The gulls at Kniffiss Lagoon (Morocco) are not all Kelp Gulls as presumed before (1 Viewer)

After some observation and nifty photographic skills, we were able to walk away having confidently clinched a pair of Kelp Gulls amongst half a dozen Great Black-backed Gulls; leg colour, structure and restricted white primary mirrors were much more satisfactory than last year when we, along with everybody else, just presumed all were Kelp Gulls.

Click to expand...

Thanks guys - let's hope it spurs the considerable number of WP listers who have been to this site and seen large black-backed gulls (and ticked Cape Gull without really paying much attention) to revisit and see them 'properly'... I for one will hold my hands up and admit that I didn't pay much attention to the 10 birds I saw in April 2009, and am glad I've now consciously identified a couple of Cape Gulls!

Click to expand...

metcow333 said:

dont get birding world

Click to expand...

Acrocephalus said:

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.

Click to expand...

Summary
Since the discovery of four displaying Cape Gulls [Larus dominicanus vetula] in Khniffis Lagoon, Morocco in February 2008, the site has become a popular destination for Western Palearctic birders. The Cape Gulls were apparently residents and the number increased to a maximum of ten adults in April and May 2009, and breeding took place the same year. In May 2010, after analysing photographs of 'Cape Gulls' from the site in April 2010, it was discovered that all the photographed birds from that month were, in fact, Great Black-backed Gulls [L marinus]. An analysis of as many photographs as could be found from the area revealed that only two [ad 20 May 2009, 2 ads 7 Jul 2010], probably three [2 presumed ads 23 Apr 2009], of the records supported by pictures showed Cape Gulls. All the rest either showed Great Black-backed Gulls or were too poor in quality to show which species they portrayed, while one picture [29 Apr 2010] showed an adult apparent hybrid, probably a Yellow-legged [L michahellis] x Great Black-backed or Yellow-legged x Cape Gull. Up to six adult Great Black-backed Gulls were at Khniffis Lagoon during at least February to July 2010, with one pair apparently nesting, while a pair of Cape Gulls were also apparently on territory on the island in Khniffis Lagoon on at least 7th July. In January 2011, birders aware of the situation made thorough searches in the lagoon by boat and found ten Great Black-backed Gulls, but no Cape Gulls.

Click to expand...

Acrocephalus said:

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.

Click to expand...

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 f.i.at 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:
http://www.radioactiverobins.com/gulls/indexlarusmarinus.htm

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

Click to expand...

Norman

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

Click to expand...

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.

Click to expand...

Acrocephalus said:

Norman van Swelm:


Since Norman mentioned measuring eggs, I wonder how easy is the separation of the eggs of these two gulls? Can anyone please check in the relevant literature.

Click to expand...

• Accepted (in this report):
  2009 (09/71) Tarfaya, Khnifiss, 6 adultes et 2 immatures, photo, 18 novembre (K. Olsen et al., Norwegian Ornthological Society)
  
  
• Not accepted (in this report):
  (09/85) Tarfaya, Khnifiss, photos, 4 adultes le 11 décembre, 8 adultes le 14 décembre; (10/14) Tarfaya, Khnifiss, photos, 7 adultes et 1 immature le 21 janvier; 6 adultes le 4 février; 2+ le 13.03 et 6 le 16.03; (10/31) Souss, Oued Souss, adulte, photo, 12 avril.