Overview
The white-throated nightjar or white-throated eared-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.
Taxonomy
The white-throated nightjar was formally known as Eurostopodus 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. However, later research separated the three into their own species based on differences in vocalizations and morphology. Since then, E. mystacalis has remained monotypic.
Etymology
The genus name, Eurostopodus is derived from the Greek words meaning 'strong' and or meaning 'foot', while the species name mystacalis is derived from Latin and means 'moustache'.
Description
E. mystacalis is the largest Australian nightjar species and measures around 30–37 cm. The beak is greyish black and the legs are dark brown and short making travel on ground difficult for this bird. 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.
Distribution and habitat
The white-throated nightjar is a species endemic to eastern Australia. 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. 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. Many individuals have been found to specifically live in woodlands that have experienced disturbances such as forest fires.
Vocalisations
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 containing 9-12 notes and lasting for three to six seconds. Adults communicate to their young using low husky notes. In response, chicks make harsh 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.
Diet
This species is an aerial hunter that comes out to forage primarily at night. They employ hawking and target a wide variety of flying insects. Its diet includes mantises, crickets and grasshoppers, beetles, and winged ants, although large moths make up the bulk of its diet. 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.
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. Both sexes are involved in parenting and take turns incubating the egg. 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. 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.
Conservation
Although E. mystacalis is currently listed as least concern, the trend in their overall population is decreasing. 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. The current estimate of individuals is unknown.