White-throated nightjar

The white-throated nightjar (Eurostopodus mystacalis) is a species of nightjar in the family Caprimulgidae. It is endemic to eastern Australia; it is a non-breeding winter visitor in Papua New Guinea. Its natural habitat is subtropical or tropical dry forests.

White-throated nightjar
Kobble Creek, SE Queensland, Australia
Roadkill, Kobble Creek, SE Queensland, Australia
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Caprimulgiformes
Family: Caprimulgidae
Genus: Eurostopodus
Species:
E. mystacalis
Binomial name
Eurostopodus mystacalis
(Temminck, 1826)
Synonyms

White-throated Goat-sucker, White-throated eared nightjar

Taxonomy

The white-throated nightjar was formally known as Eurstopodus albogularis but was later reclassified to E. mystacalis. Some texts may still refer to this species as Eurostopodus mystacalis albogularis. This species was regarded as a subspecies and conspecific with ''Eurostopodus exul'' and ''Eurostopodus nigripennis''.[2] However, later research separated the three into their own species based on differences in vocalizations and morphology. Since then, E. mystacalis has remained monotypic. [3]

Etymology

The genus name, Eurostopodus is derived from the Greek words eurostos meaning strong and podos or pous meaning foot. While the species name, mystacalis is derived from Latin and means moustache.[4]

Description
Drawing of white-throated nightjar

E. mystacalis is the largest Australian nightjar species and measures around 30-37 cm.[5][6] Males and females are very similar in appearance and display a dark variegated body. The upper body and wings are greyish-brown with broad blackish-brown streaks and spots. The underbody is spotted brown or greyish white and barred rufous. The upper part of the wing is greyish-white but speckled brownish-black as well. Its neck is buff colored with a large white patch on either side of its throat making it appear as if it’s wearing a collar. The four outermost primaries have a distinct white spot that help to differentiate it from similar looking nightjars.[5]Its tail is brown with black speckles and absent of any white.[3] The beak is greyish black and the legs are dark brown and short making travel on ground difficult for this bird.[3][7]


When in flight, the wings are long, pointed and held above its head. This species bounces buoyantly while flying and takes frequent glides accompanied by a double wing beat.[5]

Distribution and Habitat

The white-throated nightjar is a species endemic to eastern Australia.[3] Birds reside in northeast Australia throughout the year and travel to the south to breed. Specifically, their breeding range is in Australia east of the Great Dividing Range, New Caledonia, or the Solomon Islands.[8] Birds are most abundantly found in New South Wales and Queensland. During the winter, birds migrate from February until April to Papua New Guinea as non-breeding visitors.[9] Although most overwinter outside of Australia, there are birds that remain in north and central Queensland all year long.

This species is able inhabit a wide variety of habitats but is most commonly found in dry low-elevation forests. They prefer to nest and roost in dry sclerophyll woodlands with sparse and discontinuous understory.[10][11] Many individuals have been found to specifically live in woodlands that have experienced disturbances such as forest fires.[11] In New South Wales, birds have been found inhabiting the edges of rainforests and mangroves.[8] Those that winter in New Guinea occur in savannas, open grasslands, forest edges, marshlands and gardens. Wintering birds may also be found along the beaches of the Solomon islands.[12]

Behaviour

Vocalizations

White-throated nightjars are often heard more than seen. They have a distinct song that help distinguish it from species it was previously conspecific to. Mostly made by males, their song is composed of a series of rapidly ascending bubbling notes. Their song is described as “wow-wow-wow-wow-ho-ho ho-ho-o-o-O” containing 9-12 notes and lasts for 3-6 seconds.[3][5] It puffs out its throat-patch while singing.[3] Females can occasionally also sing. This song is mostly heard during dawn or dusk and subsides once the breeding season is over.[5]

Their call is also very distinct described as an ascending "whook whook whook" for about 10 notes which then accelerates into a 'cackle of laughter'.[6][7]

Adults communicate to their young using low husky notes. In response, chicks make harsh “khaah” notes but will cheep when asking for food. If chicks or the nest is threatened, parents can make distracting barks, tocks and hisses. During courtship, both females and males make low croaks and bill snaps to each other.[5]

Diet

This species is a aerial hunting that comes out to forage primarily at night. They employ hawking and target a wide variety of flying insects. Its diet includes mantids, crickets and grasshoppers, beetles, and winged ants, although large moths make up the bulk of its diet.[4] It may form foraging groups of 20 or more individuals especially when on migrations. When migrating, birds travel during the day so they can maximize their time hunting at night.[8]

Reproduction

Breeding season occurs from September to February but differs slightly depending on the region. For birds in southern Australia it is mainly from October-December. The Solomon Islands is October-November and New Caledonia is August-September. Courtship involves males chasing females, displays from the males, and vocal exchanges between both sexes. Males will often land on low branches and wave its wings up and down while calling.[5]

