Caprimulgidae: Nightjars

Puerto Rican Nightjar.  © Michael J. Morel

The nightjars are a large family of nocturnal insectivores that spend their daylight hours quietly blending into the background.  A small number are well known for their distinctive vocalizations—the Eastern Whip-poor-will (Antrostomus vociferus) is the prime example—but a larger number are obscure birds that are rarely heard or seen even by those who actively try to find them.  The family also includes the nighthawks, which are not exclusively nocturnal, and are instead usually termed crepuscular (most active at dawn and dusk) although this does not fully describe their activity patterns.

Puerto Rican Nightjar.  © Guillermo J. Plaza

Nightjars are most numerous and diverse in the tropics, both Old World and New World, with a few species that migrate to temperate and subarctic zones during the summer months.  They inhabit a wide range of habitats, including forests, open woodlands, swamps, scrub, grasslands, and deserts, so are nearly omnipresent in warm climates, but are rarely diverse in any particular location.

Identification

Nightjars are generally heard more often and more clearly than they are seen, so vocalizations tend to be the primary mode of observation and the best way to identify species.  The family as a whole shares approximately the same body shape and cryptic plumage, and they are most often seen fleetingly in low light, so most sightings do not provide diagnostic details.

Most nightjars and nighthawks belong to groups of very similar-looking species, and in several cases the internal variability within species is far more pronounced than the differences between species.  In many cases, vocalizations are indispensable to identification—even a roosting bird studied carefully at close range in broad daylight might not be identifiable based solely on its visible features.

In many groups of species, the patterns of white or buff on the tail feathers differ consistently enough to be reliable for identification, but most species are not uniform in these patterns, so the illustrations in field guides do not always provide reliable guidance.  Illustrations are especially unreliable in their representations of the camouflage in nightjar plumages, as both coloration and pattern vary widely within most species.  For an example of such variation within a single species, compare the details of pattern and coloration in these photos of female Antillean Nighthawks:

Antillean Nighthawk.  © Luiz Gonzalez

Antillean Nighthawk.  © Dax Román

Antillean Nighthawk.  © Wayne Fidler

Antillean Nighthawk.  © Dax Román

Taxonomy

The species-level taxonomy of the Caprimulgidae is mostly settled, with lingering doubts about a handful of complex cases and a reasonable likelihood that a few additional species remain as yet undiscovered.  As currently understood, the family comprises approximately 97 to 106 species (plus one recently extinct) in two subfamilies:

Chordeilinae: Nighthawks (20 to 21 species)

Caprimulginae: Nightjars (77 to 85 species, plus one extinct)

The primacy of vocalizations in distinguishing nightjar species applies both to field identification by humans and the birds’ mutual recognition, which makes taxonomic judgments about geographically separate populations more objective than it is in many other bird families—although the research on vocalizations remains incomplete or inconclusive in some cases.

Spotted Nightjar (Eurostopodus argus)

White-throated Nightjar (Eurostopodus mystacalis)

Solomons Nightjar (Eurostopodus nigripennis)

New Caledonian Nightjar (Eurostopodus exul)

Satanic Nightjar (Eurostopodus diabolicus)

Papuan Nightjar (Eurostopodus papuensis)

Archbold’s Nightjar (Eurostopodus archboldi)

Malaysian Eared Nightjar (Lyncornis temminckii)

Great Eared Nightjar (Lyncornis macrotis)

Collared Nightjar (Gactornis enarratus)

Nacunda Nighthawk (Chordeiles nacunda)

Least Nighthawk (Chordeiles pusillus)

Sand-colored Nighthawk (Chordeiles rupestris)

Lesser Nighthawk (Chordeiles acutipennis)

Common Nighthawk (Chordeiles minor)

Antillean Nighthawk (Chordeiles gundlachii)

Short-tailed Nighthawk (Lurocalis semitorquatus)

“Short-tailed Nighthawk” (L. s. semitorquatus)

“Natterer’s Nighthawk” (L. s. nattereri)

Rufous-bellied Nighthawk (Lurocalis rufiventris)

Band-tailed Nighthawk (Nyctiprogne leucopyga)

Bahian Nighthawk (Nyctiprogne vielliardi)

Blackish Nightjar (Nyctipolus nigrescens)

Pygmy Nightjar (Nyctipolus hirundinaceus)

Common Pauraque (Nyctidromus albicollis)

Anthony’s Nightjar (Nyctidromus anthonyi)

Todd’s Nightjar (Setopagis heterura)

Little Nightjar (Setopagis parvula)

Roraiman Nightjar (Setopagis whitelyi)

Cayenne Nightjar (Setopagis maculosa)

Sickle-winged Nightjar (Eleothreptus anomalus)

White-winged Nightjar (Eleothreptus candicans)

Band-winged Nightjar (Systellura longirostris)

“Rufous-necked Nightjar” (S. l. uficervix)

“Tepui Nightjar” (S. l. roraimae)

“Band-winged Nightjar” (S. l. longirostris)

“Mocha Nightjar” (S. l. mochaensis)

Tschudi’s Nightjar (Systellura decussata)

