The silky-tailed nightjar (''Antrostomus sericocaudatus'') is a species of

nightjar Nightjars are medium-sized nocturnal or crepuscular birds in the family Caprimulgidae and order Caprimulgiformes, characterised by long wings, short legs, and very short bills. They are sometimes called bugeaters, their primary source of food ...

birds in the family Caprimulgidae. It is found in

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

, and

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

. Its natural

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

is subtropical or tropical moist lowland

forest A forest is an ecosystem characterized by a dense ecological community, community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, ...

Taxonomy and systematics

The silky-tailed nightjar has two subspecies, the nominate ''Antrostomus sericocaudatus sericocaudatus'' and ''A. s. mengeli''. At one time the tawny-collared nightjar (''A. salvini'') and Yucatan nightjar (''A. badius'') were also treated as subspecies of it.Schulenberg, T. S., M. d. C. Arizmendi, C. I. Rodríguez-Flores, C. A. Soberanes-González, R. A. Behrstock, and A. Van Tatenhove (2020). Yucatan Nightjar (''Antrostomus badius''), version 1.0. In Birds of the World (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, retrieved October 16, 2021

Description

The adult male silky-tailed nightjar has light grey-brown, vermiculated plumage with a strong blackish streak on the top of the head and the nape. It has blackish facial bristles and blackish spots with rufous on the side. Its hind-neck has narrow rufous-tawny half-collar plumage. The mantle, back, rump, and upper tail of a silky-tailed nightjar converts to blackish-brown with irregular patterns of buff and cinnamon. The breast is blackish-brown with short narrow bars of cinnamon and the belly is blackish-brown with blotches and irregular narrow bars of buff.

Distribution and Habitat

The nominate subspecies of silky-tailed nightjar is found in the Atlantic Forest region of southeastern Brazil, eastern Paraguay, and extreme northeastern Argentina (

Misiones Province Misiones (, ''Missions'') is one of the Provinces of Argentina, 23 provinces of Argentina, located in the northeastern corner of the country in the Mesopotamia, Argentina, Mesopotamia region. It is surrounded by Paraguay to the northwest, Brazil ...

). It inhabits the interior and edges of

secondary forest A secondary forest (or second-growth forest) is a forest or woodland area which has regenerated through largely natural processes after human-caused Disturbance (ecology), disturbances, such as Logging, timber harvest or agriculture clearing, or ...

and subtropical evergreen forest. In elevation it ranges between . ''A. s. mengeli'' is found in eastern Peru, northwestern Bolivia, and in scattered sites in Brazil's

Pará Pará () is a Federative units of Brazil, state of Brazil, located in northern Brazil and traversed by the lower Amazon River. It borders the Brazilian states of Amapá, Maranhão, Tocantins (state), Tocantins, Mato Grosso, Amazonas (Brazilian st ...

state. It inhabits a variety of landscapes including mature tropical forest, '' terra firme'' forest, and lowland

tropical rainforest Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes (in the torrid zo ...

. In elevation it ranges between .Wilkinson, F. A. W. (2020). Silky-tailed Nightjar (''Antrostomus sericocaudatus''), version 1.0. In Birds of the World (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY. retrieved October 16, 2021

Diet

Nightjars eat a variety of insects and the young are fed by their parents via regurgitation. Regurgitation is used by birds where it is to bring already swallowed food back up through one's throat and out the mouth to feed their young. The nestlings also forage for ground insects around the nest-site or pick up small soil granules to aid in digestion.

Breeding and Behavior

The breeding period of the silky-tailed nightjar spans from August to December, which coincides with half of the dry season through the beginning of the rainy season. The courtship begins in mid-August and nests are made between early September and mid-November. They are heard vocalizing throughout the year, primarily at dawn and dusk; vocal activity increased in August and peaked in September and October, and declined in November. When the courtship begins, male nightjars will emit the usual song slightly faster. The female will fly in and perch on a nearly horizontal branch about 10 meters away. When the male sees the female, it will suddenly half the interval between notes, uttering several notes in quick succession. As the male flies to the female, he will open his tail like a fan, lower his wings against the branch and mount the female. Adult nightjars have been observed to share incubation duties with the female partner attending the nest throughout the day and the male at night. As their anti-predator behavior, injury-feigning is commonly observed during the nesting stage. Injury-feigning is a behavior that aims to fool predators and lure them away from a nest by pretending to be injured to distract the attention of the predator. Adult nightjars readily flush, which is a distraction ploy to draw the predator's attention on the adult, when approached. After flushing, adults reposition themselves, facing the same way and parallel to the trail, which provides them a larger open area to escape from potential predators. When these behaviors are observed, adults are highly obscure while the eggs are visible.

Vocalization

The two subspecies of silky-tailed nightjar have significantly different songs. That of ''A. s. sericocaudatus'' is "a short tonal gliss connecting the two major pitch peaks ''ree-o-ree''." That of ''A. s. mengeli'' "has an almost mournful, undulating ''doh wheo eeo''." Both members of a mated pair sing, usually from a low perch or during low flight, and mostly at dawn and dusk.

Status

The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

has assessed the silky-tailed nightjar as being of Least Concern, though it population is unknown and believed to be decreasing. No immediate threats have been identified. Because "the Atlantic Forest and the Amazon Basin reconstantly threatened with human development...known populations of the Silky-tailed Nightjar may rapidly decline."

References

{{Taxonbar, from=Q1260867 Antrostomus Birds of South America Birds described in 1849 Taxa named by John Cassin Taxonomy articles created by Polbot