Mexico day sleeper
| Mexico day sleeper | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Mexico day sleeper ( Nyctibius jamaicensis ) |
||||||||||
| Systematics | ||||||||||
|
||||||||||
| Scientific name | ||||||||||
| Nyctibius jamaicensis | ||||||||||
| ( Gmelin , 1789) |
The Mexican day sleeper ( Nyctibius jamaicensis ) is a nocturnal species of bird belonging to the day sleeper genus . It inhabits parts of Central America as well as some of the larger islands of the western Caribbean and was originally considered a subspecies of the very similar Urutau day sleeper .
Description and behavior
description
The Mexican day sleeper is a medium-sized representative of its genus, depending on the subspecies and gender, it can reach a size of 36 to 45 cm with a weight of 210 to 320 g. The males tend to be somewhat larger than their female counterparts, but there is no further sexual dimorphism . The head is relatively large and rounded in shape with an extremely broad but short beak. The large eyes, adapted to a nocturnal lifestyle, have a striking yellow iris . The coloring of the birds' plumage plays an important role in their camouflage and is primarily kept in various shades of brown and speckled with black, gray and white spots. The feathers on the abdomen and chest tend to appear in slightly paler tones, while a black mottling can be found on the throat. Young animals are covered in soft, white down immediately after they hatch; their plumage takes on an increasingly dark color over time, until they finally adopt the typical camouflage pattern of adult birds.
behavior
Like all day-sleepers, the species is exclusively nocturnal, during the day the animals rest almost motionless on a shady branch near the edges of the forest and clearings, where they look like part of the branches due to their plumage and are well camouflaged. Only extremely slow movements of the head are perceptible with continued observation. In the event of danger, the birds quickly move into a stretched "alarm posture" which further intensifies the camouflage effect. There is evidence of a strong connection to favorite sleeping places, which are used every day for months or even years. Outside the breeding season, Mexican day sleepers lead a solitary way of life, whether there is a pronounced territorial behavior is unknown.
nutrition
Mexikotagschläfer feed mainly on insects, including Bock , sugar and beetles and katydids and moths . Furthermore, small birds such as the brown-eared monkey are occasionally preyed on . The nocturnal hunt starts from an exposed seat guard , from where the prey flying past is waited for and thrown down on it with a quick movement. For the consumption of the prey animal is first returned to the seat control room. In the vicinity of human settlements, there are reports of Mexico day sleepers waiting on street lamps for insects attracted by the light.
Vocalizations
The call of the Mexican day sleeper is usually described as a sequence of three to six rough or guttural kwah sounds, reproduced at short intervals , with the first sound being drawn longer than the following. Less frequent reports of an abrupt, emphatic rrah , which could be an alarm call. Slight variations of the song are used to distinguish the subspecies N. j. abbotti is drawn from the nominate form .
Reproduction
The reproductive behavior of birds has so far rarely been observed and is therefore poorly researched. A simple recess on a branch or tree stump serves as a nesting site, in which the female lays a single white egg with brown, black and purple spots. The size of the egg is around 40 × 30 mm. During the day, the egg is incubated by the male, with both adult birds taking part in rearing the young. In case of danger the young animal disappears more or less completely in the breast plumage of the adult bird sitting on it. The time it takes for the young to hatch and the subsequent brood care is still unknown.
Spread and endangerment
The Mexico day sleeper inhabits open and semi-open areas with some scattered trees to rest on during the day. These include the edges of dry as well as moist forests, mangroves , bushland or golf courses in areas populated by humans. He basically prefers the flatlands, the maximum height up to which he could be detected is 1500 m above sea level. Its range is the northernmost of all day sleeper species and extends in the north to the height of the Mexican states of Sinaloa in the west and Tamaulipas in the east. It follows both coastlines to the north-west of Costa Rica and the north-east of Honduras . With the exception of the Yucatán Peninsula , however, hardly any larger areas in inland Central America are populated. There are also populations on the Caribbean islands of Jamaica and Hispaniola . In the case of isolated sightings in Cuba and on some small islands off Puerto Rico , it is likely to be random visitors .
