Olrog's Gull - BirdForum Opus

Larus atlanticus

File:AdultOrlog'sGullRenato.jpg

Adult/
Photo by Renato
Tavares/RS,Brasil

Larus atlanticus

Subadult
Photo by Fritz73
Mar del Plata, Buenos Aires, Argentina

Identification

Length 50-56 cm, wingspan 130-140 cm, weight 900-960 g

• Adult: white head, neck, rump and underside, black wings with broad white trailing edge, black band on tail, bright yellow legs, yellow bill with a black band near the end, and red tip. Head smudged grey-brown in winter.
• Subadult: much as adult, but varying amount of brown retained on wings, no red tip on bill, and legs pinkish-yellow.
• Juvenile: mostly brown overall, with black tail and whiter face and undertail; bill dull yellow with black tip; legs pinkish-yellow.

Similar species

Averages smaller than Kelp Gull, though largest Olrog's just overlap with smallest Kelp, and has black band on tail at all ages. Very similar to Belcher's Gull but does not overlap in range; differs in sharply demarcated edge of white to black on the nape and back (graded grey tones in Belcher's).

Distribution

Breeds on the Atlantic Ocean coast of Argentina, from 38°S to 45°S. Nonbreeding (winter) range includes the coast north to Uruguay and southernmost Brazil.¹

Taxonomy

Monotypic. Closely related to Belcher's Gull from the Pacific coast of South America, and first described as a subspecies of it though now universally treated as a separate species².

Habitat

Flat, sandy islands, beaches, rocky coasts, harbours, coastal and brackish lagoons and estuaries.

Status

Total population small, only around 7,000 pairs, now stable with better protection after a historical decline. Upgraded from Vulnerable to Near Threatened in the IUCN Red List.¹

Behaviour

Eggs are laid in September-October and chicks fledge in November.

The diet includes mainly of crabs in the breeding season, taken on tidal mudflats; also takes some shellfish and small fish. Unlike Belcher's Gull and Kelp Gull, does not normally scavenge for carrion or take seabirds².

References

1. BirdLife International Species factsheet: Larus atlanticus. Downloaded from http://www.birdlife.org on 12/12/2014.
2. 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

• List of references

Recommended Citation

• BirdForum Opus contributors. (2024) Olrog's Gull. In: BirdForum, the forum for wild birds and birding. Retrieved 8 May 2024 from https://www.birdforum.net/opus/Olrog%27s_Gull

External Links

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