Andean day sleepers
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Andean Day Sleeper ( Nyctibius maculosus ) |
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| Ridgway , 1912 |
The Andean day dormouse ( Nyctibius maculosus ) is a nocturnal species of bird belonging to the day dormouse genus . The species inhabits the mountain forests of western South America and was first described scientifically in 1912 by the American ornithologist Robert Ridgway .
Description and behavior
description
The Andean day sleeper is around 34 to 38 cm tall and weighs around 145 to 195 g, making it one of the larger representatives of the genus. The overall shape of the body appears compact, the long tail and the rounded head with the large eyes adapted to a nocturnal lifestyle are striking. The iris is yellowish-orange in color. The beak is very broad and tapering towards the end. The males tend to be somewhat larger and heavier than the females; unlike most other day-sleeper species, there is also an - albeit lesser - sexual dimorphism in the color of the plumage . This is mainly kept in brown, gray and black tones and plays an important role in camouflaging the animals during the day. On the shoulders of the male there is a characteristic white spot, which is darker in the female and can sometimes turn into ocher.
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Behavior and nutrition
Like all day sleepers, the Andean day sleeper is exclusively nocturnal. During the day, the birds rest more or less motionless on branches or broken tree stumps, which, in conjunction with their plumage, makes for excellent camouflage. These resting places can be very high and are sometimes visited over a period of several weeks. During the night, the animals wait in a waiting room for prey animals to pass by, which are then pushed down with a quick movement. Insects such as flying beetles or moths serve as food . In its entire range, the species is considered a resident bird .
Reproduction
Nothing is known about the beginning of the breeding season, basically the reproductive behavior of the species has so far been poorly researched. It is certain that the female calls the male to her with short chants before mating . The nest and eggs are blank, but it can be assumed with some certainty that, as with other day sleepers, a single egg is laid on a tree stump or in the recess of a branch.
Vocalizations
The song of the Andean day sleeper heard most often is described as a loud, sloping, raa - àa or aah - aa that is repeated every few seconds over a period of two to three minutes. According to some researchers, the sounds are said to resemble a person's screams. This song is performed from regularly changing seats, which are distributed in a radius of about 700 m around the resting place of the birds and can be located at a distance of 50 to 75 m from each other. Slower, hollow-sounding vocalizations, which should sound like wok - wok - wok or bu - bu - bu , are heard less often - especially when landing or in the event of interference .
Spread and endangerment
The Andean day sleeper is the only real highland dweller among the day sleepers, its range is limited to the Andes mountain range in the west and northwest of the South American continent. It stretches from Venezuela through Colombia , Ecuador and Peru to Bolivia . The species has been recorded at altitudes of around 1800 to 2800 m, where it inhabits moist, evergreen cloud and cloud forests . In the entire distribution area, sightings are considered rather rare, but it cannot be ruled out that the birds are often overlooked due to their camouflage and nocturnal lifestyle. The IUCN classifies the Andean day sleeper as not endangered as of 2016 (status least concern ), which is mainly due to the geographically very large distribution area. At the same time, however, the organization also notes a generally declining population trend.
Systematics
The species is currently considered monotypical . Phylogenetic examinations as well as protein analyzes of the two species indicate that the Andean day dormouse and the white-winged day dormouse ( Nyctibius leucopterus ) are most certainly sister species. However, due to morphological and geographical differences, neither are considered conspecific .
literature
- Nigel Cleere, Dave Nurney: Nightjars - A Guide to Nightjars and related Nightbirds . Pica Press, Susex 1998, ISBN 978-1-873403-48-8 ( limited preview in Google book search). See Chapter 19: Andean Potoo (Nyctibius maculosus)
Web links
- Audio recordings of utterances at xeno-canto.org
- Photos and audio recordings at ebird.org (English)
Individual evidence
- ↑ Thomas S. Schulenberg, Guy M. Kirwan: Andean Potoo Nyctibius maculosus - Breeding. In: cornell.edu. Cornell Lab of Ornithology, 2012, accessed November 25, 2019 .
- ^ Thomas S. Schulenberg, Guy M. Kirwan: Andean Potoo Nyctibius maculosus - Sounds and Vocal Behavior. In: cornell.edu. Cornell Lab of Ornithology, 2012, accessed November 25, 2019 .
- ↑ Andean Potoo Nyctibius maculosus. In: iucnredlist.org. BirdLife International, 2016, accessed November 25, 2019 .
- ↑ Thomas S. Schulenberg, Guy M. Kirwan: Andean Potoo Nyctibius maculosus - Systematics. In: cornell.edu. Cornell Lab of Ornithology, 2012, accessed November 25, 2019 .