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Blane Klemek column: Nighthawks are adapted to insect-catching flight

A few evenings ago, I drove my boy and the dog to the public water access of Hennepin Lake in northern Hubbard County, just a couple miles from our home. It's a favorite place of ours, as well as Duke's - our family's big Chesapeake Bay retriever. He loves jumping off the end of the dock to retrieve his black- and-white rubber dummy. I swear, I could probably throw it all day and all night long for him and he still would want me to throw it one more time.

The moon, which was about three-quarters full, was just beginning to show itself above the eastern shoreline when I heard the telltale nasal peent-call of a common nighthawk. Sure enough, a lone nighthawk was flying just above our heads, about treetop height, darting about on its long and slender wings, somewhat bat-like, capturing flying insects as it flew.

I commented to my boy that the nighthawk is a bird I just don't seem to see a lot of anymore. I recounted for him my summers in the middle of North Dakota, when I worked on wildlife research projects, and having the occasional opportunity to watch male nighthawks perform their interesting courtship flights above the rolling prairie grasslands.

Soon after we observed the lone nighthawk, we saw another. Also flying all about us was an abundance of dragonflies. A few moments later we saw even more nighthawks, until, suddenly, everywhere we looked were flying nighthawks - above the lake, above our heads, and above the near-shore forest. It was remarkable; we were virtually surrounded by hunting and foraging nighthawks.

I explained to my son that common nighthawks are perfectly adapted to their way of life. Highly maneuverable and silent on the wing, the birds' erratic flight, though seemingly ungainly looking, is incredibly effective at what they do best - capturing flying insects while they themselves stay aloft, too.

A crepuscular bird, that is, most active at both dawn and dusk, and sometimes during moonlit nights, nighthawks take flight to begin feeding during peak insect activity. During the daytime, these nearly invisible birds remain somewhat sedentary hiding in thickets on the forest floor, in woodlots, and sometimes in a comfortable roost on a stout branch of a tree.

The nighthawk's plumage of mostly brown and black feathers, along with gray and white flecks throughout, is about as cryptic of any bird I know of. Twice, again in North Dakota, I had close encounters with different nighthawks on two separate occasions. One bird was nestled in the lower branches of a tree that I stood beside. I didn't notice it until I had been standing there for a while. Another was an incubating female, which I almost stepped on before I saw her.

Possessing short legs, small feet and small bills, nighthawks (family Caprimulgidae), which are about 9½ inches long with about a 22-inch long wingspan, make up for these anatomical shortcomings with large heads and enormous mouths. It is this last feature that equips nighthawks so wonderfully well for the lifestyles they lead.

Most of their prey is flying insects such as moths and mosquitoes, so having large and wide mouths enable these acrobatic and graceful flyers to easily capture insects on the wing. Additionally, nighthawks and most other caprimulgiform birds, such as whip-poor-wills, have long bristles that grow around their bills. The bristles assist the birds in catching insects, as well as protecting their eyes from ill-timed encounters with insects.

When looking at a field guidebook of birds, nighthawks and their kin look nearly identical. But subtle differences separate the species if you look closer. While the whip-poor-will, for example, has moderately broad and rounded wings, the nighthawk flutters about on long and pointed, white-barred wings.

For sure, the nighthawk's silhouette, which is very raptor-like, nearly that of a falcon, is often mistaken for a bird-of-prey. As such, its name is really a misnomer; for the nighthawk is neither a true nocturnal bird nor is it, of course, a hawk or any other raptor whatsoever.

In the spring of the year, male nighthawks perform aerial flight displays above their breeding grounds that are accompanied by loud "booming" sounds. They accomplish the sounds in a very unusual manner. When the male nighthawk reaches the proper altitude, he enters into an abrupt and very steep dive.

As the diving nighthawk nears the earth, he bends his wings downward just seconds before coming out of his dive. Loud "booms" or "clap-like" sounds are produced as air rushes through the tips of his wings. He performs his visual and auditory aerial acrobatics over and over again. It's as fascinating an avian performance as they come.

Indeed, we are fortunate to have nighthawks as summer residents here in northern Minnesota. After the breeding and nesting season is over, they will depart on their long migrations to as far away as the Bahamas and South America.

But in the meantime, common nighthawks, undoubtedly flying in the early morning or late evening sky somewhere near you, are intriguing birds to observe as we get out and enjoy the great outdoors.

Blane Klemek is the Bemidji area assistant wildlife manager, DNR Division of Fish & Wildlife. He can be reached at bklemek@yahoo.com.

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