Crescent ant pitta
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Crescent ant pitta ( Grallaricula lineifrons ) |
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| Grail aricula lineifrons | ||||||||||||
| ( Chapman , 1924) |
The half-moon ant pitta ( Grallaricula lineifrons ) is a species of bird from the family of the ant pittas (Grallaridae). He is an inhabitant of humid mountain forests in northwestern South America, where he hunts various insects. Although the species had already been described on the basis of a dead specimen in the mid-1920s, living individuals could only be observed for the first time more than 50 years later. Another 40 years passed before a nest was first described. The continued existence of the half-moon ant pitta is potentially threatened by the destruction of its habitat, but the species is currently not considered to be specifically endangered.
features
Physique and appearance
Like all members of his family, the half-moon ant pitta is a rather small bird, with a round body. This impression is mainly created by the very short tail and the rounded head shape with a short, black beak and is reinforced by the short, wide wings. The legs, on the other hand, are very long and thin and start quite far back on the body. The feet are relatively large and have long toe joints . Adult specimens reach a size between 11.5 and 12 cm. Males usually become a little heavier, their weight is between 20.5 and 22.5 g. Weighted females, on the other hand, were between 20 and 22 g. Beyond that, however, there is no visible sexual dimorphism in the species . Half-moon ant pittas are among the most conspicuously colored members of their family, whose representatives otherwise tend to have more subtle colors. On the back there is a typical, brownish olive green, the upper side of the wings and the tail are similar, but generally a bit darker and more brownish in color. The hand wings and larger hand covers as well as the thumb wing are lined with a yellowish-cream color. The head and neck show a dark sooty gray, which turns into a pure black on the forehead, the ear covers, below and immediately in front of the eyes. In contrast to this, a wide, crescent-shaped stripe in white runs vertically over the reins to the hood , which has also given the species its common name . Another, much smaller, white area is also found behind the eye, the iris of which is colored a dark brown. There are conspicuous, ocher-yellow spots on the sides of the neck. The same color can also be found on the rear part of the broad cheek stripe, but there increasingly turns into white tones towards the front. The center of the chin and the upper part of the throat are white and surrounded by two black stripes, giving the appearance of an upside-down black V from the front. The basic color of the underside is mostly a light white, but this is replaced by a washed-out ocher yellow towards the flanks as well as in the upper chest and lower throat areas. The entire underside is traversed by a vertically aligned striped pattern in black. This pattern can vary from bird to bird, but is usually narrower in the abdomen than on the chest. The under tail feathers are yellow ocher. With a brownish-olive-green basic color, the sides and flanks correspond more to the upper side, but are also striped black. The underside of the wings is mostly also brownish-olive green, the hand wings are white on this side with black or dark gray tips. Legs and feet are gray to blue-gray in color, although this dark color does not occur in any other ant pitta except for the half-moon ant pitta.
Fledglings
For the juvenile plumage of the species there is only one description from 1994, which was made on the basis of a male specimen from northern Ecuador. The basic color of the plumage of this bird largely corresponded to that of the adults , but there were fluffy, down-like feathers with a dull, reddish-brown color on the hood and neck. The brownish-olive-green color on the back and on the upper side of the wings is apparently still interspersed with reddish-brown components in young birds. The upper hand and arm covers are also lined with a very narrow cream color. The abdomen is a little lighter and shows more cream-colored parts than in adult birds.
Habitat and behavior
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Crescent ant pittas inhabit moist cloud and cloud forests at certain altitudes in the Andes , although they seem to prefer forests with not particularly dense undergrowth . Rosaceae of the genus Polylepis are typical of these forest forms . However, sightings are also reported with a certain regularity from relatively dense bamboo forests, dominated by species of the genus Chusquea . The birds spend most of their lives in the lower levels of the forest, but are almost never seen on the ground. Although basically capable of flight, they move almost exclusively over branches and trunks, running and hopping, and are able to hold onto very thin, vertically growing branches. The birds live either solitary or in pairs, with repeated sightings of the same pair in the same location could indicate some territoriality. The species evidently does not form swarms with each other or with other species. A typical behavior for the species is an almost motionless remaining in the same place for long periods of time, whereby only a slow, rhythmic turning movement of the trunk can be seen. The exact function of this behavior is unclear. The birds often react to disturbances with a quick, excited flapping of their short wings. The species is a resident bird that does not take part in the seasonal bird migration .
nourishment
The prey spectrum and hunting behavior of the half-moon ant pitta have so far hardly been researched. The stomach contents of some birds that were examined contained the remains of small spiders, adult beetles and their larvae, as well as other arthropods that could not be identified . It is therefore assumed that they are more or less pure insectivores. Some researchers report that observed specimens appeared to be looking specifically for insects that had been startled by humans. This behavior suggests that the birds may also be able to follow other large mammals such as spectacled bears or tapirs as they forage .
