Monday 27 April 2015

2nd year Yellow-legged Gull

26th April 2015 - Topsham


As you may have noticed, I like to pop down to Topsham Recreation Ground on an afternoon to look at the gulls. Sometimes I take my scope, sometimes I take my dog, rarely both at the time. Today I took the dog. This inevitably put a slightly different perspective on my gull watching, harder to see details but general impressions are more obvious perhaps. It turned out to be my most interesting/rewarding session in months (this is clearly not saying much - it's been dire). I found my first genuine Yellow-legged Gull of the year.

This is not a plumage I'm particularly familiar with, most michahellis I see are fresh 1st year birds in late summer. Although this bird's wings are still essentially 1st year, ongoing body and scapular moult has changed its appearance considerably from what it would have looked like last August. It took me a few minutes to see enough of the wings and particularly the tail to convince myself. The grey mantle feathers might suggest a 2nd winter/3rd cal yr bird in argenteus but michahellis is more advanced in these things. The wings don't lie, however, and are clearly mostly 1st generation feathers - though still fairly unbleached and unworn suggesting this bird hasn't wintered too far south.

Yellow-legged Gull 2nd cal yr - 26/4/2015 Topsham
 The classic 1st year mick tail pattern looks like nothing shown by a Herring Gull. The first thing I noticed.

Yellow-legged Gull 2nd cal yr - 26/4/2015 Topsham
 Dark underwing coverts, and the breast sides and flanks are fairly neatly marked with spots or chevrons on white background, typically dirtier, more smudged and blotchy in Herring Gull.

Yellow-legged Gull 2nd cal yr - 26/4/2015 Topsham
 The wing is still mostly juvenile with a few inner coverts at least replaced. The coverts are basically dark-centred with little obvious barring typical of michahellis. Primary moult has already started with P1 and 2 dropped, a little more advanced than argenteus.

Yellow-legged Gull 2nd cal yr - 26/4/2015 Topsham

Yellow-legged Gull 2nd cal yr - 26/4/2015 Topsham

Yellow-legged Gull 2nd cal yr - 26/4/2015 Topsham 

Less obvious when sat or standing perhaps but still looking subtly different from the other 2nd years. The combination of dark 1st generation (mostly) wings with the rather 2nd winter like mantle is slightly incongruous. Those plainer greyish scapulars are presumably 3rd generation feathers.

A note on age terminology: this bird hatched and fledged last summer and is approaching its 1st birthday, so it's in its 2nd calendar year (2nd year would be appropriate). As we're in late April it could be called either 1st winter or 2nd summer (1st spring never seems to get used). In terms of moult, it's started primary moult so is now a 2nd cycle bird - those 2nd generation P1 & 2 are there, they just haven't grown long enough to be seen yet.

Many thanks to Martin Elliott for the helpful discussion.

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