<strong>Identification</strong> <strong>of</strong> <strong>American</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong> <strong>in</strong> a <strong>western</strong> <strong>European</strong> <strong>context</strong>7374757677 7873 <strong>American</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong> / Amerikaanse Zilvermeeuw Larus smithsonianus, near-adult, Boston, Massachusetts,USA, January 2001 (Pat Lonergan). Note solid-black ‘patch’ on middle tertial and extensive solid-black on primarycoverts.74 <strong>American</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong> / Amerikaanse Zilvermeeuw Larus smithsonianus, adult, Boston, Massachusetts, USA,January 1999 (Pat Lonergan). Similar to bird <strong>in</strong> plate 77 and 83.75 <strong>American</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong> / Amerikaanse Zilvermeeuw Larus smithsonianus, adult, Boston, Massachusetts, USA,February 1999 (Killian Mullarney). Note small tertial-spot on this otherwise apparently ‘full’ adult.76 <strong>American</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong> / Amerikaanse Zilvermeeuw Larus smithsonianus, adult or near-adult, Boston,Massachusetts, USA, January 2001 (Pat Lonergan). Note tertial-spot and black on primary coverts.77 <strong>American</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong> / Amerikaanse Zilvermeeuw Larus smithsonianus, adult or near-adult, Boston,Massachusetts, USA, February 1999 (Killian Mullarney). Note rather blotchy head pattern and f<strong>in</strong>e shaft-streaks onprimary coverts.78 <strong>American</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong> / Amerikaanse Zilvermeeuw Larus smithsonianus, near-adult, Boston, Massachusetts,USA, January 2001 (Pat Lonergan). Note dark <strong>in</strong> primary coverts.28
<strong>Identification</strong> <strong>of</strong> <strong>American</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong> <strong>in</strong> a <strong>western</strong> <strong>European</strong> <strong>context</strong>differences <strong>in</strong> w<strong>in</strong>g-tip pattern between Newfoundlandand Niagara smithsonianus and proposed that thesepopulations represent two dist<strong>in</strong>ct types. In the orig<strong>in</strong>aldraft <strong>of</strong> this paper submitted to the editors <strong>of</strong> DutchBird<strong>in</strong>g we made an attempt to identify potentially usefuldifferences <strong>in</strong> w<strong>in</strong>g-tip pattern between smithsonianusand <strong>European</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong>s. However, aware <strong>of</strong>the fact that long-term studies <strong>of</strong> known-age argenteusand graellsii <strong>in</strong> Brita<strong>in</strong> (Mart<strong>in</strong> Elliott pers comm) <strong>in</strong>dicatethat w<strong>in</strong>g-tip pattern can cont<strong>in</strong>ue to change wellbeyond the po<strong>in</strong>t at which they acquire ‘adult’ plumage,we doubted that any <strong>of</strong> our conclusions on thisparticular aspect <strong>of</strong> smithsonianus identification wouldprove to be <strong>of</strong> much practical value. More recently, webecame aware that a detailed paper on w<strong>in</strong>g-tip patterndifferences between adult smithsonianus and <strong>European</strong><strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong> was be<strong>in</strong>g prepared by Peter Adriaens andBruce Mactavish. We are confident that these authorswill demonstrate the potential usefulness <strong>of</strong> w<strong>in</strong>g-tippattern differences far more successfully than wemanaged to do and we eagerly await publication <strong>of</strong>their f<strong>in</strong>d<strong>in</strong>gs <strong>in</strong> a forthcom<strong>in</strong>g issue <strong>of</strong> Dutch Bird<strong>in</strong>g.Primary coverts A rather high proportion (10-15%) <strong>of</strong>‘adult’ and near-adult birds exhibit dark mark<strong>in</strong>gs on theprimary coverts. These vary from extremely f<strong>in</strong>e blackshaft-streaks (plate 74, 77 and 83) to broader, moreobvious, black lozenge-shaped marks (plate 76, 78 and84). Dark primary-covert-mark<strong>in</strong>gs are sometimesshown by a few adult and <strong>of</strong>ten by near-adult argenteus(Grant 1986) but they tend not to be as well def<strong>in</strong>edand neat, or as black, as <strong>in</strong> many smithsonianus.W<strong>in</strong>ter head-mark<strong>in</strong>gs The pattern <strong>of</strong> w<strong>in</strong>ter headstreak<strong>in</strong>g<strong>in</strong> adults and near-adults <strong>of</strong>ten appears different<strong>in</strong> smithsonianus – be<strong>in</strong>g blotchier with less well-def<strong>in</strong>edstreaks than <strong>in</strong> argentatus/argenteus (plate 74, 77 and83). However, as with many <strong>of</strong> the other features, this isvariable and