Nightjars are fascinating birds and fierce hunters. With their mottled earth-colored feathers, they spend most of the day on the ground or resting on a tree limb. They are perfectly camouflaged, blending flawlessly into their surroundings. They are motionless during the day because, for them, nighttime is for hunting.
Nightjars hunt at night using their excellent eyesight to find insects. Nightjars have incredible agility in the air, which allows them to scoop up swarms of insects with their large mouths.
There are 83 species of nightjars worldwide, but only eight species in North America. They are all nocturnal, active at night, or crepuscular, active during twilight and their diets and hunting habits are similar.
If you want to learn more about how nightjars hunt, please read on.
What Do Nightjars Eat?
Nightjars are insectivores, which means their diet consists mainly of insects. Eating various insects, their diet comprises mosquitoes, beetles, midges, blackflies, moths, flying ants, spiders, mayflies, wasps, grasshoppers, and more. They prefer to eat swarms of insects to exert less energy.
Nightjars have also earned the name “goatsucker” from a long-ago myth surrounding their feeding habits. It is said that nightjars would fly in and feed on female goats’ udders, sucking the milk. They did swoop, but this was to eat flies and bugs swarming around the goats.
How Do Nightjars Hunt?
Nightjars, nocturnal and crepuscular, hunt for food mostly near dusk or dawn. They are ‘twilight’ hunters, hunting before daylight or before sunset.
Nightjars possess great agility in flight, allowing them to catch insects in their large mouths while cruising along. The back of the nightjar’s mouth opens two inches in width, which is wider than its length, but their mouths open vertically and horizontally.
This allows the bird to swoop past and scoop up its prey while soaring through the air. They fly out from perches or on the ground, usually into open areas such as meadows or pastures.
Another factor plays a role in helping the food into a nightjar’s mouth. They have large mouths but also fly into large masses of flying insects.
When residing around cities, they will fly under street lights like moths, and other insects are drawn to the light. Besides hunting, their mouths make excellent drinking cups, allowing them to soar low over ponds and lakes, drinking in freshwater as they fly by.
Each nightjar possesses small bristle-like feathers over the sides of each eye. These serve a twofold purpose. One is to help push the food into their mouths, and the other protects their eyes. The latter is very helpful when flying into all of those insects. Imagine just how many insects you can see under a streetlight. This is another advantage for nightjars that live in cities hunting around lamp posts. The bugs are illuminated in the darkness.
During their hunting maneuvers, they will dive abruptly from above the treetops and flex their wings when coming out of a dive. Air moving across the wingtips will create a booming sound. This is mainly performed by males, possibly to attract females.
Bats hunt in a similar way to nightjars, also seizing insects out of the sky. The difference between the two is that bats locate prey by sound using hearing, and nightjars rely on sight using their eyes.
The nightjar’s visual field is excellent because of how their eyes are situated on either side of their head. The nightjar’s vision is sharp, and their eyes are ideally suited for low light but are not so good in daylight.
The nightjar will sometimes eat its prey on the fly. Sometimes when snatching bigger insects such as grasshoppers or large beetles, they will take them back to their perch where they may break them up before eating, although they may swallow them whole.
How Does Weather Affect The Nightjar Hunting?
Lousy weather also diminishes a nightjar’s vision. They are dependent on good, clear weather when hunting. Moonlight, especially a full moon, is ideal. Weather conditions are best with warm, dry evenings to maximize hunting.
Weather conditions have to be suitable for the nightjar when hunting. They don’t hunt during the day, and if the weather at night is cloudy, rainy, or very windy and cold, the nightjar cannot hunt and, therefore, cannot eat.
If several days go by with lousy weather, it is believed that the nightjar can induce a state of torpor. Torpor is a physiological change in the body where they can lower their temperature, slowing their metabolism down when conditions are unfavorable for hunting.
Torpor saves energy when food is not readily available or the temperature is too low. It is, in a way, similar to hibernation but torpor does not last months like hibernation. Torpor only occurs when conditions for hunting are unfavorable.
Like many other birds, nightjars migrate in the fall to the tropics as cold weather means much fewer insects. For eating and hunting, nightjars need to travel where the food is.