Reproduction
The reproductive behavior of the species was almost completely unknown for a long time, until the beginning of the 2010s only the above-mentioned description of a single young bird was available. Many aspects, such as courtship behavior or the period of the breeding season, are still undescribed. However, when compared with related species, it can be assumed that they are largely monogamous birds. In February 2012, researchers succeeded for the first time in discovering a nest of the crescent ant pitta in a forest above the village of Papallacta in northeast Ecuador at an altitude of around 3300 m. This nest was at a height of around 3.6 m above the ground and was on a knot of three individual tendrils hanging from a branch of a Polylepis tree. On this basket-like mesh, the birds had laid a flat base of 13.5 to 15 cm in diameter made of short sticks, leaf stalks and moss, on which the actual nest was finally built. It was about 11 cm wide, cup-shaped construction with about 5.5 cm high edges. The nest consisted of the same materials as the base, but was additionally lined on the inside with root fibers, grass stalks and soft plant fibers. At the time of discovery, the incubation process was already well advanced, and the researchers estimated that the individual nestling would only need a few days to fled. The young bird was covered all over with soft, rust-brown down , the beak was black, the inside of the mouth was conspicuously colored orange. Again by comparison with other Grail aricula species, it can be assumed that the young birds are initially completely naked after hatching and that the down dress only develops after the first week of life, but is still worn for some time after they have fledged. Both adult birds took care of feeding the nestlings equally by constantly bringing in small insects from the immediate vicinity. They never moved more than 30 m away from the nesting site during the observed period and were noticeably quiet. Only a soft, low whistling sound could occasionally be heard during the delivery of food or while catching prey. While observing this nest, the researchers also noticed two other half-moon ant pittas that were carrying small amounts of building material in their beaks and may therefore be in the nest-building phase. However, the potential nesting site could not be found. In the following years two more, albeit abandoned, nests were discovered in the same area, which with some probability can be assigned to the crescent ant pitta. In one of the two nests the remains of a destroyed egg were found, the shell of which had a pale green to green-blue base color and was speckled with irregular brown and cinnamon-colored spots and spots.
Utterances
The utterance of the species most frequently heard and interpreted as a song is a sequence of up to 20 short tones that become louder and more shrill towards the end. They should be something like pu - pu - pu - pe - pe - pee - pee - pi - pi - pi? sound. In addition, a possible alarm call is known, which should sound more like a hard clip - clip - clip and is presented in the event of a fault. Both sexes seem to sing alike. The call of the young birds should be very similar to that of the adults, but generally sound a little deeper and rougher.
Spread and endangerment
The crescent ant pitta is endemic to the northern regions of the Andes in Ecuador and Colombia. Its distribution area is limited to altitudes between 2900 and 3500 (Ecuador) or 3700 m (Colombia). The mountain forests populated there are each just below the tree line and are often characterized by steep slopes. However, the species does not appear to be found above the tree line. While the half-moon ant pitta was only known from a single site in northeast Ecuador in the first 50 years after its discovery, the known range has increased significantly since the 1970s due to a series of new sightings. It now extends roughly from Caldas in central Colombia to Loja in southern Ecuador. It is still unclear to what extent this is a contiguous area or whether it is more of a series of areas that are isolated from one another. The extent of the entire known distribution area is a little more than 8100 km², of which only about 1150 km² are in Ecuador. However, there appear to be higher population densities in this country, where a number of “hotspots” with a particularly large number of specimens of the species have been found. These include the slopes of the two mountains Cerro Mongus and Cerro Acanama , the area around Papallacta and the Guandera region in the Carchi province . Following the first description in 1924 using a female specimen from Ecuador, it was not until 1976 that living individuals of the species could be found for the first time, this time in Colombia. This was accompanied by the first sighting of male birds. It was not rediscovered in Ecuador until 1991. Because of the very specific requirements on its habitat, the crescent ant pitta is particularly susceptible to man-made changes in its habitat. In particular, the deforestation of the Polylepis trees for the production of firewood should be mentioned, which is often the only available fuelwood source in the region. The species inhabits several national parks and similar protected areas, especially in Colombia, which is why it is better protected there than in neighboring Ecuador, where protection regulations are often poorly controlled. After only vague assessments of the threat status had previously been possible due to the rarity of sightings, the IUCN classified the species as near threatened from 2004 onwards . In the latest assessment from 2019, the organization downgraded the crescent ant pitta for the first time to the lowest risk level of least concern (“not endangered”), referring to an apparently stable development of the population.
