By John L. Turner

At dusk on Oct. 6 volunteers with the Four Harbors Audubon Society (4HAS), a local chapter of the National Audubon Society, concluded their fifth year of conducting the Nighthawk Watch and as like the previous four years, this year’s tally brought new wrinkles to the unfolding story of nighthawk migration. 

1,819 Common Nighthawks were seen this year at the Stone Bridge Nighthawk Watch, located at the southern end of Frank Melville Memorial Park in Setauket. The season started off slow but picked up in the latter third, similar to what happened in 2019; the 2021 total is less than the previous four year totals of: 2,046 in 2017, 2,018 in 2,018, 2,757 in 2019, and 2,245 in 2020.

You might reasonably ask: Why establish the Stone Bridge Nighthawk Watch to count Common Nighthawks, a species related to the more familiar Whip-poor-will?

Well, first of all its fun and entertaining and great camaraderie developed among the regular participants. Nighthawks are quite distinctive in flight and can be downright mesmerizing to watch when they’re in active feeding mode, erratically darting to and fro in pursuit of aerial insects with their white wing blazes flashing.

Second, the watch provides an educational opportunity by allowing members of 4HAS to engage with people walking by, informing them about the status of nighthawks, the threats they and other birds face, and wildlife and environmental issues generally. In this way nighthawks can provide the opportunity for a broader discussion about conservation, the condition and fate of the planet and all its member species. 

Third, it’s our hope that as the years pass, we’ll assemble a useful set of data, an additional source of information, that can help researchers develop a more complete picture about nighthawk population trends.

We know that the current picture is a troubled one for nighthawks and other birds, like swallows, swifts, and flycatchers that feed on aerial insects (these insect-eating birds are referred to as aerial insectivores). 

The continent-wide Annual Breeding Bird survey documented a two-percent decline in nighthawks from 1966 through 2010, resulting in a 60% decline in overall number nighthawk numbers; this means for every ten nighthawks there were in 1965, there are four today. The main culprit? A reduction in the amount of aerial insects such as gnats, midges, beetles and bugs, moths, and mosquitoes. 

This reduction has been noticed by a lot of people at least as evidenced by anecdotal stories. Mine includes two: Growing up in Smithtown in the 1960’s I remember, when driving any significant distance on Long Island, my father needed to clean the windshield with wiper fluid every once in a while to remove the countless smudges caused by hundreds of insects colliding with the windshield. Today, I can drive all day around Long Island without the need to do the same.

The second is the significant reduction in the number of moths and other night-flying insects attracted to the lights of local ball fields. I vividly remember watching, in the 1960’s and ’70’s many nighthawks zooming around the lights at Maple Avenue Park during night softball games, feeding on moths. Not so today, with significantly fewer moths and other insects attracted to the ball-field lights. For example, in three visits over the past decade in the month of September to night games at the stadium where the Long Island Ducks play,  I’ve seen a total of one nighthawk.

Another cause is loss of breeding habitat, involving two types — natural areas being converted to agriculture, shopping centers, and housing and loss of suitable rooftops. This latter “breeding habitat” illustrates the habit of nighthawks nesting in urban areas using gravel rooftops which mimic the natural and open substrates they often nest on in natural settings. Unfortunately, gravel roofs are being replaced by sealed rubber roofs which do not provide nighthawks with suitable nesting substrate.

Being dependent on aerial insects, nighthawks leave the northern hemisphere, as temperatures cool and insects decline and ultimately disappear, to overwinter in South America, especially in and around the Amazon River basin and the adjacent Cerrado savanna/grassland region to the southeast. Generally, fall-migrating nighthawks in North America head southeast, leaving the continent either by crossing the Gulf of Mexico or heading south through Florida and passing over the Caribbean to South America. 

For reasons that are not clear, nighthawks from the western United States and Canada head southeast too, rather than what appears to be the shorter route of heading directly south, staying over land through Mexico and Central America. The nighthawks that fly over us at the Watch are birds heading more directly south coming from New England and eastern Canada and generally continuing south to join other nighthawks in Florida before continuing on. Some though, appear to shortcut the southbound journey by venturing out over the Atlantic Ocean.

The 2021 daily totals of nighthawks generally followed numbers from past years with more nighthawks passing by during the first half of the count period. The top daily tally was 169 birds, occurring on Sept. 12 and we had six nights with one hundred or more birds. We had only one evening with no nighthawks — the day when the remnants of Hurricane Ida passed through Long Island.

We saw many other interesting things besides flitting nighthawks while spending 41 days standing on the Stone Bridge ­— ­ beautiful sunsets and sometimes dramatic and foreboding skies; many clouds, some shaped like animals; one rainbow; the planets of Venus, Jupiter (and the four Galilean moons), and Saturn all seen through a 60x birding scope; several Bald Eagles including a low-flying white-headed adult; many Ospreys and other birds-of-prey; flights of Great Blue Herons and American and Snowy Egrets; a steady stream of Double-crested Cormorants almost always heading from the northeast to the southwest; a daily rush of blackbird flocks that plunged into the protective reeds of Conscience Bay; a daily dose of a pair of kingfishers; occasional songbirds flitting about in nearby trees; and on most nights when dusk settled over the ponds, a few Red and Brown Bats ceaselessly swooping in erratic loops, lines and circles over the surface of the pond.

So, if you already possess your 2022 calendar, circle Aug. 27, the date we’ll return to the Stone Bridge to once again watch the daily aerial ballets of Common Nighthawks. As always, they’ll be urged by instinct to move south, passing over Long Island, through the southeastern United States to cross the equator, where they’ll spend many months feeding in the balmy skies of South America, enjoying their “perpetual summer” existence.

A resident of Setauket, John Turner is conservation chair of the Four Harbors Audubon Society, author of “Exploring the Other Island: A Seasonal Nature Guide to Long Island” and president of Alula Birding & Natural History Tours.