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Old Friday 11th March 2011, 18:58  
Richard Klim
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Join Date: Feb 2003
Location: Somerset, UK
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Great Black-backed Gulls breeding at Khniffis Lagoon

Originally Posted by Acrocephalus View Post
Jönsson O. 2011. Great Black-backed Gulls breeding at Khniffis Lagoon, Morocco and the status of Cape Gull in the Western Palearctic. Birding World 24(2): 68-76.
Not the final word. ID-FRONTIERS today...

Norman van Swelm:
according to Olof Jonsson in Birding World 24(2):68-76 just out. In 2009 a presumably full Kelp pair and a mixed pair Kelp Gull L.dominicanus x Atlantic Gull L.atlantis were found nesting after 5-10 Kelp Gulls were seen displaying on the Atlantic coast of southern Morocco.
In 2010 a pair was found breeding at the same spot but surprisingly turned out to be Great Black-backed Gulls L. marinus instead of Kelp Gulls!

The features pro GBBG in the pair are given as: all white tip to P10 and subterminal white spot on P9; the eye looked pale; a red orbital ring; the feet looked pink; tips of inner primaries with rather narrow white tips.

According to the author a true Kelp Gull should show: a mirror only on P10; evenly broad white trailing edge along the inner five primaries; allways dark eyes (quoting Jiquet et al); yellowish-orange orbital ring during breeding and pale yellow outside the breeding season; olive-coloured legs.

The pale colour of the eye is presented as a crucial element in deciding the birds are GBBG's. Apparantly it has escaped this author and others before him that some Kelp populations have pale eyes too! Have a look the various plates in 'Gulls of the Americas' showing pictures of L.d.dominicanus taken in Chile and Argentina and L.d.austrinus from Georgia all with very pale eyes!

Plate 10 in the BW article shows a young bird, said to be a first winter GBBG (photo taken on 18th November). This birds shows very worn tertials and a pattern on the fresh mantle feathers that is quite unusual for birds of that age, compare with pictures here:

all in all a very interesting article but I doubt the last word has been said on the Moroccan gulls. Future visitors to the breeding island are advised to measure the eggs and to collect feathers for DNA analyses.
Cheers, Norman
Lee Evans:

I have just returned from Khenifiss Lagoon in southern Morocco where these large black-backed gulls breed and studied these birds again after initially believing all 10 were Cape (African Kelp) Gulls. Two individuals are fairly typical adult Cape Gulls but the other six adults I recorded were pale-eyed, pinkish or pinkish-grey-legged individuals resembling Great Black-backed Gull. They all appeared to be paired up and were displaying and were present at the island breeding colony shared with Atlantic Yellow-legged Gulls.

This is a unique situation and a very confusing one - Great Black-backed Gull generally breed to the north of Scandinavia in the extreme north but isolated populations such as this have also now been discovered in southern Spain. The birds at Khenifiss Lagoon are clearly resident and breeding and almost certainly intergrading - some individuals share mixed characters

All the very best

Lee Evans
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