American Herring Gull (smithsonianus)

(last update: October 30, 2015)

American Herring Gull adult March

The issue of Dutch Birding 26: 151-179, 2004 contained a very comprehensive paper on the identification of adult smithsonianus in a European context, titled: Identification of adult American Herring Gull. It was written by Peter Adriaens & Bruce Mactavish. The outstanding text is copied on this webpage, with links now added to various Canadian and European birds placed on the ORG-website. When appropriate, more details from recent field research has been added as well. Full PDF download: HERE.

Identification of adult American Herring Gull
-Peter Adriaens & Bruce Mactavish-

BACK TO PART 1: INTRODUCTION & GENERAL COMMENTS

BACK TO PART 2: DETAILED PRIMARY DESCRIPTION

P8 (figure 7, table 4-6)

The grey tongue is usually very long, covering more than 3/4 of the visible part of the inner web, and leaving only a rather thin black subterminal band. The tongue on p8 is of approximately the same length as the tongue on P7. On the underside of the wing, the long tongues on P5-P8(P9) leave only a thin and rather straight black trailing edge (cf figure 1b and 2b). In argenteus and many birds of other European forms, the pale tongue is slightly shorter than the one on P7, so the amount of black on the inner web is also larger.

The tongue-tip is often white; some birds have an obviously broad, rounded white spot at the tongue-tip (cf figure 1a and 3), which, together with the white tongue-tip of (P5)P6-P7 may create a ’string of pearls' effect, We did not find an adult argenteus in our sample with such a broad white tongue-tip on P8; in fact, the majority have no white at all here. Among the European forms, the ’string of pearls’ seems to be mostly shown by argentatus, and a few intergrades. Keep in mind, however, that even slightly over-exposed photographs may exaggerate the whiteness of the tongue-tips, and may create the false impression of a broad white spot on the tongue-tip of P8 when there is none. The other extreme is also possible: a more over-exposed photograph can obliterate the white ’string of pearls’.

The shape of the black pattern on the outer web is another important character. Here, and/or on the outer web of P7, many NF smithsonianus have a rather peculiar shape, which we would like to call the ’bayonet pattern' (see figure 7a and 8a). Basically, the pattern consists of a straight or slightly oblique upper border, which then projects towards the primary coverts in a thin, very pointed black wedge (almost ’needle-shaped’) along the outer edge. The shape recalls a French ’bayonet', hence the name. It is important to note the difference with the pattern in figure 7c and 8c: these also show a pointed black wedge towards the primary coverts but it is broader at the base, starting from the shaft and lacking a distinct step. The combination of the three characters mentioned above (’bayonet’, tongue-tip, length of tongue) is significant, as can be seen in figure 7a and the percentages below it.

above: European Herring Gull male 13cy mint 10, Moerdijk, the Netherlands, 05 May 2005 (T. & M. Muusse). Typical argenteus pattern on P10 and P5. The tongue of p10 is thin and pointed. There is a short 'bayonets' on p7 but none on p8, the grey tongue of p8 is slightly shorter than on p7, and lacks a pure white tongue-tip. The white mirror of p9 reaches onto the outer web and the grey tongue is short.
below: European Herring Gull female 14cy mint C0, Moerdijk, the Netherlands, 06 May 2005 (T. & M. Muusse). The tongue of p10 is rectangular and black on P9 limited, not reaching up to primary coverts. Other features wrong for smithsonianus: P5 does not show a complete black band, only a spot on the outer web (no 'W'-shape). The grey tongue of p8 is shorter than on p7, and lacks a white tongue-tip. There are no 'bayonets' on p7-8.

P7 (figure 8, table 6-7)

Basically, the characters to be looked for in P7 are the same as those in P8 but the pale tongue is (nearly) always very long in all forms, and is therefore not helpful. The presence of a ’bayonet' is significant, either on P7 or P8, or on both); see table 5. The amount of white on the tongue-tip should also be noted, although the difference is less obvious than in P8. In some birds, the black colour of the outer web not only projects in a ’bayonet’ or pointed wedge along the outer edge but also slightly along the shaft, thus creating a rather forked or ’V’-shaped pattern (eg, plate 228).

P6 (figure 9)

The shape of the black mark is important. The black band was always complete in our sample of NF smithsonianus (in some birds of European forms, especially in argentatus, there is sometimes only an incomplete black band), and the pattern was usually sharply pointed. It is pointed along the inner edge, along the shaft, and along the outer edge, so that the pattern tends to resemble a sort of drawn out ’W’ (see figure 9a and percentages below it). In quite a few European birds, the black band is clearly broader, lacking the three pointed wedges, and showing an oblique, rounded or straight upper border on the outer web (figure 9b and 9c).

P5 (figure 10, table 8)

The shape of the black mark (when present) is important, even more so than in P6. The majority of NF smithsonianus in our sample had a complete, uninterrupted black band, while this is less frequently seen in European birds. In those NF smithsonlanus with a complete black band, there are normally three pointed wedges (as in P6), creating a nice symmetrical
’W’-pattern (see figure l0a and percentages below it). In birds in which the black band is interrupted, or entirely confined to the outer web, two very pointed wedges usually remain, creating a forked or ’U'-shaped pattern (figure 10b). In argenteus, the common pattern is that of a thick black spot entirely confined to the outer web - which is only rarely seen in NF smithsonianus (see figure 10e). Of those argenteus with a complete black band in our sample, only a minority showed a distinct ’W'-pattern. In argentatus, black markings are commonly absent altogether (figure 10c), No birds in our sample had a distinct, complete ’W’. In Eastern Baltic Herring Gulls, the pattern on P5 is quite variable.

