or in very small numbers, never in the gigantic colonies cliff swallows can produce.
As one might imagine some peculiar behavior can take place with neighbors packed so tightly together.
Nest parasitism is common where a female will lay eggs in a neighbor’s nest relieving herself of the stress of raising a chick. They will even carry an egg in their bill to deposit elsewhere. There is also a rather sophisticated vocal system to allow the adults to determine which young birds are theirs.
Distinguishing this blue-backed swallow from a barn swallow is fairly easy. It lacks the barn swallow’s forked tail, instead it is squared off. Cliff swallows also have a tawny rump patch, like someone has wrapped a pale orange bandage around its upper tail. In addition, a prominent ivory colored patch can be readily seen on its forehead giving it the appearance of a headlight or dew rag.
Like the rest of its kin, this bird is nearly 100 percent dependent upon insects for its diet, taking virtually all of it while on the wing. They are strong fliers, and frequently climb to intercept prey.
The bird is a long-distance migrant, wintering as far south as southern South America. Many of you may know of the famous mission in San Juan Capistrano, Calif., where the cliff swallows return every spring.
March 19 is the date the annual celebration takes place, although the birds show up to the area usually by late February.
In North Dakota, we can expect to see the bird appear about the middle of April and stay until the end of September. During that window of time, look for colonies of them under any structure with some overhang, often near water (the sites are abandoned now as the young have all fledged).
Several swallow species — like tree swallow and bank swallow — can readily be seen nesting in natural sites.
Not the cliff swallow. It needs us and our structures; making this a bird our pioneering ancestors likely never saw.
(Corliss is a West Fargo resident and birder and ND Game and Fish volunteer instructor. He serves as a corporate pilot for Forum Communications. firstname.lastname@example.org)