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'''Alternative name: Long-tailed Skua''' | '''Alternative name: Long-tailed Skua''' | ||
| − | [[Image: | + | [[Image:Long tailed Skua.jpg|thumb|550px|right|''S. l. longicaudus'', adult <br />Photo by {{user|NIGHTJAR1|NIGHTJAR1}}<br />[[Svalbard (Spitzbergen)|Spitzbergen]], [[Norway]], June 2007]] |
;[[:Category:Stercorarius|Stercorarius]] longicaudus | ;[[:Category:Stercorarius|Stercorarius]] longicaudus | ||
==Identification== | ==Identification== | ||
| − | + | Length 50–55 cm (including tail projection of 12–24 cm), wingspan 105–112 cm, weight 230–350 g<br /> | |
| + | [[Image:Stercorarius-longicaudus_by_Kudryavtsev.jpg|thumb|350px|right|''S. l. longicaudus'', adult in flight<br />Photo by {{user|Kudryavtsev|Kudryavtsev}} <br />Location: Yamal, [[Russia]], June 2006 ]] | ||
'''Adult'''<br /> | '''Adult'''<br /> | ||
| − | * | + | *The smallest, and often the scarcest skua |
| − | * | + | *Light grey-brown upperparts |
| − | * | + | *Creamy white breast, with yellow flush on throat and cheeks |
| − | * | + | *Grey belly |
*Black cap (which covers eyes and chin and ends at yellow nape | *Black cap (which covers eyes and chin and ends at yellow nape | ||
| − | *Upperwings | + | *Upperwings dark-edged |
| − | * | + | *Primaries blackish, except for white ''shaft'' only on outermost two primaries |
| − | *Blue- | + | *Dark grey tail with black edges and very long, ''flexible'' black streamers |
| − | Sexes similar<br /> | + | *Blue-grey legs with webbed feet |
| − | '''Juvenile''' is heavily barred and spotted | + | *Bill black; short and stubby compared to other skuas |
| − | + | *Sexes similar<br /> | |
| + | '''Juvenile''' has much shorter tail streamers than adult, but still longer than those of other juvenile skuas; streamer tips broad, ''rounded''. Bill grey with a dark tip. Three morphs, varying in darkness:<br /> | ||
| + | *Pale morph is extensively pale grey, often with a nearly white head; only flight feathers (primaries, secondaries, retrices) dark | ||
| + | *Intermediate morph is heavily barred and spotted grey with white patches on underwings, white throat, white belly | ||
| + | *Dark morph juvenile is much darker overall, with grey throat, and without white belly; only a few pale bars on under-tail coverts | ||
==Distribution== | ==Distribution== | ||
| − | [[ | + | Breeds on arctic tundra of far northern areas from northern [[Europe]] ([[Norway]] eastwards), through most of arctic [[Asia]], and [[Alaska]], northern [[Canada]], and [[Greenland]]. Migration usually well offshore, but can be seen in good numbers at a few oceanic headlands, such as Ard an Runair on [[North Uist]], [[Scotland]]. Winters at sea, primarily between 50–60°S latitude, south of the coasts of [[South Africa]], southern [[South America]] and [[Australia]] and [[New Zealand]]<sup>[[#References|[2]]]</sup>. |
| − | + | ==Taxonomy== | |
| + | Two subspecies are recognised<sup>[[#References|[1]]]</sup>: | ||
| + | * ''S. l. longicaudus'' | ||
| + | :*Breeds far northern [[Europe]] and western [[Siberia]] | ||
| + | * ''S. l. pallescens'' | ||
| + | :*Breeds northern North America and northeastern Asia (white-headed juveniles are more common in this subspecies). | ||
| − | |||
| − | |||
| − | |||
==Habitat== | ==Habitat== | ||
| − | Nests on Arctic tundra. Spends winters over open ocean mainly near upwelling zones at the edge of the continental shelfs, usually staying offshore, and very rarely found inland. However, in migration, and especially in central and northern Europe, a juvenile skua found inland on | + | Nests on Arctic tundra. Spends winters over open ocean mainly near upwelling zones at the edge of the continental shelfs, usually staying offshore, and very rarely found inland. However, in migration, and especially in central and northern Europe, a juvenile skua found inland on barren tundra should be considered a Long-tailed until proven otherwise. |
==Behaviour== | ==Behaviour== | ||
