The nightjar is a medium-sized nocturnal bird that belongs to the Caprimulgidae family. It is known by several common names including nightjar, nighthawk, nightchurr, goatsucker, and more. The name “nightjar” refers to their largely crepuscular or nocturnal activity patterns and their familiar song or “churring” sounds. There are over 100 species of nightjars found worldwide, except for the polar regions and some oceanic islands.
Physical Description
Nightjars are cryptically colored birds with soft plumages in shades of brown, grey, or rufous. This provides them with excellent camouflage as they roost during the day. They have short legs, very short bills, and wide gapes. Their eyes are large which gives them enhanced vision in low light conditions. Nightjars have long pointed wings and long tails which provides them with fast and agile flight. They also have unique comb-like structures called ectoparasitic fringe or pectinations on the middle claw that may help them groom and maintain feathers.
Males can often be distinguished from females by the presence of white patches or spots on the tail and wings. Size ranges from about 16-24 cm in length and 32-56 cm in wingspan depending on the species. The common nighthawk is one of the smallest species with a body length of 19-22 cm while the great eared-nightjar is one of the largest at 38-46 cm long. Weight ranges from about 50-125 grams.
Distribution and Habitat
As earlier mentioned, nightjars have a worldwide distribution but are absent from polar regions and some oceanic islands. They are found throughout Europe, Asia, Africa, Australasia, and the Americas. Their preferred habitats are open woodlands, savannas, scrublands, and forests. Some species thrive in degraded former forests. Being nocturnal, nightjars typically roost and nest on the ground or perched lengthwise along a branch during the day. At night, they are active mostly in open areas where they hawk for insects.
Diet and Hunting
Nightjars are insectivorous, meaning they primarily eat insects and other arthropods. Their diet includes moths, beetles, crickets, grasshoppers, cicadas, ants, flies, and more. They hunt from dusk to dawn by hawking where they fly around with their mouth wide open to catch insects. Their wide gape allows them to eat larger insects than other insect eating birds. Nightjars also drink by skimming the surface of water bodies while flying.
Some species are known to occasionally eat fruits, seeds, and small vertebrates such as frogs, lizards, small birds, and even bats. For example, the common nighthawk sometimes preys on migrating songbirds during their spring and fall migrations.
Reproduction and Life Cycle
The breeding season for nightjars depends on the species and location but generally coincides with increased insect activity. Courtship includes aerial chases and diving displays. Males of some species have ornamental tail feathers or bright patches used to attract females.
Nightjars don’t build nests. Instead, they rely on camouflage and their cryptic plumage to avoid detection. Eggs are simply laid on bare ground or dead leaves. Nest sites are typically in shaded locations like near a rock, log, tree stump, or bush. Clutch size ranges from 1-4 eggs depending on the species. Incubation lasts 16-20 days.
The eggs are elliptical and creamy or pinkish buff colored with grey and brown blotches for camouflage. Both parents incubate the eggs and care for the young. After hatching, the helpless and downy chicks stay in the nesting area where the parents continue to care for them. Chicks can make short flights at 16-17 days old and become fully independent a few weeks later. Nightjars are primarily monogamous and may even renest or double brood after successful first broods.
Migration
Many nightjars migrate long distances between their breeding and wintering habitats. Migration occurs at night when atmospheric conditions support long distance flight. Some migrations span thousands of miles over oceans. For example, the common nighthawk migrates between Canada and South America. Nightjars migrating over the ocean between Europe and Africa are known to stopover on ships to rest. Navigation seems to rely on a combination of celestial and geomagnetic cues.
Threats and Conservation Status
Habitat loss poses the greatest threat to nightjar populations globally. Other threats include climate change, predation, vehicle collisions, human disturbance of nesting sites, and pesticides reducing insect food supplies. Some species of nightjars are considered threatened or near threatened by the IUCN Red List including the least pauraque, Puerto Rican nightjar, and Egyptian nightjar. Creating protected habitat areas and minimizing anthropogenic threats can help conserve nightjar populations.
Significance to Humans
Nightjars play an important role in controlling insect pest populations. They were once thought to drink milk from goats at night, leading to the misnomer “goatsucker”. Their cryptic camouflage, haunting sounds, and elusive nature have also led to myth, superstition, and lore across many cultures. Today they help draw interest and tourism from birdwatchers seeking to spot these enigmatic birds of the night.
