by Ted Rogers
25th January 2004
I vaguely remember a time when all white birds I saw anywhere near the sea were seagulls. Some time later, with a little knowledge gleaned from my Observers Book of Birds, I realised that not all seagulls were the same and so adopted the generic name of gulls, although still struggled to tell one species from another. Equipped with better field guides and a little more experience I started to differentiate between Black Headed Gulls, Common Gulls, Herring Gulls and the like with a degree of confidence, although, with a fair proportion of all these gulls being in various stages of juvenile development, it was never easy. Now just when I thought I was getting a real grasp of things, I learn that there are also a number of sub-species, some of which seem to be heading towards full species status. For me, all large, pale grey winged gulls with black wing tips with white mirrors were Herring Gulls, but as anyone who attended the ROC Gull Identification evening last December will know, not all Herring Gulls are the same. For a start even the genuine Herring Gull consists of a number of sub-species, with the argenteus and argentatus being most often found in the UK. The similar but clearly different Yellow Legged Gull (or Yellow Legged Herring Gull as it used to be called!) is a separate species that I first came across on continental birding trips (but could only identify if it was well mannered enough to 'show a leg'). It doesn't stop there however - even the Yellow Legged Gull comes in different forms. The ever playful (or so the jizz experts will tell you) Caspian Gull is a variant which may soon achieve species status - it is distinguished by its elongated profile, longer wings and other subtler plumage features. Now you may think that there is not too much to remember here, but don't forget that Herring Gulls and other large gulls take at least three years to acquire adult plumage, leaving endless variations in juvenile plumage, along with differences between summer and winter plumages to contend with as well!
And so it was, brimming with all this new information, that a select few ROC members met up with gull expert Paul Bright Thomas in the car park at Farmoor Reservoir on the chosen Sunday afternoon. Afternoons are good times for winter gull watching as the birds return to the roost sites later in the day. Although the trip was set for late January, the feeling was that slightly earlier in the winter is better for spotting gulls such as Yellow Legged and Caspian as they acquire summer plumage (i.e. white heads) earlier than other Herring Gulls and hence are easier to pick out in a crowd when they have white heads and the Herring Gulls don't. We quickly moved on to the Dix Pit where we met up with our local expert Ian Lewington and soon picked out and identified a number of juvenile and adult Herring and Lesser Black Backed Gulls. We also picked out one Herring Gull that had even the experts puzzled (a fact that gave me some pleasure as I was struggling with the easier ones!). Leaving the mystery bird aside we moved on to some other likely pits in the area, where we quickly spotted an adult gull with a long bill, extended head shape, long wings and pale grey mantle endlessly splashing and preening on the lake. Surely this must be one of those playful Caspian Gulls, a suspicion that was confirmed by our expert leader (and we of course believed him!). Certainly the bird was quite distinctive, but whether I would have the confidence to pick out another unaided I have my doubts.
We then headed back to Farmoor in time for gulls arriving into the roost and were able to pick out a few Yellow Gulls in the descending gloom, their white heads and slightly darker mantles showing quite well even in the poor light. No other interesting gulls were located (we could not possibly have missed the immature Glaucous Gull which was reported the following day, could we?). As the light failed we headed back to the car park, looking back on a very interesting afternoon, gaining an insight into this somewhat specialised aspect of bird watching. Many thanks go to Paul Bright Thomas and Ian Lewington for sharing their considerable knowledge with us. Now, what was that gull we found on Dix Pit ?