Owlet-nightjar

Owlet-nightjars Temporal range: Early Miocene to present
Barred owlet-nightjar (Aegotheles bennettii)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Clade:	Strisores
Clade:	Daedalornithes
Order:	Aegotheliformes Worthy et al., 2007
Family:	Aegothelidae Bonaparte, 1853
Genus:	Aegotheles Vigors & Horsfield, 1827
Type species
Caprimulgus novaehollandiae [1] Latham, 1790
Synonyms
EuaegothelesMathews, 1918 MegaegothelesScarlett, 1968

Owlet-nightjars are small crepuscular birds related to the nightjars and frogmouths. Most are native to New Guinea, but some species extend to Australia, the Moluccas, and New Caledonia. A flightless species from New Zealand is extinct. There is a single monotypic family Aegothelidae with the genus Aegotheles.

Owlet-nightjars are insectivores which hunt mostly in the air but sometimes on the ground; their soft plumage is a cryptic mixture of browns and paler shades, they have fairly small, weak feet (but larger and stronger than those of a frogmouth or a nightjar), a tiny bill that opens extraordinarily wide, surrounded by prominent whiskers. The wings are short, with 10 primaries and about 11 secondaries; the tail long and rounded.

Taxonomy

The genus Aegotheles was introduced in 1827 by the naturalists Nicholas Vigors and Thomas Horsfield to accommodate a single species, Caprimulgus novaehollandiae Latham, 1790. ^{[2] [3]} This binomial name is considered to be a junior synonym of Caprimulgus cristatus, the Australian owlet-nightjar that was introduced by George Shaw earlier in 1790. ^{[4] [5] [6]} The genus name means "nightjar" or "goatsucker" from Ancient Greek αιξ/aix, αιγος/aigos meaning "goat" and θηλαζω/thēlazō meaning "to suckle". ^[7] The family Aegothelidae was introduced (as subfamily Aegothelinae within the family Caprimulgidae) in 1853 by the French naturalist Charles Lucien Bonaparte. ^{[8] [9]}

A comprehensive 2003 study analyzing mtDNA sequences of Cytochrome b and ATPase subunit 8 suggests that 12 living species of owlet-nightjar should be recognized, as well as another that became extinct early in the second millennium AD. ^[10]

The relationship between the owlet-nightjars and the (traditional) Caprimulgiformes has long been controversial and obscure and remains so today: in the 19th century they were regarded as a subfamily of the frogmouths, and they are still generally considered to be related to the frogmouths and/or the nightjars. It appears though that they are not as closely related to either as previously thought, and that the owlet-nightjars share a more recent common ancestor with the Apodiformes. ^[11] As has been suggested on occasion since morphological studies of the cranium in the 1960s, ^[12] they are thus considered a distinct order, Aegotheliformes. This, the caprimulgiform lineage(s), and the Apodiformes, are postulated to form a clade called Cypselomorphae, with the owlet-nightjars and the Apodiformes forming the clade Daedalornithes.

In form and habits, however, they are very similar to both caprimulgiform group – or, at first glance, to small owls with huge eyes. The ancestors of the swifts and hummingbirds, two groups of birds which are morphologically very specialized, seem to have looked very similar to a small owlet-nightjar, possessing strong legs and a wide gape, while the legs and feet are very reduced in today's swifts and hummingbirds, and the bill is narrow in the latter.

Owlet-nightjars are an exclusively Australasian group, but close relatives apparently thrived all over Eurasia in the late Paleogene.