| − | [[Image:Long tailed skua juv.jpg|thumb|350px|right|Photo by {{user|scottishdude|scottishdude }}<br /> | + | [[Image:Long tailed skua juv.jpg|thumb|350px|right|''S. l. longicaudus'' juvenile, dark morph<br />Photo by {{user|scottishdude|scottishdude }}<br />at Shelford, [[:Category:Nottinghamshire|Nottingham]], [[UK]]]] |
====Breeding==== | ====Breeding==== | ||
Breeding is reliant upon the availability of lemmings, its principal summer food, in almost the entire breeding range. | Breeding is reliant upon the availability of lemmings, its principal summer food, in almost the entire breeding range. | ||
| Line 34: | Line 41: | ||
==References== | ==References== | ||
| − | # | + | #{{Ref-Clements6thAug17}}#{{Ref-HBWVol3}} |
| − | |||
| − | # | ||
| − | |||
#Collins Field Guide 5th Edition | #Collins Field Guide 5th Edition | ||
#[http://www.birdforum.net/showthread.php?p=1590497 Birdforum thread] discussing id of a dark juvenile | #[http://www.birdforum.net/showthread.php?p=1590497 Birdforum thread] discussing id of a dark juvenile | ||
Revision as of 15:29, 2 October 2017
Alternative name: Long-tailed Skua
- Stercorarius longicaudus
Identification
Length 50–55 cm (including tail projection of 12–24 cm), wingspan 105–112 cm, weight 230–350 g
Adult
- The smallest, and often the scarcest skua
- Light grey-brown upperparts
- Creamy white breast, with yellow flush on throat and cheeks
- Grey belly
- Black cap (which covers eyes and chin and ends at yellow nape
- Upperwings dark-edged
- Primaries blackish, except for white shaft only on outermost two primaries
- Dark grey tail with black edges and very long, flexible black streamers
- Blue-grey legs with webbed feet
- Bill black; short and stubby compared to other skuas
- Sexes similar
Juvenile has much shorter tail streamers than adult, but still longer than those of other juvenile skuas; streamer tips broad, rounded. Bill grey with a dark tip. Three morphs, varying in darkness:
- Pale morph is extensively pale grey, often with a nearly white head; only flight feathers (primaries, secondaries, retrices) dark
- Intermediate morph is heavily barred and spotted grey with white patches on underwings, white throat, white belly
- Dark morph juvenile is much darker overall, with grey throat, and without white belly; only a few pale bars on under-tail coverts
Distribution
Breeds on arctic tundra of far northern areas from northern Europe (Norway eastwards), through most of arctic Asia, and Alaska, northern Canada, and Greenland. Migration usually well offshore, but can be seen in good numbers at a few oceanic headlands, such as Ard an Runair on North Uist, Scotland. Winters at sea, primarily between 50–60°S latitude, south of the coasts of South Africa, southern South America and Australia and New Zealand[2].
Taxonomy
Two subspecies are recognised[1]:
- S. l. longicaudus
- S. l. pallescens
- Breeds northern North America and northeastern Asia (white-headed juveniles are more common in this subspecies).
Habitat
Nests on Arctic tundra. Spends winters over open ocean mainly near upwelling zones at the edge of the continental shelfs, usually staying offshore, and very rarely found inland. However, in migration, and especially in central and northern Europe, a juvenile skua found inland on barren tundra should be considered a Long-tailed until proven otherwise.
Behaviour
Breeding
Breeding is reliant upon the availability of lemmings, its principal summer food, in almost the entire breeding range.
Vocalisation
<flashmp3>Stercorarius longicaudus (song).mp3</flashmp3>
Listen in an external program
References
- Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2017. The eBird/Clements checklist of birds of the world: v2017, with updates to August 2017. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
- Del Hoyo, J, A Elliot, and J Sargatal, eds. 1996. Handbook of the Birds of the World. Volume 3: Hoatzin to Auks. Barcelona: Lynx Edicions. ISBN 978-8487334207
- Collins Field Guide 5th Edition
- Birdforum thread discussing id of a dark juvenile
Recommended Citation
- BirdForum Opus contributors. (2024) Long-tailed Jaeger. In: BirdForum, the forum for wild birds and birding. Retrieved 6 May 2024 from https://www.birdforum.net/opus/Long-tailed_Jaeger
