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Brown Skua

From Opus

Alternative names: Southern Skua, Subantarctic Skua, Antarctic Skua, Falkland Skua

Adult.  Race S. a. lonnbergi Photo © by Joseph MorlanSalisbury Plain, South Georgia, 5 March 2018
Adult. Race S. a. lonnbergi
Photo © by Joseph Morlan
Salisbury Plain, South Georgia, 5 March 2018
Stercorarius antarcticus

Contents

[edit] Identification

Race S. a. lonnbergi displayingPhoto © by Rodrigo TapiaArdley Peninsula, King George Island, South Shetland Archipelago, Antarctica, January 1992
Race S. a. lonnbergi displaying
Photo © by Rodrigo Tapia
Ardley Peninsula, King George Island, South Shetland Archipelago, Antarctica, January 1992

Size: 52-64 cm (20½-25¼ in), wing 35.5-40.2 cm, wingspan 126-160 cm, females on average are larger in most measurements, most noticeably in wing length.
Nominate subspecies

  • Brown overall plumage, variable from light to dark
  • Pale streaking above
  • Dark cap (often reduced to a mask in light morph birds)

[edit] Variations

Other races are larger, darker and less streaked above. Juveniles uniformly dark.

[edit] Distribution

Circumpolar Subantarctic islands, Antarctic Peninsula, Tristan da Cunha and Gough Islands; Falkland Islands and southern Argentina from Chubut to Tierra del Fuego.

[edit] Taxonomy

This species has been placed in the genus Catharacta with the other large skuas (Sibley & Monroe, 1993; Clements, 2000).

Older texts and some current field guides will treat Brown Skua as a part of Great Skua.

[edit] Subspecies

Nominate racePhoto © by zweiblumenEast Cove, Falkland Islands, 2004
Nominate race
Photo © by zweiblumen
East Cove, Falkland Islands, 2004

There are 3 subspecies[1]:

  • S.a. antarcticus breeds in the Falkland Islands, and south-east South America: Smallest, most heavily streaked.
  • S.a. hamiltoni breeds on Tristan da Cunha and Gough Island: Larger, darker, narrower streaks.
  • S.a. lonnbergi breeds on the Antarctic Peninsula and Subantarctic Islands: Like S. a. hamiltoni but larger.

The subspecies lonnbergi has been treated as a full species Stercorarius lonnbergi by some authorities.[2]

[edit] Habitat

Pelagic. Inland (during breeding season)

[edit] Behaviour

[edit] Breeding

Juvenile.  Race S. a. lonnbergi Photo © by Joseph MorlanSalisbury Plain, South Georgia, 5 March 2018
Juvenile. Race S. a. lonnbergi
Photo © by Joseph Morlan
Salisbury Plain, South Georgia, 5 March 2018

Oct-Nov onwards, on flat grassy areas or short grass heaths. Nest is an unlined or sparsely so, scrape. 1-2 eggs, incubated 28-32 days, young leave nest within 1-2 days and fledge in 40-50 days. Sexual maturity at six years.

[edit] Diet

Scavenger at refuse tips, predates penguin eggs and chicks and burrow nesting seabirds at night.

[edit] References

  1. 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/
  2. Avibase
  3. BF member observations
  4. Handbook of the Birds of the World Alive (retrieved May 2018)

[edit] External Links

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