P4

We checked the presence or absence of black marks on this primary, but did not find any significant differences. In all forms that we examined, a variable black mark on the outer web of P4 may occur in a very small proportion of birds (c 2%). In addition, we also found one NF
smithsonianus and one eastern Baltic Herring Gull with an almost complete but thin, black band across both webs.

above: European Herring Gull NLA 5.363.004 male adult, Moerdijk, the Netherlands, 12 July 2005 (T. & M. Muusse). Breeding argenteus, resembling 'northern argentatus'. Note the large white mirror on p9, prominently covering both webs and note absence of 'bayonets' on p7-8.
below: Eastern Baltic Herring Gull Larus argentatus, adult, Wloclawek, Poland, spring 2002 (Grzegorz Neubauer & Magda Zagalska). An example of a European bird with a long, rectangular grey tongue on p10, quite similar to NF smithsonianus. Note, however, the absence of black marks near the tip of p10, and the large white mirror on p9 – obviously covering both webs. There do not seem to be 'bayonets' on p7-8, though the pattern on p8 is partly hidden under p9 here. There are no black marks on p5. Mantle colour can be of additional help: in a sample of 32 Polish European Herring Gulls (caught and ringed), it was perceived as a mean value of 5.63 on the Kodak grey-scale (Grzegorz Neubauer & Magda Zagalska pers comm).

Conclusion: diagnostic combinations

While every marked primary of adult NF smithsonianus is often subtly different from the corresponding one in European forms, there is much variation. It is only when the patterns are combined that they give the wing-tip a unique character. Ideally, all primaries should have a typical pattern, and other characters such as structure (’jizz’), head streaking and bill pattern should look right, but if this is not entirely the case, there are at least two minimal combinations that can be used.
First, a very basic one is the combination of P10 and P5: a pattern as in figure 5a (broad, long, almost rectangular tongue) regularly goes with the pattern of figure 10a (complete black ’W’) in NF smithsonianus (52%), while this exact combination was not found in our samples of
argenteus and argentatus. However, it was present in three Eastern Baltic Herring Gulls (c 4%). In European forms, a long tongue on P10 usually excludes a complete black band on P5; some intergrades argenteus >< argentatus, a few Eastern Baltic Herring Gulls, and a few hybrids argentatus x Pontic Gull do combine this tongue with a complete black band on P5 but the shape of the tongue and the shape of the black band are usually (not always!) different from those in typical NF smithsonianus. Also, check the amount of black between the white mirror and tip of P10; European Herring Gulls with a long, broad tongue here (as in figure 5a) usually show little or no black near the tip - and such birds apparently ’never’ show an uninterrupted black band across both webs. Nevertheless, we would strongly advise to check other characters as well, such as the presence of a ’bayonet’, the extent of white on tongue-tips, and so on.
Second, if the black band on P5 is not complete, identification is more complicated but may still be possible. It should be established that at least all of the following characters are present, before a conclusive identification can be reached: 1 P10 with a long, broad, almost rectangular tongue (as in figure 5a); 2 mirror on P9 confined to inner web, or no mirror at all (figure 6a,c,d; 6a being most typical); 3 ’bayonet’ on either P7 or P8, or on both (figures 7a and/or 8a); 4 white tongue-tip on inner web of P8; at least a thin white crescent but preferably a large, rounded, white spot (figure 7a); and 5 complete black band on P6, which is sharply pointed at least along the outer edge, but preferably also along the shaft and the inner edge (tending towards a ’W’-pattern; cf figure 9a). In our sample of NF smithsonianus, 41% showed the combination of the above five criteria, regardless of their pattern on P5. The same combination was not found in our sample of European forms.
Any potential adult smithsonianus in Europe that does not meet these criteria, should be left unidentified, in our opinion.

European Herring Gull Larus argentatus, adult, Germany, date unknown (Andreas Buchheim). A difficult bird, and therefore a good illustration of why the criteria need to be very strict. Of all the European birds in our samples, this one was closest to meeting the minimal requirements for Newfoundland Herring Gull L smithsonianus. Note, however, that the pattern on p6 is not typical (compare with figure 9; the black band tends more towards pattern 9b than 9a, as it is more asymmetrical – clearly more black on the outer web than on the inner web –, with a distinct 'step' on the shaft, and is less pointed along the outer edge; especially the step on the shaft is wrong for NF smithsonianus).
There are no obvious 'bayonets', only an indistinct one on the outer web of p8. The outer web of p9 is entirely
black all the way up to the primary coverts (note that at least one primary covert is missing at the base). Note also
the disproportionate amount of black on p5: there is a rather thick black spot on the outer web, but nothing on the
inner web. This pattern corresponds with figure 10e, which is shown by only a few NF smithsonianus (2%).

CONTINUE: FINAL COMMENTS

East Coast birds

South Coast birds

birds in Europe