Somali strangler
| Somali strangler | ||||||||||||
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Somali shrike ( Lanius somalicus ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Lanius somalicus | ||||||||||||
| Hartlaub & Heuglin , 1859 |
The Somali shrike ( Lanius somalicus ) is a songbird belonging to the genus of the real shrike ( Lanius ) within the family of the shrike (Laniidae).
The starling-sized , high-contrast black-gray-white strangler species is common in eastern Africa north of the equator in the region around the Horn of Africa and separately in southern Ethiopia and north and north-west Kenya. It shares the south and south-west part of its range with its sister species, the Taita strangler . It lives singly or in breeding pairs in dry, only sparsely bush-lined savannahs .
Like the majority of representatives of this genus, the Somali shrike is also a hide hunter , who feeds primarily on invertebrates and occasionally on small vertebrates . The species is considered to be a resident bird , but isolated small-scale migratory movements and entries into otherwise unpopulated areas have been observed.
There is hardly any information about the distribution of the Somali strangler. There is also no detailed information on the biology of the species. Currently (2016) it is not listed in any hazard level; at least regionally it does not seem to be rare.
The species is monotypical , no subspecies are described.
Appearance
The Somali shrike is a conspicuous, contrasting, rather short-tailed shrike; he is a little slimmer than his sister species. Its length is 20-21 centimeters, the weight fluctuates around 45 grams. Particularly striking and characteristic is the slate-gray coat, set off in white from the black wings.
The gender dimorphism is limited to minimal differences in color, which cannot be used in field ornithological terms. In females, the axillary feathers (feathers on the lower wing between body and wing) are brownish-gray, not black as in the male. A rust-red color on the flanks, otherwise a common color difference in African shrike, is not developed.
In the south and south-west of the distribution area, its breeding areas overlap with those of the Taita strangler, with whom it can be confused very easily. The Somali shrike is long-tailed, less massive, the gray on the back is more subdued and the white parts on the tail and wings are more extensive. In particular, the arm wings and the shield springs also have white end markings. Overall, however, the two types are difficult to distinguish and are often confused. Juvenile Somali stranglers are significantly lighter, light gray-brown or sand-colored, than juvenile Taita stranglers, whose basic color is a sooty gray.
The forehead, crown, cheeks, neck and upper coat are jet black. The black face mask is completely covered. The rest of the coat and the back are pale slate gray towards the rump. The shoulders are white, as are the bases of the wings . This creates an always visible, quite extensive white wing field when the bird is sitting, and a conspicuous sickle-shaped pattern when it is flying. The arm wings and the umbrella feathers end in white tips, which means that the inner wing edges of the flying bird are finely lined with white and that of the seated white feather regions appear at the tips of the wings. The upper tail-coverts and the rump are almost pure white. The entire underside of the body is white; sometimes the throat area is slightly rusty brown. The clearly stepped tail is black in its basic color. The outer feathers are completely white, the others are drawn extensively in white, only the middle pair is completely black. The underside of the tail is also largely white. The hooked bill is black, as are the legs. The iris is brown.
Young birds are light gray-brown to sand-colored. With the exception of the head and mantle, the top is heavily banded or spotted. The wing covers and the umbrella feathers are clearly yellow-brown edged. Upper tail-coverts and rump are pale yellow-brown, the tail a little darker. The white wing field is largely developed. The face mask is indicated above all in the area of the ear covers. The underside shows slight dark bands, but otherwise resembles the adult.
Mauser
Information on moulting is largely missing. In December, three females in the final stage of a total moult were found in Ethiopia; also in Ethiopia in February two young birds at the end of the feather change in their first adult dress.
Vocalizations
The vocalizations of the species have not yet been adequately researched. Above all, their situational context is largely unknown. In contrast to the Taita strangler, there are a number of very good sound documents.
The most frequent calls seem to be a conspicuous jay-like screeching, which is followed by a mostly two-syllable bright, sharp chirping (often with a clinking sound quality). This basic structure is changed many times. Furthermore, lined up, softly chattering sounds can be heard, which vary the second part of the above-mentioned call. A sound with cooing sound characteristics is described as an alarm call.
distribution and habitat
The range of the Somali strangler is split into two relatively large, completely separate areas. The eastern one is around the Horn of Africa. In the northwest it almost reaches the border area with Eritrea , then runs southwest to south of Addis Ababa and eastwards over the north of Ethiopia to the coast of the Indian Ocean . Somaliland as well as the north and north central part of Somalia are largely populated throughout the area, to the south the distribution area stretches along the coast to south of Mogadishu . The western part is located in the extreme southeast of the Republic of South Sudan , in the north and northern central part of Kenya and extends eastward in a narrow finger to the border of southern Ethiopia and Somalia. The northern border lies in the Afar triangle , but its exact course is unclear. Despite apparently suitable habitats, the species has not yet been identified in northeast Kenya and southeast Ethiopia.
The species lives in significantly drier and less vegetated areas than its sister species, and is therefore almost always spatially clearly separated from it. Dry grass savannahs with isolated bushes, dry areas of acacia - Commiphora savannas, and only very sparse bushy semi-deserts are preferred. It occurs from sea level to heights of about 2000 meters ( Mount Wagar , Somalia, or northern and central Ethiopia), in the western part mostly at heights below 1000 meters.
