Nature Notes: The Passage of the Nighthawks

Nature Notes By Jim Gilbert

Anytime after mid-August and into early September, naturalists and birders are aware that it’s nighthawk migrating time.  In afternoons and early evenings, flocks of these blue jay-size, dark-colored birds with long pointed, white patched wings can be seen gliding, diving, and circling, feeding on insects in the air and definitely heading south.  Having been summer residents throughout Minnesota, the common nighthawks are on their way to winter in South America.  This year the first migrating nighthawks were seen over our area west of Minneapolis on Aug. 13, about 7:45 p.m.

During fall migration, sometimes as many as a thousand common nighthawks are seen in a flock.  Large migration flights have been recorded in Duluth where in late afternoons a thousand birds per hour could be observed between Aug. 18 and 25.

The common nighthawk is a wide-ranging aerial forager that is found regularly over many habitat types including prairie, cropland, woodlands, wetlands, and residential and business districts of towns and cities.  They have a tiny bill but big, gaping mouth.  The birds sweep up in their large mouths all types of flying insects from large moths and beetles to the tiniest of flies and mosquitoes.  The remains of 34 May beetles were found in one nighthawk stomach.

The magical date we look into the sky and spot the first loose flock of nighthawks wheeling by for me marks the beginning of autumn.  It’s true that in our social community, Labor Day, 11 days away, marks the official end of summer.  It’s also true that the autumnal equinox in the third week of September marks the end of celestial summer.

But, August slowly cools toward September and autumn.  The time after the first common nighthawks move through is one of the best times to be out of doors, enjoying the cool fresh weather fronts as they pass by, giving us crystalline late-summer weather.  The lakes are still warm enough for refreshing swims, the insect chorus is great, and there is plenty of food for wild creatures.

What’s happening outdoors now?
Both great and common ragweeds are shedding big quantities of pollen; we have arrived at the peak of the ragweed pollen season.  Among the many flowers attracting ruby-throated hummingbirds is the wild spotted touch-me-not of wet places.  Highbush cranberry shrubs have clusters of mostly bright red fruit, and wild plums are ripe.  Dahlias, and garden and shrub roses are blooming nicely.  Native basswood tree leaves are showing some golden-yellow autumn color, and poison ivy foliage is displaying reds and yellows.  Tiny, newly hatched snapping turtles head for ponds and lakes.  White-tailed deer fawns have grown quite large and are losing their spots.

On Aug. 23 a year ago
We began the day with an early morning thunderstorm and strong winds.  The day ended up being partly sunny and humid with a high of 87 degrees.  Field corn was starting to dent (this year it started Aug. 1).  Wild cucumber, featuring clusters of white flowers, was very showy.  This annual vine climbs up trees, and grows across shrubs and along fences.

Jim Gilbert’s “Nature Notes” is an occasional feature of Sun Patriot Publications.