Yellow PDHN & PDUS = Larus cachinnans kolonia

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Klaas van Dijk
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Joined:Wed Dec 16, 2009 8:32 pm
Yellow PDHN & PDUS = Larus cachinnans kolonia

Post by Klaas van Dijk » Fri Oct 22, 2010 10:39 am

Recently, 2 colour-ringed gulls from a mixed colony in SW Poland were observed in the northern parts of The Netherlands. Both observations were ring readings of healthy birds. The official ring recovery report from the Polish Ringing Centre ('Ornitological Station Museum and Institute of Zoology PAS') gives both a species name hitherto unknown to me:

species = Caspian Gull Colony Larus cachinnans kolonia.

Both were ringed as a chick on 27 May 2010 on 50.29N,16.58E (site is called 'ZB. Kozielno, Paczków, Opolskie, Poland' on the recovery report).
Yellow PDHN (Gdansk DN 18606) was seen on 10 August 2010 in the Eemshaven (53.27N, 06.53E) by Dick Veenendaal.
Yellow PDUS (Gdansk DN 18723) was seen on 10 September 2010 at the island Schiermonnikoog (53.28N, 06.10E) by Holmer Vonk.

Greetings,

Klaas van Dijk / Groningen / The Netherlands.

Ruud Altenburg
Posts:248
Joined:Sun Sep 27, 2009 1:58 pm

Re: Yellow PDHN & PDUS = Larus cachinnans kolonia

Post by Ruud Altenburg » Fri Oct 22, 2010 6:44 pm

I don't know exactly what your point is Klaas but PDHN was photographed by Frank van der Meer in Den Haag on 19-10-10. It looks like a text book cachinnans to me, what a beauty!
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michal rycak
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Re: Yellow PDHN & PDUS = Larus cachinnans kolonia

Post by michal rycak » Mon Oct 25, 2010 10:52 am

Hi Klaas!
Definition taken from Polish Ringing Centre - Instructions of wild birds ringing:
Larus cachinnans kolonia - accurate taxonomic of both parents is unknown, pullus was ringed in gulls colony with visible predominance adult birds with features of L. cachinnans.

I hope that definition helps you to better understand sense of that type of species name :)


All the best,
Michal

Klaas van Dijk
Posts:9
Joined:Wed Dec 16, 2009 8:32 pm

Re: Yellow PDHN & PDUS = Larus cachinnans kolonia

Post by Klaas van Dijk » Fri Dec 03, 2010 11:41 am

hi Michal,

Thanks for your explanation and please excuse me for the delay of my reply. I think it is a good descision of the Polish Ringing Centre to use this kind of names for gulls breeding in a mixed gull colony where Herring Gull and Caspian Gull both are breeding, and where a variety of hybrids or intermediates occur as well.

In the meanwhile I have read the very interesting paper on assortative mating in one of these mixed colonies in Poland (Grzegorz Neubauer and co-workers, The Auk 126 [2009], page 409-419). It was striking to read that all breeding adults that were trapped on the nest could only be safely identified as either argentatus or cachinnans or intermediate after performing a Principal Component Analysis on 6 different variables that had been measured on the birds in the hand.


Furtheron, green 86P1 was also recently observed in The Netherlands. It turned out to be a chick born in 2006 in the mixed colony Wloclawek Reservoir, the mixed colony where the research on assortative mating was carried out. The colour-ring was read on 16 November 2010 in the harbour of Lauwersoog, and the observer identified it as a Caspian Gull. The bird is named Larus argentatus colony and has a mother that is an argentatus-looking bird. Grzegorz Neubauer wrote that they had identified it as a cachinnans on 18 April 2009, when green 86P1 was seen in the natal colony.

Best wishes,

Klaas van Dijk

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