Nightjars are highly specialised feeders, relying on their exceptional hunting skills to thrive in the twilight hours. Spotting a Swamp Nightjar may require a keen eye, as its mottled grey and brown feathers mirror the twilight hues of its habitat. The Swamp Nightjar is a creature of the night, coming alive as the sun sets.
General Diet of Nightjars
Nightjars primarily feed on flying insects, with moths and beetles forming the bulk of their diet. These birds are opportunistic feeders, consuming a variety of flying insects depending on availability. While moths and beetles are their staple food, they also eat flies, wasps, and other nocturnal insects.
- Insect Variety: Nightjars consume a wide range of insects, showcasing their adaptability to different environments and prey availability.
- Nocturnal Feeding: As nocturnal hunters, nightjars target insects that are active during the night.
Feeding Habits
Nightjars exhibit unique feeding behaviors that enable them to efficiently capture insects in flight.
- Aerial Hunters: Nightjars are adept at catching insects mid-air, using their wide mouths and agile flight.
- Crepuscular Activity: Foraging birds emerge in the late afternoon or directly after sunset for crepuscular feeding and are once again active before sunrise.
- Nightjars may feed at any time of the day (especially if it is overcast) or at night (with a full moon or near street lighting).
- At dusk, they often fly around livestock to feed on insects swarming around the animals.
- Nightjars may also forage under the canopy by flying from favored perches catching insects at foliage heights of 5 - 15 feet (~1.5 - 5 m).
- Larger insects are usually taken back to their favored feeding perches. While holding the insects in their bills, nightjars keep the head upright, shake and swallow the prey whole, or they may break the insects apart before eating.
- Insects may also be taken from the ground or foliage.
- During the breeding season, they hunt like pewees-sitting on an elevated perch, sallying out in a 5-10 second long flight to catch an insect, and then returning to the same perch. Breeding birds forage like this for several hours after sunset, and again in the hour before dawn.
- Buff-collared Nightjars spend the day roosting on the ground, typically under small bushes on hillsides, with their head pointed downslope. They forage during the night and are most active at dawn and dusk.
Specific Nightjar Species and Their Diets
The nightjar family is a diverse group, and different species have adapted to their specific environments.
Swamp Nightjar (Caprimulgus natalensis)
As a nocturnal hunter, the Swamp Nightjar feeds on a variety of insects. Breeding coincides with the rainy season to ensure ample insect prey for their offspring. The Swamp Nightjar employs a minimalistic breeding strategy, laying eggs on the ground amidst dense underbrush to utilize natural camouflage.
Read also: Learn how Don Brewer got his start
Buff-collared Nightjar (Antrostomus ridgwayi)
Buff-collared Nightjars feed on nocturnal flying insects such as moths and beetles.
- Habitat: Buff-collared Nightjars often occur in canyons, desert washes, and other dry habitats with dense shrubs and short trees. They also inhabit deciduous forest and moist pine-oak woodlands.
- Behavior: Breeding birds in southeastern Arizona sing and forage from perches 1-2.5 meters (3-8 feet) off the ground, but nonbreeding birds observed in Mexico make foraging flights almost exclusively from the ground.
Nubian Nightjar (Caprimulgus nubicus)
Like other nightjars, it is a nocturnal aerial insectivore, feeding mainly on moths and other flying insects.
Common Nighthawk
This widespread and familiar bird may hunt by day or night, catching flying insects in the air.
- Forages most actively near dusk and dawn, also during the day and at night, perhaps especially on moonlit nights.
- Forages mostly in flight, scooping up flying insects in its wide, gaping mouth.
- Will feed around bright lights at night, taking the insects attracted there.
- May rarely take insects from the ground.
- Insects: Feeds mainly on flying insects, including beetles, moths, grasshoppers, and many others. Will feed heavily on swarms of winged ants or termites.
Pennant-winged Nightjar (Caprimulgus vexillarius)
Their diet includes a variety of insects although scarab beetles are favoured. They drink while flying slowly over a water surface. Foraging birds emerge in the late afternoon or directly after sunset for crepuscular feeding and are once again active before sunrise.
Chick Diet
In the wild, the parent birds provide their chicks with a steady supply of regurgitated insects, which are easier for the chicks to digest.
Read also: The Hoxsey Diet
Adaptations for Feeding
Nightjars have several adaptations that make them efficient insectivores.
- Wide Mouth: The beak has evolved to be much wider than it is long, and it opens wide both - vertically as well as horizontally.
- Rictal Bristles: Caprimulgus species have relatively long bills and rictal bristles.
- Nocturnal Vision: Their vision is adapted for low-light conditions, enabling them to hunt effectively at night.
- Aerodynamic Capabilities: Nightjars measure approximately 26 to 28 centimetres in length, with a wingspan ranging from 57 to 64 centimetres. This large wingspan relative to their body size is a key adaptation that allows them to glide efficiently and conserve energy during their nocturnal hunting flights. In addition to their wingspan, the Nightjar’s body shape is streamlined, with long, pointed wings and a relatively short tail, which further enhances their aerodynamic capabilities.
Conservation Concerns
Nightjars face several challenges and are currently classified as birds of conservation concern in some regions.
- Habitat Loss: The primary threats to Nightjars include habitat loss and fragmentation. These birds require specific habitats such as heathland and young coniferous forests for breeding.
- Pesticide Use: Declining seriously in numbers in many parts of North America. Causes may include changes in land use and overuse of pesticides.
Observing Nightjars
Nightjars are best observed in the UK during the summer months. During this period, they can be found in a variety of habitats, including heathlands, moorlands, and young coniferous forests. One of the most well-known locations for spotting Nightjars is the New Forest in southern England, where large populations return each year to breed. Nightjars are also known to frequent areas near human habitation, particularly where there is open ground or heathland.
Identification Tips
- Auditory: Nightjars are best identified by their distinctive churring call at night.
- Visual: Visually, they have mottled brown and grey plumage, long wings, and a flat head. Males have white spots on their wings and tail.
Additional Information
- Migration: Yes, Nightjars are migratory birds. In the UK, they typically arrive in late April or May and depart for Africa in August or September.
- Lifespan: Nightjars typically live for about 4 to 6 years in the wild, although some individuals have been recorded living up to 12 years under favourable conditions.
- Weight and Size: An adult Nightjar typically weighs between 65 to 100 grams, depending on various factors such as age, sex, and the time of year. The weight of a Nightjar can also fluctuate based on the availability of food.
Caprimulgus Genus
Caprimulgus is a large and very widespread genus of nightjars, medium-sized nocturnal birds with long pointed wings, short legs and short bills. Caprimulgus is derived from the Latin capra, "nanny goat", and mulgere, "to milk", referring to an old myth that nightjars suck milk from goats.
- Caprimulgus nightjars are found around Afro-Eurasia and Australasia, and like other nightjars they usually nest on the ground.
- Most have small feet, of little use for walking, and their soft plumage is cryptically coloured to resemble bark or leaves.
- Some species, unusually for birds, perch along a branch, rather than across it, which helps to conceal them during the day.
Etymology
The genus Caprimulgus was introduced in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae. The type species is the European nightjar (Caprimulgus europaeus). The name is the Latin word for a nightjar; it combines capra meaning "nanny goat" and mulgere meaning "to milk". The myth that nightjars suck milk from goats is recounted by Pliny the Elder in his Natural History: "Those called goat-suckers, which resemble a rather large blackbird, are night thieves.
Read also: Walnut Keto Guide