should be used with caution.Bill pattern A high proportion <strong>of</strong> the near-adult smithsonianuswe studied <strong>in</strong> Massachusetts <strong>in</strong> January-February had more extensive blackish mark<strong>in</strong>gs aroundthe gonydeal area <strong>of</strong> one or both mandibles than weare used to see<strong>in</strong>g <strong>in</strong> <strong>European</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong>s at thesame time <strong>of</strong> year. Dark mark<strong>in</strong>gs on the bill <strong>in</strong> all <strong>of</strong>these large gulls are l<strong>in</strong>ked with both immaturity andwith season (with adults develop<strong>in</strong>g a dark spot <strong>in</strong> w<strong>in</strong>ter),so their significance <strong>in</strong> the <strong>context</strong> <strong>of</strong> identify<strong>in</strong>g avagrant <strong>in</strong> Europe is doubtful.VoiceWhile at this stage we do not anticipate voicecharacteristics hav<strong>in</strong>g a major bear<strong>in</strong>g on theidentification <strong>of</strong> vagrants, we have registered adist<strong>in</strong>ctly deeper tone, and possibly a subtly differentrepertoire compared with argenteus withwhich we are most familiar. Whether this is primarilya function <strong>of</strong> body size and whether thedifferences are as pronounced <strong>in</strong> comparisonwith argentatus is unclear and requires furtherresearch.HybridsWhile ‘larophiles’ on the West Coast <strong>of</strong> NorthAmerica have had to make sense <strong>of</strong> an extraord<strong>in</strong>aryvariety <strong>of</strong> hybrid gulls for many years,and have now ga<strong>in</strong>ed sufficient confidence to beable to guess the parentage <strong>of</strong> many <strong>of</strong> them,their equivalent <strong>in</strong> Europe is lagg<strong>in</strong>g beh<strong>in</strong>d <strong>in</strong>this particular field. With presumed hybridsapparently be<strong>in</strong>g <strong>of</strong> much more exceptionaloccurrence <strong>in</strong> Europe than on the West coast <strong>of</strong>North America it is difficult for any <strong>in</strong>dividual toga<strong>in</strong> a broad enough perspective on the problemto beg<strong>in</strong> to make sense <strong>of</strong> it. The extent to whichhybrid gulls <strong>in</strong> Europe may be complicat<strong>in</strong>g ourattempts to identify smithsonianus on this side <strong>of</strong>the Atlantic can only be guessed at, and until wehave a clearer understand<strong>in</strong>g <strong>of</strong> the limits <strong>of</strong>variation with<strong>in</strong> ‘pure’ smithsonianus it is likelyto rema<strong>in</strong> so.Some first-w<strong>in</strong>ter and second-w<strong>in</strong>ter presumedhybrids Glaucous x <strong>European</strong> <strong>Herr<strong>in</strong>g</strong> <strong>Gull</strong> beara strong superficial resemblance to smithsonianus,especially when their mix <strong>of</strong> characterscomb<strong>in</strong>es the size, rather uniform plumage, billcolouration and general demeanour <strong>of</strong> Glaucouswith the dark w<strong>in</strong>g-tip and tail pattern <strong>of</strong><strong>European</strong> <strong>Herr<strong>in</strong>g</strong>. Most, however, possessobvious clues <strong>in</strong> their appearance to their hybridorig<strong>in</strong>, such as a much reduced or washed-outtail-band and secondary-bar, obvious pale fr<strong>in</strong>gesto the primary-tips or, at rest, a lighter overalltone to the tertials than a typical <strong>European</strong><strong>Herr<strong>in</strong>g</strong>; others, however are not so obvious andcorrect identification may require very criticalconsideration <strong>in</strong>deed. In North America, hybridsGlaucous x smithsonianus (so-called ‘Nelson’s<strong>Gull</strong>’) occur; these are usually more similar toGlaucous than to smithsonianus (Bruce Mactavish<strong>in</strong> litt) but there is evidence that differentpopulations <strong>of</strong> smithsonianus and Glaucous producedifferent look<strong>in</strong>g hybrids, some <strong>of</strong> whichlook more like pale smithsonianus but with lowcontrast between tertials and folded primariesand rest <strong>of</strong> upperparts (Bruce Mactavish <strong>in</strong> litt).At least two birds believed to be second-w<strong>in</strong>tersmithsonianus recorded <strong>in</strong> Ireland were <strong>in</strong>itiallythought to be hybrids Glaucous x <strong>European</strong><strong>Herr<strong>in</strong>g</strong> until more detailed exam<strong>in</strong>ation <strong>in</strong>dicatedthat their Glaucous-like character was quitecompatible with typical second-w<strong>in</strong>ter smithsonianus.ConclusionWith a total <strong>of</strong> around 70 accepted or likely to beaccepted records <strong>of</strong> smithsonianus <strong>in</strong> Europe29