Keep your eyes to the skies this Labor Day Weekend as swarms of nighthawks migrate south! The Common Nighthawk is a seldom encountered species in Maine — most Mainers will be more familiar with their cousin, the vocal Eastern Whip-poor-will — but in late August we see a spike in their sightings as large groups forage and migrate together.
Most large movements are reported in the early evenings, typically an hour or two before dusk. They are often seen traveling along river valleys or coastal routes but anecdotal evidence indicates they might also follow major roads. Nighthawks will feed while migrating so they will often linger in an area with lots of aerial insects, especially flying ants (which appear to be abundant recently). Here is a quick video of a large group I had over River Road in Windham yesterday (29 August 2019):
I’ve enjoyed picking through these flocks, attempting to age/sex individuals since local Maine birder Louis Bevier shared tips on this back in 2014 on the Maine-birds listserv. Unfortunately the photos/text he shared is no longer visible as photo sharing through flickr has changed, so here is my very quick primer on Common Nighthawk aging/sexing in flight:
Adult Male: Adults of both sexes show pale crescents on their throat but this appears whiter on males. Males also have white subterminal bands on their tails (see below). The white wing patches tend to be larger and cleaner white on males but I honestly have trouble distinguishing this, especially in the field, but the aforementioned field marks are easier to spot.
Adult Female: Similar to the adult male (described above) but note the typically buffier color on the throat crescent. Also, females generally lack the white subterminal that is distinctive on males (note the very limited white tail band in the female photo at the beginning of this article).
Juvenile: No white or buff in the throat. White wing patches are smaller than adult males but can apparently overlap with some adult females.
You can check eBird for sightings near you by following this link: 2019 Common Nighthawk sighting in Maine
Have a safe and birdy Labor Day weekend!