Wednesday, 22 February 2012

Gulls Allowed

Gulls have never been my favourite birds, but I’m starting to like ‘em – mainly because I’m starting to understand them. This is thanks in no small part to Martin Garner (or, as my friend would describe him, “the old man of the gulls”).

On Saturday, I attended one of Martin’s Gull Master Classes at Stubber’s Green boating lake near Walsall. The site is close to a landfill where the gulls feed, and they come to the lake to wash and roost.  It was very windy, very wet, there was hail, and sleet, and just when we didn’t want it, there was bright sunshine - right into our eyes. But, I learnt loads and loads, particularly about juvenile gulls. And, I learnt that I still know next to nothing!

The focus was on the large white-headed gulls – Herring, Caspian, Yellow-legged, Great and Lesser Black-backed, all of which have 4-year-development cycles. We were asked to ignore the 2nd and 3rd-winter birds, and focus in on the juvenile/1st-winter and adult birds. This approached really helped.

Picking out juvenile Herring Gull in flight, from among Great and Lesser-black Backed Gulls instantly became easy. The pale areas of the wings, the tail pattern, the shade of brown in the wings and scapulars, all became recognisable. We also studied the primary wing tips in adults, helping us distinguish between agentatus and argenteus Herring Gull forms, and Caspian and Yellow-legged Gull.

On the deck we picked out a 1st-winter Yellow-legged Gull (see below). Note how the bird has dark wing coverts coverts and tertials, with little pale fringing. Also note the particular patterning on the scapula feathers, making very distinctive when compared to the Herring Gulls present. The birds do not have yellow legs at this stage.

Yellow-legged Gull - Stubber's Green, Walsall, West Midlands, 18th February 2012

The tail, which can’t be seen well here, was also very different. The Yellow-legged has a darker, shorter tail band, with some restricted dark spotting on the white upper-tail coverts. The Herring Gull has a broader, darker tail band, with much barring on the upper-tail coverts.

The clincher was seeing the single, fresh, median covert feather on the Yellow-legged Gull - these birds tend to start their moult early. Being able to ID a young gull with this level of detail was a revelation to me. My confidence is well up now.

We later moved on to Chasewater for the gull roast, finding a 2nd-winter Iceland Gull (pretty obvious that one though), another probable 1st-winter YLG, and a possible immature Caspian Gull.

An excellent introduction to the dark art of gull identification. Now, where’s the nearest landfill to my house?

1 comment:

  1. Sounds like a quality day. Sent you a PM on Birdforum with a proposition for the Yellowthroat on Saturday...!