Swallow-tailed Nightjar (Uropsalis segmentata)

Lyre-tailed Nightjar (Uropsalis lyra)

White-tailed Nightjar (Hydropsalis cayennensis)

Spot-tailed Nightjar (Hydropsalis maculicaudus)

Ladder-tailed Nightjar (Hydropsalis climacocerca)

Scissor-tailed Nightjar (Hydropsalis torquata)

Long-trained Nightjar (Macropsalis forcipata)

Jamaican Pauraque (Siphonorhis americana) †

Least Pauraque (Siphonorhis brewsteri)

Chocó Poorwill (Nyctiphrynus rosenbergi)

Eared Poorwill (Nyctiphrynus mcleodii)

Yucatán Poorwill (Nyctiphrynus yucatanicus)

Ocellated Poorwill (Nyctiphrynus ocellatus)

Common Poorwill (Phalaenoptilus nuttallii)

Chuck-will’s-widow (Antrostomus carolinensis)

Rufous Nightjar (Antrostomus rufus)

“Northern Rufous Nightjar” (A. r. minimus)

“St. Lucia Nightjar” (A. r. otiosus)

“Southern Rufous Nightjar” (A. r. rufus)

Cuban Nightjar (Antrostomus cubanensis)

Hispaniolan Nightjar (Antrostomus ekmani)

Tawny-collared Nightjar (Antrostomus salvini)

Yucatán Nightjar (Antrostomus badius)

Silky-tailed Nightjar (Antrostomus sericocaudatus)

Buff-collared Nightjar (Antrostomus ridgwayi)

Eastern Whip-poor-will (Antrostomus vociferus)

Mexican Whip-poor-will (Antrostomus arizonae)

Puerto Rican Nightjar (Antrostomus noctitherus)

Dusky Nightjar (Antrostomus saturatus)

Brown Nightjar (Veles binotatus)

Red-necked Nightjar (Caprimulgus ruficollis)

Jungle Nightjar (Caprimulgus indicus)

Gray Nightjar (Caprimulgus jotaka)

Palau Nightjar (Caprimulgus phalaena)

European Nightjar (Caprimulgus europaeus)

Sombre Nightjar (Caprimulgus fraenatus)

Rufous-cheeked Nightjar (Caprimulgus rufigena)

Egyptian Nightjar (Caprimulgus aegyptius)

Sykes’s Nightjar (Caprimulgus mahrattensis)

Vaurie’s Nightjar (Caprimulgus centralasicus)

Nubian Nightjar (Caprimulgus nubicus)

“Nubian Nightjar” (C. n. nubicus)

“Torrid Nightjar” (C. n. torridus)

“Socotra Nightjar” (C. n. jonesi)

Golden Nightjar (Caprimulgus eximius)

Jerdon’s Nightjar (Caprimulgus atripennis)

Large-tailed Nightjar (Caprimulgus macrurus)

Mees’s Nightjar (Caprimulgus meesi)

Andaman Nightjar (Caprimulgus andamanicus)

Philippine Nightjar (Caprimulgus manillensis)

Sulawesi Nightjar (Caprimulgus celebensis)

Donaldson-Smith’s Nightjar (Caprimulgus donaldsoni)

Black-shouldered Nightjar (Caprimulgus nigriscapularis)

Fiery-necked Nightjar (Caprimulgus pectoralis)

Montane Nightjar (Caprimulgus poliocephalus)

“Montane Nightjar” (C. p. poliocephalus)

“Ruwenzori’s Nightjar” (C. p. ruwenzorii)

Indian Nightjar (Caprimulgus asiaticus)

Madagascan Nightjar (Caprimulgus madagascariensis)

Swamp Nightjar (Caprimulgus natalensis)

Nechisar Nightjar (Caprimulgus solala)

Plain Nightjar (Caprimulgus inornatus)

Star-spotted Nightjar (Caprimulgus stellatus)

Savannah Nightjar (Caprimulgus affinis)

Freckled Nightjar (Caprimulgus tristigma)

Bonaparte’s Nightjar (Caprimulgus concretus)

Salvadori’s Nightjar (Caprimulgus pulchellus)

Prigogine’s Nightjar (Caprimulgus prigoginei)

Bates’s Nightjar (Caprimulgus batesi)

Long-tailed Nightjar (Caprimulgus climacurus)

Slender-tailed Nightjar (Caprimulgus clarus)

Square-tailed Nightjar (Caprimulgus fossii)

Standard-winged Nightjar (Caprimulgus longipennis)

Pennant-winged Nightjar (Caprimulgus vexillarius)

References

Cleere, N., and D. Nurney. 1998. Nightjars: A Guide to Nightjars and Related Nightbirds. Pica Press, Sussex.

Holyoak, D.T. 2001. Nightjars and Their Allies. Oxford University Press.

Hume, J.P. 2017. Extinct Birds (Second Edition). Bloomsbury Publishing PLC, London.

Roberson, D. 2000. Bird Families of the World: Nightjars & Allies, Caprimulgidae, http://creagrus.home.montereybay.com/nightjars.html. (Posted February 5, 2000. Accessed November 3, 2019.)