Caprimulgidae – Nightjars & Nighthawks

The Caprimulgidae or nightjars, the only family of Caprimulgiformes, are medium-sized nocturnal or crepuscular family characterised by long wings, short legs and very short bills. They are sometimes called goatsuckers, due to the ancient folk tale that they sucked the milk from goats (the Latin for goatsucker is Caprimulgus). Some New World species are called nighthawks, poorwills and etc. Nightjars usually nest on the ground. The English word ‘nightjar’ originally referred to the European Nightjar Caprimulgus europaeus.

Caprimulgids are perhaps best known for their distinctive calls that punctuate the night. Their nocturnal habits, cryptic plumage, and often-camouflaged eggs leave much unknown about the breeding habits or conservation status of many species. Nightjars and nighthawks find their prey of nocturnal insects by sight even in the dimmest of light levels. Sight clearly plays an important role in mate-finding, too, as sexual selection in these birds of the night has led to a diversity of visual signals, including long tail plumes or rackets from wing feathers in males. Their jarring calls have earned them the common name of nightjars.

Square-tailed Nightjar Caprimulgus fossii – ©Dubi Shapiro

Previously, all members of the orders Apodiformes, Aegotheliformes, Nyctibiiformes, Podargiformes, and Steatornithiformes were lumped alongside nightjars in the Caprimulgiformes. In 2021, the International Ornithological Congress redefined the Caprimulgiformes as only applying to nightjars, with potoos, frogmouths, oilbirds, and owlet-nightjars all being reclassified into their own orders.  A phylogenetic analysis found that the extinct family Archaeotrogonidae, known from the Eocene and Oligocene of Europe, are the closest known relatives of nightjars.

Least Nighthawk Chordeiles pusillus – ©Dubi Shapiro

Traditionally, nightjars have been divided into two subfamilies: the Caprimulginae, or typical nightjars and the Chordeilinae. The Chordeilinae included species with short bills and lack of elongated rictal bristles in the genera Nyctiprogne, Lurocalis and Chordeiles. Molecular phylogenetic studies have shown that the two subfamilies are not monophyletic. In addition, the subfamily Eurostopodinae was introduced for species in the genera Eurostopodus and Lyncornis but these two genera are now known not to be closely related.

Madagascan Nightjar Caprimulgus madagascariensis – Dubi Shapiro©

Caprimulgids are found around the world in all continents except Antarctica. They are mostly active in the late evening and early morning or at night, and feed predominantly on moths and other large flying insects. They are not known to live in extremely arid desert regions. Nightjars can occupy all elevations from sea level to 4,200 m (13,800 ft), and a number of species are montane specialists. However, nightjars occupy a wide range of habitats, from deserts to rainforests but are most common in open country with some vegetation.

Long-tailed Nightjar Caprimulgus climacurus – ©Dubi Shapiro

The nighthawks are confined to the New World, and the eared nightjars to Asia and Australia. A number of species undertake migrations, although the secretive nature of the family may account for the incomplete understanding of their migratory habits. Species that live in the far north, such as the European nightjar or the common nighthawk, migrate southward with the onset of winter. Geolocators placed on European nightjars in southern England found they wintered in the south of the Democratic Republic of the Congo. Other species make shorter migrations.

Sand-coloured Nighthawk Chordeiles rupestris – ©Dubi Shapiro

Most have small feet, of little use for walking, and long pointed wings. Their soft plumage is cryptically coloured to resemble bark or leaves. Some species, unusual for birds, perch along a branch, rather than across it. This helps to conceal them during the day.

White-tailed Nightjar Hydropsalis cayennensis – ©Dubi Shapiro

The Common Poorwill, Phalaenoptilus nuttallii, is unique as a bird that undergoes a form of hibernation, becoming torpid and with a much-reduced body temperature for weeks or months, although other nightjars can enter a state of torpor for shorter periods.

Buff-collared Nightjar Antrostomus ridgwayi – ©Dubi Shapiro

Nightjars lay one or two patterned eggs directly onto bare ground. It has been suggested that nightjars will move their eggs and chicks from the nesting site in the event of danger by carrying them in their mouths. This suggestion has been repeated many times in ornithology books, but while this may accidentally happen, surveys of nightjar research have found very little evidence to support this idea.

Collared Nightjar Gactornis enarratus – ©Dubi Shapiro

Some species of nightjars are threatened with extinction. Road-kills of this species by cars are thought to be a major cause of mortality for many members of the family because of their habit of resting and roosting on roads.