PORTRAYAL OF A COUNTY CASPIAN

FIELD SKETCHES OF AN ADULT CASPIAN GULL

by Ian McKerchar

On the 11th of February 2007 I found and identified the county's second ever Caspian Gull, this time a full adult, at Heaton Park Reservoir. Unfortunately no photographs of the bird exist (none were taken as far as I'm aware) so I have included my field notes (actually taken at the time of the sighting) in the hope that the scribble and wild sketches within might contribute to forwarding our knowledge of the species at a county level. Please forgive the quality of the artwork, I am much better than this (honest) but it was cold and the hide is dark afterall (two great excuses ☺).

Above: an overall appearance, not brilliant but demonstrating (if you squint a bit!) the overall small headed and long winged appearance. Note the bill is rather small on this individual but still slender and the eye is dark and 'beady', set forward and higher than Herring or Yellow-legged Gull. Note the spacing of the primary extension beyond the tail compared to the distance from the outermost tertial to tip of the tail.        

 Above: trying to get the head shape just right isn't easy and most of these aren't quite just 'there'! Whilst always with a distinct 'concave' forehead the overall profile of the head was most often typically 'pear shaped' and slightly 'snouty' but also in certain positions could appear more rounded (top left sketch). The bill was not particularly long but remarkably parallel sided, appearing as smoothly profiled on the upper edge as the lower, lacking pretty much any significant goyndeal angle, most ably portrayed on the lower most sketch.       

Above: the all-clinching underside of the outer-most primary (P10), seen well if and when you look long and hard enough. The large white mirror (with a very narrow, inconspicuous, almost broken black band near the tip on this individual) and the narrow sharply cut-off black band inside this, combined with the strikingly white tongue on the inner web are all classic pro-Caspian features, but some argentatus Herring Gulls can approach this, laying foundation to the importance in obtaining a full suite of features, checked and double-checked! Note the spacing of the white tip to black subterminal band on P10 and on this individual a small black vertical mark was evident on the lower mandible of the bill just infront of the reddish goyns spot.

Ian Mckerchar, January 2008

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