As of 2016, the IUCN classifies the Mexican day sleeper as not endangered (status least concern ), but assumes a generally decreasing population trend. The number of wild individuals is located in the range of 50,000 to 500,000 specimens. Due to the lack of or very rare sightings in recent decades, the species is locally endangered in El Salvador .
Systematics
The Mexican day sleeper was originally classified as a subspecies of the Urutau day sleeper ( Nyctibius griseus ) first described by the German naturalist Johann Friedrich Gmelin in 1789 , to which it is very similar in size and appearance. Research from the 1970s and 80s revealed significant differences in the vocalizations of the animals, which led to the reassignment of the northern populations as Nyctibius jamaicensis . More recent phylogenetic studies from 2009 also provided evidence that N. jamaicensis and N. griseus are sister species. In addition to the nominate form N. j. jamaicensis usually four other subspecies are considered valid, which are mainly distinguished on the basis of their geographical distribution and their plumage. The validity of the subspecies status of N. j. lambi and N. j. costaricensis is doubted by some researchers, who only show more pronounced clinical variations of N. j. see mexicanus . Furthermore, N. j. abbotti will receive the status of a separate species in the future based on significantly longer chants, but further research is necessary in this regard.
- N.j. jamaicensis ( Gmelin , 1789); Jamaica
- N.j. mexicanus Nelson , 1900; eastern and southern Mexico to Honduras
- N.j. costaricensis Ridgway , 1912; northwest and central Costa Rica
- N.j. abbotti Richmond , 1917; Hispaniola
- N.j. lambi Davis , 1959; Mexican Pacific coast from Sinaloa to Colima
Web links
- Recordings of vocalizations at xeno-canto.org (English)
- Photos and videos at ebird.org (English)
Individual evidence
- ^ Daniel Gu, Robert A. Behrstock, Thomas S. Schulenberg: Northern Potoo Nyctibius jamaicensis - Appearance. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 21, 2019 .
- ^ A b Ann Haynes-Sutton, Audrey Downer, Robert Sutton: A Photographic Guide to the Birds of Jamaica . Christopher Helm, London 2009, ISBN 978-1-4081-0743-0 , pp. 156-157 .
- ^ A b Daniel Gu, Robert A. Behrstock, Thomas S. Schulenberg: Northern Potoo Nyctibius jamaicensis - Behavior. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 21, 2019 .
- ^ Daniel Gu, Robert A. Behrstock, Thomas S. Schulenberg: Northern Potoo Nyctibius jamaicensis - Diet and Foraging. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 21, 2019 .
- ^ Daniel Gu, Robert A. Behrstock, Thomas S. Schulenberg: Northern Potoo Nyctibius jamaicensis - Introduction. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 21, 2019 .
- ^ Daniel Gu, Robert A. Behrstock, Thomas S. Schulenberg: Northern Potoo Nyctibius jamaicensis - Sounds and Vocal Behavior. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 21, 2019 .
- ^ Daniel Gu, Robert A. Behrstock, Thomas S. Schulenberg: Northern Potoo Nyctibius jamaicensis - Breeding. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 21, 2019 .
- ^ A b Daniel Gu, Robert A. Behrstock, Thomas S. Schulenberg: Northern Potoo Nyctibius jamaicensis - Distribution. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 21, 2019 .
- ↑ Northern Potoo Nyctibius jamaicensis. In: iucnredlist.org. BirdLife International, 2016, accessed November 21, 2019 .
- ^ Daniel Gu, Robert A. Behrstock, Thomas S. Schulenberg: Northern Potoo Nyctibius jamaicensis - Systematics. In: cornell.edu. Cornell Lab of Ornithology, 2011, accessed November 21, 2019 .
- ↑ M. Cohn-Haft, GM Kirwan: Northern Potoo (Nyctibius jamaicensis). In: hbw.com. Handbook of the Birds of the World Alive, 2014, accessed November 21, 2019 .