The species is considered a resident bird, but post-breeding season sightings outside the breeding area make at least occasional, small-scale migratory movements likely. It was found in Baringo County and Isiolo County in sometimes untypically humid habitats.
There is no information on space requirements or the size and type of territories.
Biological details
The species has not been adequately researched. Detailed information on most of the individual biological aspects is not available.
Food and subsistence
The diet of the species consists largely of invertebrates . The Somali shrike also prey on small vertebrates more rarely but regularly .
Large insects dominate the invertebrates, mainly grasshoppers , beetles and fishing rods . Small songbirds and their nestlings are likely to dominate among the vertebrates .
Like most species of the genus Lanius, the Somali shrike is primarily a hunter who searches the ground for prey from a mostly exposed perch. An outer branch of a bush or tree, termite mound, or telegraph poles and telegraph lines serve as a sitting area . If it spies a suitable prey, it slides from the hide and hits it on the ground. Smaller prey is eaten on the spot, larger prey carried back to the hide and cut up there. No other hunting methods other than high seat hunting were observed. The Somali shrike spears prey and stores supplies.
Behavior and Breeding Biology
The Somali shrike lives singly or in pairs; it is diurnal and safe during the breeding season, but is likely territorial all year round. It is a defensive, aggressive bird that attacks intruders up to the size of a raven and tries to drive them out of their territory.
The breeding season is linked to the respective rainy seasons . Most broods have been observed during the wettest months, when prey is abundant. The breeding season in Ethiopia is in March, between May and August and November, in Somalia it begins on the coast at the end of January and lasts until July in the highlands; fresh nests were also found in November and December. The species breeds in Kenya especially in May and November.
Nest is a rather shallow bowl woven from grass and twigs, which is usually built inside a dense thorn bush at heights between one and one and a half meters. The clutch consists of 3–4 cream-colored, sometimes slightly greenish, pale gray and brownish-spotted eggs at both ends. Further details are not available.
Systematics
The first description of the Somali strangler is a bit confusing, as Gustav Hartlaub called himself the sole author. But the hides of the two birds that Theodor Heuglin hunted near Bender Kam at the beginning of November 1857 were not in front of him, because they were lost in a fight, as Heuglin writes. So he only had the description of Heuglin, on the basis of which Hartlaub recognized them as a new species. Heuglin was only registered as a co-author in 2006.
The relationship of the species within the genus has not been conclusively clarified. The Taitawürger applies due to large morphological similarities sister species, the Lanius collaris - Types circle belongs probably into the next relationship. No subspecies are described.
Persistence and Threat
The species does not appear in any of the IUCN hazard categories. In Somalia it appears to be common in some areas; it is not infrequent in its Ethiopian distribution areas. It is much rarer in Kenya. Only four breeding season observations are available from the southeast of the Republic of South Sudan; It is unknown whether the Somali strangler has only been overlooked there or is generally very rare. The population trend is assessed as stable, and the habitat is hardly threatened either. The Somali shrike breed in some national parks and bird sanctuaries, such as the Awash National Park .
literature
- Tony Harris, Kim Franklin: Shrikes & Bush-Shrikes. Including wood-shrikes, helmet-shrikes, flycather-shrikes, philentomas, batises and wattle-eyes. Christopher Helm, London 2000, ISBN 0-7136-3861-3 .
- Norbert Lefranc, Tim Worfolk: Shrikes. A Guide to the Shrikes of the World. Pica Press, 1997, ISBN 1-4081-3505-1 .
- Reuven Yosef & International Shrike Working Group (2016): Somali Fiscal (Lanius somalicus) . In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/60488 on September 14, 2016).
- Evgenij N. Panov: The True Shrikes (Laniidae) of the World - Ecology, Behavior and Evolution. Pensoft Publishers, Sofia 2011, ISBN 978-954-642-576-8 .
Individual evidence
- ↑ a b c d e f T. Harris, K. Franklin: Shrikes & Bush-Shrikes… 2000, p. 172.
- ↑ a b Lanius somalicus in the IUCN Red List of Threatened Species 2014.3. Posted by: BirdLife International, 2012. Retrieved September 14, 2016.
- ↑ a b c d e Norbert Lefranc, Tim Worfolk: Shrikes. A Guide to the Shrikes of the World. 1997 p. 151
- ^ T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, p. 170.
- ^ A b T. Harris, K. Franklin: Shrikes & Bush-Shrikes ... 2000, p. 171.
- ↑ Recordings at xeno-canto
- ↑ Example with xeno-canto
- ↑ a b c d e f Norbert Lefranc, Tim Worfolk: Shrikes. A Guide to the Shrikes of the World. 1997 p. 152
- ↑ a b c d e Reuven Yosef & International Shrike Working Group (2016): Somali Fiscal (Lanius somalicus) . In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (downloaded from http://www.hbw.com/node/60488 on September 12, 2016).
- ↑ Commentary on the first description
- ↑ Urban Olsson, Per Alström, Lars Svensson, Mansour Aliabadian, Per Sundberg: The Lanius excubitor (Aves, Passeriformes) conundrum — Taxonomic dilemma when molecular and non-molecular data tell different stories In: Molecular Phylogenetics and Evolution. (2010) Vol. 55/2, pp. 347-357.
