At dusk during the summer the silence is broken by loud “booming” sounds as medium-sized birds begin to fly erratically around the pastures surrounding our house. The source of this unusual noise is the common nighthawk (Chordeiles minor), which resembles a large bat as it flits to and fro.
The common nighthawk flies to a moderate height then dives to the ground. Five or six feet above the ground it suddenly turns upward, flexing its wings downward at the same time. This causes air to vibrate through the primary feathers causing the deep “boom” sound. Truthfully, although the sound is described as a “boom” in the guide books and literature, it sounds more like a loud “whoopie cushion” to me. The male makes this courting display to attract females during the breeding season. Later in the summer the booming dive is directed at young nighthawks, intruders and even humans. For me the nighthawk booms are a sound of summer.
Common nighthawks, also called bullbats, are largely nocturnal and well camouflaged during the day. Therefore they are not as well studied and understood as other birds. Normally solitary, nighthawks will forage or migrate in small groups of two or three. (Usually in the evening we see several flying in various parts of our fields.)
Common nghthawks are black to paler brownish-gray on the upper parts while the underparts are barred blackish-brown to white/buff. The color patterns camouflage the nighthawk during the day as it perches. Males have a white throat patch, a white subterminal tailband and a white primary patch halfway from the bend of the wing to the wing tip. Females have a buff throat patch, no tail band and a smaller primary patch on the wings. The short legs and small feet reflect its aerial lifestyle. The wings are long and pointed and the tail is notched. Although the bill of a nighthawk is small, the gape is wide and opens into a cavernous mouth. Insects are engulfed in this huge mouth and swallowed whole.
A resident of open grasslands, the common nighthawk is an insectivore eating moths, beetles, and cicadas as well as other nocturnal insects.
Common nighthawks are strongly migratory, spending winters in Argentina and Brazil and the breeding season throughout North America. Nighthawks are one of the later birds to arrive in our area (Modoc County CA), usually making their appearance in early June.
An interesting bit of folklore: Nighthawks belong to the family Caprimulgidae, which also includes nightjars. All the members of this family are collectively called goatsuckers. Because of their nocturnal and secretive habits, huge mouths, strange vocalizations and tendency to forage around livestock, these birds were thought to suckle goats. Over time this superstition became widespread and even today the caprimulgids are called goatsuckers.
We see and hear common nighthawks almost every night during the summer. However, because they are nocturnal, fly so erratically and are well hidden during the day I have been unable to get any pictures of nighthawks. I was lamenting to Leonard the fact that I could not get a nighthawk picture when, sadly, a friend came by the next day with a dead nighthawk. He hit it while driving the previous night (County Road 91 near Lookout CA) and wanted Leonard to identify the bird for him. Unfortunately that was not how I wanted to get a common nighthawk picture. With a buff throat patch and no tail band, this is a female specimen.