Monday 11 August 2014

More on Caspian Gull PADZ

Steve Lister has kindly reminded me that he saw PADZ at Albion landfill site in December 2013 and February 2014 (see chart below). He had commented on his first sighting that it was a typical Caspian Gull apart from its legs, which were shorter than normal. I saw it out of the water standing next to a Lesser Black-backed Gull, which had obviously shorter legs. I considered PADZ's legs to be moderately long rather than short or long.

Adult Caspian Gull (PADZ)

Primary Pattern of PADZ

Using the trait scoring chart that was in BB (also here), I scored it as follows.

P10 overall pattern: white to black ratio, score 0, less black than white
P10: white tip, score 0, clear white
P10: tongue, score 0, whitish or pale grey tongue
P5: extent of black, score 1, black on both webs connected, forming band, black on outer web deeper than inner
P4: extent of black, score 2, no black
Iris peppering, score 1, moderately dark
Eye ring colour, score 1, not seen so scored it average
Bill shape, score 1, slim, slight gonydeal angle (within ratio 2.4-2.79) 
Leg length, score 1, moderately long

Total: 7

This falls within the range of a pure Caspian Gull. Most of the traits shown by this individual are the most common shown by the pure Caspian Gulls sampled. The eye colour might warrant another point as it was difficult to asses, but examining the zoomed up photographs I can see the eyes are obviously darker than typical adult Herring Gulls. 

Below is a copy of the sightings of PADZ so far, which was provided by the Polish Bird Ringing Centre.

Sightings of Caspian Gull PADZ
Map of Sightings for PADZ

The map clearly shows the westward movement that this gull makes during autumn and winter. It is surprising that there are no sightings from the London area - keep a look out boys.

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