Giant day sleeper
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Giant day sleeper |
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| Nyctibius grandis | ||||||||||
| ( Gmelin , 1789) |
The giant day sleeper ( Nyctibius grandis ) is a species of bird belonging to the day sleeper genus . The nocturnal species is widespread in large parts of South America and was first scientifically described in 1789 by the German naturalist Johann Friedrich Gmelin .
Description and behavior
description
The giant day sleeper is the largest representative of its genus with a size of around 48 to 60 cm with a wingspan of around 70 to 80 cm. The weight of the animals varies between 360 and 650 g, female specimens tend to be somewhat larger and heavier than their male counterparts, but there is no further sexual dimorphism . Giant day sleepers have an elongated body with a long tail, a strong neck and a large, rounded head. Particularly noticeable are the dark brown to almost black eyes, which are adapted to a nocturnal lifestyle, and the wide beak of the animals. The plumage of the adult birds shows the gray-brown-speckled coloring characteristic of day sleepers, with which the animals are perfectly camouflaged on the trees on which they rest during the day. A row of white bars can only be found on the tail feathers. Juvenile specimens tend to be lighter in color; a number of white spots on the chest, back, sides and head are particularly noticeable.
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behavior
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Giant day sleepers are exclusively nocturnal; they spend the day almost motionless on the branches of large trees. Here they align themselves with their eyes narrowed to slits and an upright hood along the branch, which, together with their gray-brown plumage, makes them look like a broken stump. In the event of danger, the body is stretched in one quick movement, the eyes completely closed and the hood put on to look even more like part of the branches. The animals lead a predominantly solitary way of life, but a pronounced territorial behavior is not known. In its entire range, the species is considered a resident bird .
nutrition
The birds' diet consists mainly of insects such as beetles , grasshoppers and leaf locusts , but small bats are also occasionally captured and eaten. During the nocturnal hunt, the giant day sleeper waits for prey to pass by in an exposed seat guard on a branch in the immediate vicinity of the resting place. If this has been spotted, the birds start with a quick movement and beat the prey in flight before they return to their branch to feed. The same attendant is very often visited on several consecutive nights.
Vocalizations
The giant day sleeper is known for its distinctive vocalizations, which it utters both in flight and when resting. The most common utterance is described as a loud, sloping baaaao or buaaaa , which is said to resemble the calls of frogs or the choking of a person. Other calls that are heard less often sound like whoap , oorrr or oorroo , with the last two sounds supposed to be similar to those of owls . The animals often let some time pass between the individual calls.
Reproduction
The breeding season can vary widely within the range. There are reports of breeding processes in Guyana in February, in Colombia in March and April, in Venezuela in June and August and in Suriname in November. The reason for this is assumed to be based on the rainy season , the onset of which in South America can vary greatly depending on the region.
The nest is usually built high up in the branches of tall trees; the construction is not very complex, usually a natural crack in a branch is simply used. After choosing the nesting site, the female lays a single egg, 52 × 38 mm in size. This shows a white basic color with dark brown, gray and light purple spots. After hatching, the young bird is cared for in the nest for at least 55 days before it fledges and leaves it. After about 14 days, juvenile birds begin to imitate their parents' camouflage behavior when in danger. The species is monogamous, but whether both adult birds also take part in brood care is unclear, as the sexes cannot be distinguished visually and, in the case of joint rearing, both parents do not stay at the nest at the same time.
Spread and endangerment
The giant day sleeper lives in moist, evergreen forests and can be found mainly near watercourses and lakes as well as at the transitions to more open terrain. It generally prefers lower lying areas, the maximum geographic altitude at which it occurs is less than 1000 m. Its distribution area extends over large parts of northern South America and extends in the north along the east coast of Central America to the south-easternmost Mexico . An isolated population also exists in southeastern Brazil .
The IUCN classifies the giant day sleeper as not endangered (status least concern ) , mainly due to its large distribution area , but reports a general decline in population. As of 2016, the organization assumes a minimum of 500,000 and a maximum of 5,000,000 wild animals. In parts of Brazil, the feathers of birds are ascribed to have the power to move the wearer to observe chastity , which is why the birds are hunted for use in appropriate ceremonies. Furthermore, giant day sleepers represent a part of the diet of Brazil's rural population to a very limited extent. In addition to some species of monkeys ( uncapped capuchins , Geoffroy spider monkeys , coat howler monkeys ), tayras and gray-backed forest falcons are among the natural predators .
Internal system
Johann Friedrich Gmelin described the giant day sleeper in 1789 as Caprimulgus grandis and initially placed it among the goat milkers .
The species is currently considered to be monotypical . In 1963 the two researchers Hugh C. Land and William L. Schult suggested part of the northern population as subspecies N. g. guatemalensis because it has a longer tail and elongated wings as well as a slightly different color than other representatives of the species. However, the proposal did not find official approval.
literature
- Josep del Hoyo, Andrew Elliott, Jordi Sargatal : Barn-owls to hummingbirds . In: Handbook of the Birds of the World . tape 5 . Lynx Edicions, 1999, ISBN 978-84-87334-25-2 , pp. 289-294 .
Web links
- Videos, photos and sound recordings of Nyctibius grandis in the Internet Bird Collection
Individual evidence
- ↑ a b c Grant Slusher: Nyctibius grandis - great potoo. In: animaldiversity.org. Animal Diversity Web, accessed November 12, 2019 .
- ↑ K. Adams: Great Potoo Nyctibius grandis - Appearance. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 12, 2019 .
- ↑ K. Adams: Great Potoo Nyctibius grandis - Behavior. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 12, 2019 .
- ↑ K. Adams: Great Potoo Nyctibius grandis - Diet and Foraging. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 12, 2019 .
- ↑ K. Adams: Great Potoo Nyctibius grandis - Sounds and Vocal Behavior. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 12, 2019 .
- ↑ K. Adams: Great Potoo Nyctibius grandis - Breeding. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 12, 2019 .
- ↑ K. Adams: Great Potoo Nyctibius grandis - Distribution. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 12, 2019 .
- ↑ Great Potoo Nyctibius grandis. In: iucnredlist.org. BirdLife International, 2016, accessed November 12, 2019 .
- ↑ K. Adams: Great Potoo Nyctibius grandis - Conservation. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 12, 2019 .
- ↑ Caprimulgus grandis - JF Gmelin, 1789. In: itis.gov. Integrated Taxonomic Information System, accessed November 12, 2019 .
- ↑ K. Adams: Great Potoo Nyctibius grandis - Systematics. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 12, 2019 .
- ^ Hugh C. Land, William L. Schultz: A Proposed Subspecies of the Great Potoo, Nyctibius grandis (Gmelin) . In: The Auk . tape 80 , no. 2 , 1963, p. 195-196 , doi : 10.2307 / 4082564 .