Silky-tailed Nightjar Antrostomus sericocaudatus

  • Order: Caprimulgiformes
  • Family: Caprimulgidae
  • Polytypic: 2 subspecies
  • Authors: F. A. Wilkinson Wilkinson
Sections

Breeding

Nest - No nest is constructed. Two-egg clutches are laid directly on the ground on bare patches or on leaf-litter near open areas.

Breeding Dates – C. s. mengeli breeds from August - December coinciding with the latter half of the dry season through the beginning of the rainy season in the southwestern Amazon Basin (Wilkinson 2009).

Egg variation of the Silky-tailed NightjarEggs – Eggs of C. s. mengeli are elliptical, smooth, pale pinkish-orange in color with dark maroon specks concentrated at the blunt end and are relatively conspicuous. Concentration of the specks and color intensity vary. Eggs (n = 22) averaged 27.1 ± 2.1 mm (range = 21.8–31.0 mm) by 21.4 ± 3.1 mm (range = 18.0–30.7 mm), and had a mass of 6.68 ± 1.2 g (range = 4.0–8.5 g) (Wilkinson 2009).

Schönwetter (1960-72) states eggs from the nominate form are 29.7 mm (range = 28.0-31.0) by 21.5 mm (range = 21.0-23.0, n = 4).

Incubation – Incubation period ~ 18 days. Both adults incubate with the female on the nest during the day and the male on at night. Nest relief during incubation takes place right before dawn and after dusk.

Nestling and fledgling development – The semi-precocial chicks hatch on successive days, are covered with golden down, weigh 6–7 g, are mobile within 24 hrs and defecate away from the nest. Dark brown pin feathers begin to appear by day 3, and nestlings can “hop” over short distances (up to 6 m). By day 11/12, nestlings are capable of flying ca. 6 m; the light colored tips of the outer tail feathers are visible in flight. The sheaths of the alar feathers begin to break, displaying brown tips and coverts are grayish brown with distinguishable brown circular markings. Development of pin feathers along the capital and caudal tracts continue making them more cryptic. At this age nestlings become active during the day, frequently emerging from under the female to preen and stretch their wings. Nestlings at CCBS were observed tossing leaf litter and pecking at decaying material around the nest-site perhaps foraging for small insects or to pick up small granules to aid digestion (Jenkinson and Mengel 1970), a behavior observed for young Puerto Rican Nightjars (Caprimulgus noctitherus; Vilella 1995), Ocellated Poorwills (Nyctiphrynus ocellatus; FAW, unpubl. data), and adult Eastern Whip-poor-wills (Caprimulgus vociferus; Jones 1933). Nestlings have been observed to stay within the nest-site area, with or without an adult present, until about age 24 days. Afterwards, it is not well documented if they fledge or remain in the area.Nestling of the Silky-tailed Nightjar at age 12 days old.

Parental care – Both adults alternate in feeding the young via regurgitation; one adult flies off the nest as the other one returns to feed the young. Nestlings often emerge and try to solicit food by pecking at the adult’s bill.

Recommended Citation

Wilkinson, F. A. W. (2011). Silky-tailed Nightjar (Antrostomus sericocaudatus), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.sitnig1.01