Systematics and research history
The first scientific description of the half-moon ant pitta dates back to 1924 and goes back to the American ornithologist Frank Michler Chapman . The holotype is a dead specimen that a bird collector brought back from northern Ecuador the year before. Mainly because of the remarkably high location and the unusual color of the plumage, Chapman described a new genus for the species and gave it the scientific name Apocryptornis lineifrons . Chapman speculated in his work that the species could possibly be a transitional form between ant pittas of the genus Grallaria and mosquito eaters of the genus Conopophaga . The specific epithet is a combination of the two Latin terms linea for "line" and frons or frontis for "forehead", "brow" and refers to the drawing of the plumage on the face of the birds. James Lee Peters placed the species in the genus Grallaricula in 1951 , which is still generally accepted in the specialist literature despite the peculiarities of the species. Which other species are closest to the half-moon ant pitta has not been conclusively clarified. The Danish ornithologist Niels Krabbe names the gray-headed ant pitta ( G. nana ) as the closest relative, while Graves et al. determine at least superficial similarities with the ornamental ( G. peruviana ), the ocher forehead ( G. ochraceifrons ) and the scale ant pitta ( G. loricata ). The species is considered to be monotypical , geographical variations are also absent, as far as known.
Web links
- Recordings of calls and chants at xeno-canto.org
Individual evidence
- ↑ Harold F. Greeney: Antpittas and Gnateaters . Christopher Helm, London 2018, ISBN 978-1-4729-1964-9 , pp. 68-69 .
- ↑ a b c Harold F. Greeney: Crescent-faced Antpitta (Grallaricula lineifrons). In: Birds of the World. 2020, accessed on August 1, 2021 .
- ↑ a b c d e f g h i j Harold F. Greeney: Antpittas and Gnateaters . Christopher Helm, London 2018, ISBN 978-1-4729-1964-9 , pp. 439-444 .
- ^ Nathan H. Rice: Phylogenetic Relationships of Antpitta Genera (Passeriformes: Formicariidae) . In: The Auk . tape 122 , no. 2 , 2005, p. 673-683 , doi : 10.1642 / 0004-8038 (2005) 122 [0673: PROAGP] 2.0.CO; 2 .
- ^ Mark B. Robbins, Niels Krabbe, Gary H. Rosenberg, Robert S. Ridgely, Francisco Sornoza Molina: Notes on the Natural History of the Crescent-Faced Antpitta . In: The Wilson Bulletin . tape 106 , no. 1 , 1994, p. 169-173 .
- ↑ Harold F. Greeney, Marcello Jipa: The nest of Crescent-faced Antpitta Grallaricula lineifrons in north-east Ecuador . In: Bulletin of the British Ornithologists' Club . tape 132 , no. 3 , 2012, p. 217-220 .
- ^ Carlos Lehmann, JR Silliman, E. Eisenmann: Rediscovery of the Crescent-Faced Antpitta in Colombia . In: The Condor . tape 79 , no. 3 , 1977, pp. 387-388 , doi : 10.2307 / 1368021 .
- ↑ Grallaricula lineifrons in the Red List of Threatened Species of the IUCN 2020.2. Listed by: BirdLife International, 2019. Retrieved August 3, 2021.
- ↑ Niels Krabbe: Arid valleys as dispersal barriers to high-Andean forest birds in Ecuador . In: Cotinga . tape 29 , 2008, p. 28-30 .
- ^ Gary R. Graves, John P. O'Neill, Theodore A. Parker: Grallaricula ochraceifrons, a new species of antpitta from northern Peru . In: The Wilson Bulletin . tape 95 , no. 1 , 1983, p. 1-6 .