Introduction
The Silky-tailed Nightjar (Antrostomus sericocaudatus) is a poorly known South American nightjar in the family Caprimulgidae. It is a resident species associated with humid forests, but its distribution is divided between the Atlantic Forest of southeastern South America and scattered forests of the Amazon Basin. Its nocturnal habits, cryptic plumage and low population density make it difficult to locate by sight, although its distinctive song can reveal its presence.
Physical Description
The Silky-tailed Nightjar is a medium-sized nightjar measuring approximately 27–30 centimetres in length. Its plumage is predominantly dark brown, greyish-brown and buff, with fine spotting and barring that provide effective camouflage among leaf litter, branches and shaded vegetation. A narrow buff or ochre collar is usually visible across the nape, while the throat, breast, belly and flanks are marked with pale spots and bars.
The tail is rounded and gives the species its common name. Adult males have conspicuous white tips or outer tail markings, whereas females show similar markings in buff or rufous tones. The sexes are otherwise alike, although males may be slightly larger. Juveniles are generally paler and less strongly marked than adults.
Range and Habitat
The species has a disjunct distribution in South America. The nominate subspecies, A. s. sericocaudatus, occurs in the Atlantic Forest of southeastern Brazil, eastern Paraguay and Misiones Province in northeastern Argentina. The subspecies A. s. mengeli occurs in parts of eastern Peru, northwestern Bolivia and scattered areas of Amazonian Brazil.
It is primarily associated with humid lowland and foothill forest, including mature rainforest, Atlantic Forest, forest margins, dense understorey and areas with bamboo or other thick vegetation. Records from the Amazon Basin are widely scattered, while the Atlantic Forest population is concentrated in a region that has experienced extensive habitat loss and fragmentation.
The Silky-tailed Nightjar is considered resident rather than migratory. Local movements may occur, but long-distance migration has not been established.
Where to See This Species
The Silky-tailed Nightjar is difficult to see, and most encounters involve a bird heard calling from forest edge, dense understorey or a low perch. Nocturnal surveys should be conducted responsibly and with local permission where required.
Parque Provincial Cruce Caballero, Misiones, Argentina
This protected Atlantic Forest site is a documented locality for the species, including records of nests of the nominate subspecies. Forest interior, dense understorey and quiet forest roads may be suitable places to listen for calling birds, particularly during the breeding season from late winter into spring. Access conditions and visitor arrangements should be confirmed locally before travelling.
Nearby accommodation: The nearby settlement of Cruce Caballero provides the closest basic accommodation options, while San Pedro offers a broader choice of guest houses, hotels and self-catering accommodation.
Parque Nacional Baritú, Salta, Argentina
The Silky-tailed Nightjar is documented in the park’s biodiversity records. The protected Yungas forest provides suitable habitat, although the species is likely to be encountered only rarely and usually through its song. Forest-edge and lowland forest areas are the most appropriate places to listen during the hours around dusk and dawn.
Nearby accommodation: Los Toldos is the practical gateway settlement, with simple guesthouses and camping options. Orán provides a wider selection of hotels and other accommodation for visitors travelling through the region.
Behaviour and Diet
The Silky-tailed Nightjar is mainly crepuscular and nocturnal. It commonly becomes active around dusk, during the first part of the night and again before dawn. It forages by making short aerial sallies from low perches, taking moths, beetles and other flying insects in flight. Its broad gape and sensitive bristles around the mouth are adaptations associated with aerial insect hunting.
During daylight, the bird usually remains motionless on a branch, the ground or among leaf litter. Its cryptic plumage makes it difficult to detect, and a disturbed bird may rely on stillness or a distraction display rather than flying far from the nest.
Breeding information is limited but has been documented in the Atlantic Forest. The species lays its eggs directly on the ground without constructing a substantial nest. The usual clutch is two pale or white eggs placed among leaves or low vegetation. Both adults may participate in incubation, and adults can use distraction behaviour to draw predators away from eggs or young.
The songs of the two recognised subspecies differ. The Atlantic Forest form has a short, tonal, rising and falling phrase, while the Amazonian form has been described as a more mournful, undulating series of notes. Vocal activity is especially useful for locating the species because visual encounters are uncommon.
Identification Tips
- Look for a large, dark nightjar with long wings, a rounded tail and strongly mottled brown-and-buff plumage.
- A narrow buff collar on the nape can be visible at close range.
- Adult males show white outer tail tips or markings; females show corresponding buff or rufous markings.
- The species is usually found in forest interior, forest edge or dense understorey rather than open grassland.
- Listen for the distinctive, repeated song at dusk, during the early night or before dawn.
- The Rufous Nightjar (Antrostomus rufus) can occur in parts of the same broad region. The Silky-tailed Nightjar is generally darker, has different tail markings and is best separated by its distinctive voice and habitat context.
Conservation Status
The Silky-tailed Nightjar is currently assessed as Least Concern on the IUCN Red List. Its total population size has not been reliably quantified, and the species is not frequently encountered across much of its range.
The principal conservation concern is the continuing loss and fragmentation of humid forest in the Atlantic Forest and Amazon Basin. Logging, agricultural expansion, infrastructure development and other forms of land conversion can reduce suitable habitat. Because the species is poorly studied and locally scarce, further field surveys and monitoring are important for clarifying its population trend, habitat requirements and regional conservation status.
Maintaining large, connected forest reserves, protecting remaining Atlantic Forest and Amazonian habitats, and managing forest edges and understorey responsibly are likely to benefit the species. Research on its vocalisations, breeding biology and distribution can also improve the accuracy of future assessments.
Frequently Asked Questions
Where does the Silky-tailed Nightjar live?
It occurs in two widely separated South American regions: the Atlantic Forest of southeastern Brazil, eastern Paraguay and northeastern Argentina, and scattered humid forests in eastern Peru, northwestern Bolivia and Amazonian Brazil.
Is the Silky-tailed Nightjar migratory?
No. It is generally regarded as a resident species. Local movements may occur, but regular long-distance migration has not been demonstrated.
What does the Silky-tailed Nightjar eat?
It feeds mainly on flying insects, including moths, beetles and other aerial invertebrates captured during short hunting flights from low perches.
How can the species be found in the field?
Listening is usually more effective than searching visually. Visit suitable humid forest at dusk or before dawn and listen for its repeated song from the forest edge, understorey or nearby low perches.
Where does the Silky-tailed Nightjar nest?
It lays its eggs directly on the ground, usually among leaf litter or low vegetation. A typical clutch contains two pale or white eggs.
Is the Silky-tailed Nightjar endangered?
It is currently classified as Least Concern globally. However, forest destruction and fragmentation remain important concerns, particularly in the Atlantic Forest, and its population size and trend are not well known.
References
- IOC World Bird List
- IUCN Red List of Threatened Species
- Ornitología Neotropical
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