Molecular phylogenetic studies have shown the Aegotheliformes are sister to the Apodiformes containing the hummingbirds, swifts and treeswifts. ^{[13] [14]} The two orders shared a common ancestor around 57 million years ago. ^[14]

Strisores	Caprimulgiformes Caprimulgidae (nightjars) Steatornithiformes Steatornithidae (oilbird) Nyctibiiformes Nyctibiidae (potoos) Podargiformes Podargidae (frogmouths) Aegotheliformes Aegothelidae (owlet-nightjars) Apodiformes Trochilidae (hummingbirds) Apodidae (swifts) Hemiprocnidae (treeswifts)

The following cladogram is based on a 2003 molecular phylogenetic study that sampled three regions of mitochondrial DNA mainly extracted from museum specimens. Some of the nodes were not well supported by the data. ^[10]

Aegotheles

New Caledonian owlet-nightjar, Aegotheles savesi Feline owlet-nightjar, Aegotheles insignis Starry owlet-nightjar, Aegotheles tatei Moluccan owlet-nightjar, Aegotheles crinifrons Australian owlet-nightjar, Aegotheles cristatus Barred owlet-nightjar, Aegotheles bennettii Vogelkop owlet-nightjar, Aegotheles affinis Karimui owlet-nightjar, Aegotheles terborghi Wallace's owlet-nightjar, Aegotheles wallacii Mountain owlet-nightjar, Aegotheles albertisi

Species

The genus contains ten species: ^[15]

• Feline owlet-nightjar, Aegotheles insignis – montane New Guinea
• Starry owlet-nightjar, Aegotheles tatei – Fly/Elevala area of central east New Guinea and Amazon Bay area of far southeast New Guinea
• Moluccan owlet-nightjar, Aegotheles crinifrons – Halmahera and Bacan Islands (north Moluccas)
• Wallace's owlet-nightjar, Aegotheles wallacii – Waigeo (Raja Ampat Islands, northwest of New Guinea), Aru Islands (southwest of New Guinea), Bird's Head Peninsula (northwest New Guinea) and patchily in New Guinea
• Mountain owlet-nightjar, Aegotheles albertisi – montane New Guinea
• New Caledonian owlet-nightjar, Aegotheles savesi – Grande Terre (New Caledonia); likely extinct
• Barred owlet-nightjar, Aegotheles bennettii – central to southeast New Guinea
• Vogelkop owlet-nightjar, Aegotheles affinis –Arfak Mountains, Bird's Head Peninsula (northwest New Guinea)
• Karimui owlet-nightjar, Aegotheles terborghi – Karimui Basin (central south New Guinea)
• Australian owlet-nightjar, Aegotheles cristatus – central south, southeast New Guinea, Australia and Tasmania

A fossil proximal right tarsometatarsus (MNZ S42800) was found at the Bannockburn Formation of the Manuherikia Group near the Manuherikia River in Otago, New Zealand. Dating from the Early to Middle Miocene (Altonian, 19–16 million years ago), it seems to represent an owlet-nightjar ancestral to A. novaezealandiae. ^[16] In 2022, an additional specimen from the same locality was described by Worthy et al. as a new extinct species of Aeotheles, A. zealandivetus. The holotype specimen is NMNZ S.52917, a distal right tarsometatarsus. ^[17]

