Thanks to John Tschopp for sharing his August 21 sighting of Common Nighthawks around Anderson Road, near Spiering’s Automotive, at 7pm.
“A flock of between 20 to 30 birds was feeding madly on flying insects.”
Here’s the lowdown on the common nighthawk, thanks to Wikipedia:
The Common Nighthawk (Chordeiles minor) is a medium-sized  crepuscular or nocturnal bird, whose presence and identity are best revealed by its vocalization. Typically dark (grey, black and brown), displaying cryptic colouration and intricate patterns, this bird becomes invisible by day. Once aerial, with its buoyant but erratic flight, this bird is most conspicuous. The most remarkable feature of this aerial insectivore is its small beak belies the massiveness of its mouth. Some claim appearance similarities to owls. With its horizontal stance and short legs, the Common Nighthawk does not travel frequently on the ground, instead preferring to perch horizontally, parallel to branches, on posts, on the ground or on a roof. The males of this species may roost together but the bird is primarily solitary. The Common Nighthawk shows variability in territory size.
This caprimulguid has a large, flattened head with large eyes; facially it lacks rictal bristles. The Common Nighthawk has long slender wings that at rest extend beyond a notched tail. There is noticeable barring on the sides and abdomen, also white wing-patches.
The Common Nighthawk measures 22 to 25 cm (8.7 to 9.8 in) long, displays a wing span of 51 to 61 cm (20 to 24 in) weighs 55 to 98 g (1.9 to 3.5 oz), and has a life span of 4 to 5 years.