Major Species of Nightjar
There are over 100 recognized species of nightjars divided into several genera including:
Common Nighthawk
The common nighthawk (Chordeiles minor) is a nightjar species found throughout North and South America. Its habitat includes open woodlands, logged forests, savannahs, rocky barrens, deserts, and urban areas. It measures 19-22 cm in length with a wingspan of 48-54 cm and weight of 50-75 grams. Plumage is cryptic brown, black, and grey. This is one of the most common and widespread nightjar species in the Americas.
European Nightjar
The European nightjar (Caprimulgus europaeus) breeds across most of Europe and temperate Asia. As the name suggests, it is widespread across Europe in habitats like heathland, forest clearings, and grasslands. Length ranges from 23-26 cm with a 55-60 cm wingspan. It is larger than the common nighthawk. European nightjars winter in Africa. Males can be recognized by their white wing patches.
Egyptian Nightjar
The Egyptian nightjar (Caprimulgus aegyptius) is found in parts of North Africa and the Middle East. Natural habitats include rocky deserts, dry savannahs, and scrublands. It is a medium-sized nightjar around 24 cm in length. Plumage is sandy brown mottled with black, grey, and tawny. It is considered a vulnerable species threatened by habitat loss.
Puerto Rican Nightjar
The Puerto Rican nightjar or nocturnal ground-dove (Antrostomus noctitherus) is an endangered species endemic to Puerto Rico. It inhabits limestone cave openings, karst forests, and shade coffee plantations in the island’s karst belt. Length is about 22 cm. It is threatened by habitat loss and predation. Only 200-400 individuals remain in the wild.
Spot-tailed Nightjar
The spot-tailed nightjar (Eurostopodus argus) occurs in parts of Australia and New Guinea. It inhabits eucalyptus woodlands and forests. The species measures 20 cm in length and bears cryptic grey, black, and brown plumage. Distinctive white tail spots help identify the species. It is not considered threatened.
Pennant-winged Nightjar
The pennant-winged nightjar (Macrodipteryx vexillarius) is found in parts of sub-Saharan Africa. As the name suggests, males have unique wavy, pennant-shaped wing feathers. Length reaches about 22 cm. Habitats include dry savannahs and open woodlands. The IUCN classifies this species as near-threatened.
Frequently Asked Questions
What do nightjars eat?
Nightjars are primarily insectivorous, feeding on insects like moths, beetles, flies, ants, and more that they catch during flight. Some nightjars may occasionally eat other arthropods, fruits, seeds, or small vertebrates.
Why are they called nightjars?
They are named nightjars because of their largely nocturnal activity patterns and the peculiar “jarring” or “churring” sounds males make during breeding season to attract mates or defend territories.
When are nightjars active?
Most species of nightjars are crepuscular or nocturnal, meaning they are active at dawn and dusk or during the night. This coincides with peaks in insect activity making hunting easier. During the day, nightjars typically roost camouflaged on the ground.
How many eggs does a nightjar lay?
Clutch size ranges between 1-4 eggs depending on the nightjar species. For example, common nighthawks and European nightjars lay two eggs per clutch on average. Larger species may lay up to 4 eggs. The eggs are cryptically colored for camouflage.
Why are nightjars threatened?
Habitat loss poses the greatest threat to nightjars. Other risks include climate change, predation, collisions with vehicles, human disturbance, and reduced food supply due to pesticides. Several species are threatened or endangered due to these factors.
Where do nightjars nest?
Nightjars nest on the bare ground relying on camouflage for protection. They do not build nests. Nest sites are typically sheltered spots like near rocks, stumps, bushes, or logs. The ground coloration helps the eggs escape detection.
Conclusion
In summary, nightjars are a fascinating family of nocturnal and crepuscular birds perfectly adapted to hunting insects at night. Their cryptic plumage, wide gapes, sensitive hearing, and agile flight make them expert aerial insectivores. While elusive, nightjars play an important ecological role in regulating insects. They also have cultural significance and draw interest from birders. However, many species now face threats from habitat loss and other factors. Increased conservation efforts are needed to protect their populations. Their mystery and allure will continue to fascinate humans well into the future.