References

1. "Apodidae". aviansystematics.org. The Trust for Avian Systematics. Retrieved 2023-08-05.
2. Vigors, Nicholas Aylward; Horsfield, Thomas (1826). "Australian birds in the collection of the Linnean Society; with an attempt at arranging them according to their natural affinities". Transactions of the Linnean Society of London (in English and Latin). 15 (1) (published 1827): 170-334 [194]. For the publication date see: Raphael, Sandra (1970). "The publication dates of the Transactions of the Linnean Society of London, Series I,1791–1875". Biological Journal of the Linnean Society. 2 (1): 61–76. doi:10.1111/j.1095-8312.1970.tb01688.x.
3. Latham, John (1790). Index Ornithologicus, Sive Systema Ornithologiae: Complectens Avium Divisionem In Classes, Ordines, Genera, Species, Ipsarumque Varietates (in Latin). Vol. 2. London: Leigh & Sotheby. p. 588.
4. Shaw, George (1790). White, John (ed.). Journal of a Voyage to New South Wales : with sixty-five plates of nondescript animals, birds, lizards, serpents, curious cones of trees and other natural productions. London: Printed for J. Debrett. p. 241 Supp. For Shaw as author of the specific name see: Sherborn, C. Davies (1891). "Note on the authors of the specific names in John White's 'Journal of a Voyage to New South Wales', 1790". The Annals and Magazine of Natural History including Zoology, Botany, and Geology. 6th series. 7: 535. doi:10.1080/00222939109460662.
5. Hemming, Francis, ed. (1956). "Report by the Secretary on the relative dates of publication of the names Caprimulgus novaehollandiae Latham and Caprimulgus cristatus Shaw in White, both currently treated as having been published in 1790". Opinions and Declarations Rendered by the International Commission on Zoological Nomenclature. Vol. 1 Section D Part D.4. London: International Trust for Zoological Nomenclature. pp. 204–206.
6. Peters, James Lee, ed. (1940). Check-List of Birds of the World. Vol. 4. Cambridge, Massachusetts: Harvard University Press. p. 181.
7. Jobling, James A. "Aegotheles". The Key to Scientific Names. Cornell Lab of Ornithology. Retrieved 7 October 2025.
8. Bock, Walter J. (1994). History and Nomenclature of Avian Family-Group Names. Bulletin of the American Museum of Natural History. Vol. 222. New York: American Museum of Natural History. pp. 142, 229.
9. Bonaparte, Charles Lucien (1853). "Classification ornithologique par series". Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences (in French). 37: 641–647 [645].
10. Dumbacher, J.P.; Pratt, T.K.; Fleischer, R.C. (2003). "Phylogeny of the owlet-nightjars (Aves: Aegothelidae) based on mitochondrial DNA sequence". Molecular Phylogenetics and Evolution. 29 (3): 540–549. doi:10.1016/S1055-7903(03)00135-0.
11. Mayr (2002)
12. Simonetta (1967)
13. Prum, Richard O.; Berv, Jacob S.; Dornberg, Alex; Field, Daniel J.; Townsend, Jeffrey P.; Lemmon, Emily Moriarty; Lemmon, Alan R. (2015). "A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing". Nature. 526 (7574): 569–573. Bibcode:2015Natur.526..569P. doi:10.1038/nature15697. PMID   26444237. S2CID   205246158.
14. Stiller, J.; et al. (2024). "Complexity of avian evolution revealed by family-level genomes". Nature. 629 (8013): 851–860. Bibcode:2024Natur.629..851S. doi: 10.1038/s41586-024-07323-1 . PMC   11111414 . PMID   38560995.
15. Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (February 2025). "Owlet-nightjars, treeswifts, swifts". IOC World Bird List Version 15.1. International Ornithologists' Union. Retrieved 9 October 2025.
16. Worthy et al. (2007)
17. Worthy, Trevor H.; Scofield, R. Paul; Salisbury, Steven W.; Hand, Suzanne J.; De Pietri, Vanesa L.; Archer, Michael (2022-04-05). "Two new neoavian taxa with contrasting palaeobiogeographical implications from the early Miocene St Bathans Fauna, New Zealand". Journal of Ornithology. 163 (3): 643–658. doi: 10.1007/s10336-022-01981-6 . hdl: 1959.4/unsworks_79974 . ISSN   2193-7206. S2CID   247993690.

Sources

• Mayr, Gerald (2002): Osteological evidence for paraphyly of the avian order Caprimulgiformes (nightjars and allies). J. Ornithol. 143(1): 82–97. doi:10.1007/BF02465461 PDF fulltext
• Simonetta, A.M. (1967): Cinesi e morfologia del cranio negli Uccelli non passeriformi. Studio su varie tendenze evolutive. Part II – Striges, Caprimulgiformes ed Apodiformes ["Cranial kinesis and morphology of non-passerine birds. Study of various evolutionary tendencies. Part II – Striges, Caprimulgiformes and Apodiformes"]. [In Italian^{[ verification needed ]}] Archivio Zoologico Italiano52: 1–35.
• Worthy, Trevor H.; Tennyson, A.J.D.; Jones, C.; McNamara, J.A. & Douglas, B.J. (2007): Miocene waterfowl and other birds from central Otago, New Zealand. J. Syst. Palaeontol. 5(1): 1–39. doi:10.1017/S1477201906001957 (HTML abstract)