White-throated nightjars do not make nests and instead lay their eggs directly onto leaf litter or bare soil. The eggs are pale yellow with purplish-brown splotches and clutch size is one. Their preferred nesting sites are on hilltops or stony ridges and they often reuse the same nesting sites every year.[13] Both sexes are involved in parenting and take turns incubating the egg.[5] During the day, the female will incubate the egg while the males nests nearby. Then at night, the male will take over incubation, allowing the female to hunt for food. If the nest or nestling are threatened, parents put on a variety of distractions that include short flights, vocal hisses and barks, and flicking tail movements while on the ground. Incubation lasts from 29 to 33 days and newly hatched chicks are precocial. Chicks are quite capable and are mobile starting on the first day.[7] After approximately 30 days, the chick fledges. Three weeks after the first egg hatches, females may lay another egg. If an egg is lost females will lay another egg to replace it and can lay up to 5 eggs per breeding season.[3]

Conservation

Although E. mystacalis is currently listed as least concern, the trend in their overall population is decreasing.[14] They are often traveling along the sides of roads at night searching for food resulting in fatal traffic collisions. Feral cats and dogs prey upon both adults and chicks. Fire ants (Wasmannia auropunctata) introduced in the 1970s have spread into E. mystacalis native range and threaten nestlings. Furthermore, increasing bushfires have affected large parts of the Melaleuca savanna, destroying habitable sites.[2] The current estimate of individuals is unknown.[14]


References
  1. BirdLife International (2017). "Eurostopodus mystacalis". The IUCN Red List of Threatened Species. IUCN. 2017: e.T22725660A112390311. doi:10.2305/IUCN.UK.2017-1.RLTS.T22725660A112390311.en. Retrieved 15 January 2018.
  2. M.M. Ekstrom, Johnathan; P.G. Jones, Julia; Willis, Jake; Tobias, Joe; Dutson, Guy; Barre, Nicolas (2002). "New information on the distribution, status and conservation of terrestrial bird species in Grande Terre, New Caledonia". Emu - Austral Ornithology. 2 (102): 197:207. doi:10.1071/MU01004. Retrieved 10 October 2020.
  3. Cleere, N; G. M., Kirwan; E.F.J, Garcia (2020). "White-throated Nightjar(Eurostopodus mystacalis)". In Birds of the World. 1. doi:10.2173/bow.whtnig3.01. Retrieved 14 October 2020.
  4. Cayley, Neville William; Chisholm, Alec H. (1971). What Bird Is That?: A Guide to the Birds of Australia (6 ed.). Sydney: Angus and Robertson. p. 82. ISBN 0207941300. Retrieved 11 October 2020.
  5. Cleere, Nigel (1998). Nightjars: a guide to nightjars and related nightbirds. Pica Press. pp. 180–181. ISBN 9781408135464. Retrieved 14 October 2020.
  6. "White-throated nightjar". Queensland Government. Department of Environment and Science. Retrieved 11 October 2020.
  7. Hollands, David (1991). Birds of the night: owls, frogmouths, and nightjars of Australia. Balgowlah N.S.W: Reed. pp. 176–179. ISBN 0730103250. Retrieved 11 October 2020.
  8. Roderick, Michael; Filewood, Winston (2012). "Observation of White-throated Nightjars at Tahlee, New South Wales" (PDF). The Whistler. 6: 59–60. Retrieved 12 October 2020.
  9. Beehler, Bruce M.; Pratt, Thane K. (2016). Bird of New Guinea. Princeton: Princeton University Press. p. 151. ISBN 9781400880713. Retrieved 14 October 2020.
  10. Kavanagh, Rodney P.; Bamkin, Khia L. (1995). "Distribution of nocturnal forest birds and mammals in relation to the logging mosaic in south-eastern New South Wales, Australia". Biological Conservation. 71 (1): 41–53. doi:10.1016/0006-3207(94)00019-M.
  11. Kavanagh, Rp; Debus, S; Tweedie, T; Webster, R (1995). "Distribution of Nocturnal Forest Birds and Mammals in North-Eastern New South Wales: Relationships With Environmental Variables and Management History". Wildlife Research. 22 (3): 359. doi:10.1071/WR9950359. ISSN 1035-3712.
  12. Read, John L.; Moseby, Katherine (2006). "Vertebrates of Tetepare Island, Solomon Islands" (PDF). Pacific Science. 60 (1): 69–79. doi:10.1353/psc.2005.0060. ISSN 1534-6188.
  13. Elliott, A. J. (1935). "Notes on the White-throated Nightjar". Emu - Austral Ornithology. 35 (2): 129–132. doi:10.1071/MU935129. ISSN 0158-4197.
  14. BirdLife International. "Eurostopodus mystacalis (amended version of 2016 assessment)". he IUCN Red List of Threatened Species. Retrieved 14 October 2020.
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