Long-tailed day sleeper
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Long-tailed day sleeper ( Nyctibius aethereus ) |
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| Nyctibius aethereus | ||||||||||
| ( Wied , 1820) |
The long-tailed day dormouse ( Nyctibius aethereus ) is a nocturnal species of bird belonging to the day dormouse genus . The species inhabits the tropical forests of South America and was first described scientifically in 1820 by the German naturalist Maximilian zu Wied-Neuwied .
Description and behavior
description
With a size of 42 to 56 cm and a weight of 280 to 447 g, long-tailed day sleepers are among the larger representatives of day sleepers. The birds' heads appear large and slightly rounded when not stretched out. In particular, the large eyes with yellowish irises, adapted to a nocturnal lifestyle, and the short but laterally strongly enlarged and pointed beak are striking. The wings and tail are quite long in relation to the stocky body, especially the elongated tail feathers are used to distinguish them from other species of the genus. Further unique selling points are the slightly upwardly curved feather tips on the shoulders of the birds, as well as the lack of white spots of color in the plumage. Instead, it shows a predominantly brownish color, which plays an important role in camouflage for the animals. At the top this is speckled with yellow-brown and blackish spots and stripes. There are no visually perceptible differences between the sexes. Immediately after hatching, juvenile long-tailed day sleepers are covered in soft, white down . Over time, the young birds develop a light cinnamon color before they take on the brownish camouflage color of their parents.
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Behavior and nutrition
The long-tailed day sleeper is only active at night. During the day, the birds rest more or less motionless on a dead branch up to 20 m above the ground, whereby their plumage makes them look like an extension of their resting place. If a potential enemy approaches or the animals are disturbed, they stretch their bodies vertically with slow movements, which increases the camouflage effect. In this alert position, the eyes are wide open and not closed until the possible threat has passed. During the night, long-tailed day sleepers wait on an exposed seat guard for prey to pass by, and pounce on it with a quick, acrobatic movement. The exact composition of the diet has not yet been researched, but - like other day sleepers - it is likely to consist primarily of flying insects. Flying termites , moths and click beetles are definitely captured . In its entire range, the species is considered a resident bird .
Reproduction
The detailed reproductive behavior of the long-tailed day sleeper has not yet been fully researched; reports have only been made from Paraguay and French Guiana . In these cases, the beginning of the brood coincided with the end of the dry season in the respective region - August in Paraguay, July in French Guiana. The adult birds do not construct a real nest; instead, the female lays a single egg in a small hollow on the top of a broken tree stump. The egg has a size of about 38.2 × 26.0 mm and is probably incubated for about three to four weeks until the young birds hatch.
Vocalizations
The most commonly heard chant of the species is described as a gently performed waa - oo - uh or ra - ooh , with the emphasis on the second syllable. On average, this call is repeated about every seven seconds. The singing can be heard mainly at night when the animals are more active, and the birds seem to sing especially on nights with bright moonlight.
Spread and endangerment
The long-tailed day sleeper inhabits evergreen, tropical forests on the South American continent. He prefers the lowlands up to a height of about 750 m above sea level, although there are unconfirmed reports of sightings up to 1500 m. The core of the contiguous distribution area forms the Amazon basin , in the north it extends into eastern Venezuela and the Guyanas , while in the west the eastern regions of Ecuador and Peru are reached. Another noteworthy, but isolated distribution area exists in the southeast of Brazil and extends to the easternmost regions of Paraguay and Argentina . Two smaller, equally isolated populations exist in northeastern Brazil and western Colombia . The IUCN classifies the long-tailed Tagschläfer with stand 2016 as not endangered (status least concern ), and performs as a justification of the huge range of the species. However, the organization also notes a general decline in population numbers.
Systematics
Maximilian zu Wied-Neuwied described the long-tailed day sleeper for the first time in 1820 as Caprimulgus aethereus and thus initially placed it among the goat milkers . In addition to the nominate form N. a. aethereus considers two further subspecies to be valid, which differ mainly in terms of size and color. Both N.A. longicaudatus and N. a. chocoensis were initially considered as a subspecies of a separate species within the genus Caprimulgus and later Nyctibius . It was not until the 1940s that ornithologist James Lee Peters added them as subspecies to N. aethereus based on “rather scant evidence” , which was subsequently retained. Here he mainly referred to the very similar sounding utterances of the birds.
- N / A. aethereus ( Wied , 1820); southeastern Brazil, northeastern Argentina, southeastern Paraguay
- N / A. longicaudatus ( Spix , 1825); Amazon Basin; smaller than the nominate form, especially more yellow-brown on the chest
- N / A. chocoensis Chapman , 1921; western Columbia; smaller, generally darker coloring than the nominate form
Web links
- Recordings of vocalizations at xeno-canto.org
- Videos and audio recordings at ebird.org (English)
Individual evidence
- ^ Sulli Gibson: Long-tailed Potoo Nyctibius aethereus - Appearance. In: cornell.edu. Cornell Lab of Ornithology, 2014, accessed November 22, 2019 .
- ^ A b Sulli Gibson: Long-tailed Potoo Nyctibius aethereus - Behavior. In: cornell.edu. Cornell Lab of Ornithology, 2014, accessed November 22, 2019 .
- ^ Sulli Gibson: Long-tailed Potoo Nyctibius aethereus - Diet and Foraging. In: cornell.edu. Cornell Lab of Ornithology, 2014, accessed November 22, 2019 .
- ^ Sulli Gibson: Long-tailed Potoo Nyctibius aethereus - Breeding. In: cornell.edu. Cornell Lab of Ornithology, 2014, accessed November 22, 2019 .
- ^ Sulli Gibson: Long-tailed Potoo Nyctibius aethereus - Sounds and Vocal Behavior. In: cornell.edu. Cornell Lab of Ornithology, 2014, accessed November 22, 2019 .
- ^ Sulli Gibson: Long-tailed Potoo Nyctibius aethereus - Distribution. In: cornell.edu. Cornell Lab of Ornithology, 2014, accessed November 22, 2019 .
- ↑ Long-tailed Potoo Nyctibius aethereus. In: iucnredlist.org. BirdLife International, 2016, accessed November 22, 2019 .
- ^ Sulli Gibson: Long-tailed Potoo Nyctibius aethereus - Systematics. In: cornell.edu. Cornell Lab of Ornithology, 2014, accessed November 22, 2019 .