Heuglin's Gull (L. heuglini / antelius)

(last update: 6-3-2011)

3cy heuglini: August

P10 tips: Type 1-5. Note that a 'mirror' is defined as spot on a web, hence P10 has '2 mirrors' in Typ 1 - Type 4, and '1 mirror' in Type 5.

table 2 (Buzun, 2002): Classification of wingtip pattern types of 'West Siberian Gull' Larus heuglini antelius from the Russkii Zavorot peninsula and the Gulf of Ob, Russia.
Locality	Primary	No.	% Type 1	% Type 2	% Type 3	% Type 4	% Type 5
Russkii Zavorot	P10	38	2.6	51.3	23.1	15.4	7.7
.	P9	38	0	5.3	21.1	73.7	0
Ob	P10	17	0	84.0	11.0	5.0	0
.	P9	17	0	0	26.0	74.0	0
Notes: Typological scheme for recording wingtip patterns of 'dark-mantled' gulls: P10 Type 1: Two large, open mirrors; distal mirror connected with white tip of the feather. Type 2: Large outer open mirrors; white tips discernible. Type 3: Mirror closed (surrounded by black) on outer web; white tips not present, or present on outer web only. Type 4: Mirrors closed on both webs. Type 5: Only one closed mirror (often on inner web). P9 Type 1: Two large mirrors (but always smaller than those on P10); outer mirror frequently not entirely surrounded by black (open). Type 2: Small, closed mirrors. Type 3: Closed (or, less often, open-ended) mirror on only one web. Type 4: No mirrors present.

P9 tips: Type 1-4.

Below you will find a copy of Descriptive update on gull taxonomy: 'West Siberian Gull', by Valery A. Buzun published in British Birds 95 • May 2002 • 216-232. Most of the text below is a copy of that article, but now illustrated with many more birds and figures, and additional data from Dutch samples.

"I" in the text below refers to the original author Buzun. If any errors occur in this text, please let me know and mail to marsmuusseatgmaildotcom.

PART 1 - INTRO & MANTLE COLOUR
PART 2 - PRIMARY PATTERN & BARE PART COLORATION
PART 3 - MORPHOMETRIC & DIMORPHISM
PART 4 - BODY SIZE
PART 5 - PRIMARY MOULT
PART 6 - GEOGRAPHICAL VARIATION

Descriptive update on gull taxonomy: 'West Siberian Gull' - Valery A. Buzun

PART 2

Fig. 1. The most common wingtip pattern of ‘West Siberian Gull’ Larus heuglini antelius. Measurements (a, b, c) used to quantify the extent of the black pigment on P10 and P9 are shown. The size ‘b’ on P9 is the same as on P10. Maximum lengths are measured for white subterminal ‘mirrors’. The basal grey portion of P10 is usually lighter than represented here.

Primary pattern
There is extensive black in the primaries of antelius, as with the rest of the group of slaty-mantled gulls. About 5% of individuals show black in only the six outer primaries; the rest show black in seven or eight primaries (the proportions of each type are approximately equal). The results of my classification of the wingtip pattern of antelius from two sites within the breeding range are presented in table 2 (above). A sample of the most common type of pattern is given in fig. 1 (see right).
Although antelius shows more black in the outer primaries than do the other slaty-mantled gulls, it also has extensive white mirrors on the outermost primary (P10). About 50% of individuals possess a shadowy grey patch encompassing between a quarter and one-sixth of the total area of the mirror on the internal web of P10. Typically, mirrors are smaller or absent on P9: approximately 30% of individuals have one mirror on the outer web, and 8% have small mirrors on both webs of P9 (table 3). The white tip of P10 is reduced; 63% of individuals have a white tip on the external web only, and 24% have no white tips at all.

Importantly, antelius shows one feature which is much more completely developed in 'Caspian Gull' L. cachinnans cachinnans: a white or off-white base of the primaries. Although it is not so obvious as the white ‘tongues’ on the primaries of many cachinnans (Garner & Quinn 1997), 70-75% of antelius have a white or whitish base of the internal web of P10; in 25-30% of individuals, this base is grey. (It is impossible to give the exact proportion of birds with a grey or a white basal area of P10 because of the difficulty of discerning shades of very pale grey.) The base of the inner web of P9 is normally grey, but on a very small number of individuals it may be grey-white (in comparison with the grey base of P8).
It is usually possible to determine a distinct border between the basal grey and distal black portions of P10, although this is not the case with about 5% of individuals. The shape of this border is largely straight, as in armenicus, and is not concave or convex (fig. 1).

Fig. 2. On P8, black on outerweb reaches primary coverts.

The basal grey portion of the primaries of antelius is the least extensive of those of all members of the large white-headed gull complex. Moving descendently from P10 in the half-open wing, the grey portion of the outer web first becomes visible (projecting beyond the tips of the primary coverts) between P7 and P5 on 55-60% of individuals, whereas in all other forms (except nominate fuscus) it is seen on P8-P9 (fig. 2). The grey base of the primaries is evident from P6-P7 in about 15% of armenicus. In heuglini, the grey primary bases are usually visible on P8-P9; on only about 5% of birds is the grey first apparent on P7. Consequently, about 50% of antelius, with very restricted grey in the primaries, can be confidently distinguished in the hand from heuglini on the basis of this feature.
Stegmann (1934) asserted that antelius always possesses black subterminal pigment in P4, and frequently also in P3, a statement confirmed by Devillers (1983).
In summary, antelius shows the most extensive development of black pigmentation in the primaries within the large white-headed gull complex, with the exception of fuscus. This is evident not only in the number of primaries with black subterminal bands, but also in the percentage extent of black across the primaries.

Lesser Black-backed Gull 7L graellsii 8CY male, May 09 2006, Moerdijk, The Netherlands (Theo Muusse). No Mirror on P9, open mirrors on P10 with full subterminal band. This is the common pattern for adult antelius in Buzun's research. It was also the most common pattern at Moerdijk, the Netherlands, with 39% of the population showing this combination. Note also here: black on the outerweb of P8 reaches primary coverts, P7 first primary to show grey on outerweb.

Lesser Black-backed Gull AZ graellsii 10CY female, May 05 2005, Moerdijk, The Netherlands (Mars Muusse). Pale underside of P10 only fractional darker than white primary coverts.

{Additional data graellsii. Buzun describes the pale underside of P10 as 'white' based in most birds. At Moerdijk, this is not common, most of the birds have the base of the underwing of P10 'grey', 'silvery' of 'pale greyish' coloured. Rough estimation would be: white base on the underside of P10 in Russia: 70-75%, for Moerdijk: 1-3%.
Drawing a sharp division between white and grey is difficult, with all kinds of shades in between. At Moerdijk a 'silvery grey' base of the underwing of P10 is common, but we consider this still not to be white. Maybe best would be a direct comparison with the pure white greater primary coverts on the underwing, where they meet the base of P10. Two example birds above and below, coming close to white undersides of P10.

Lesser Black-backed Gull V1 graellsii female, May 21 2005, Moerdijk, The Netherlands (Theo Muusse). Pale underside of P10 only fractional darker than white primary coverts.

Seasonal problem at Moerdijk: wing-tip of LBBG oTL doesn't allow firm statements about exact pattern of P10-P9. The image above illustrates the problem when scoring wing-tips in May in the Netherlands. Another problem are the differences in scoring classes between Valery's heuglini and our graellsii.

The pies below show the distribution and classification for P10 (n=931) and P9 (n=929) we have used at Moerdijk (remember that Dutch LBBG show no significant difference between sexes for either the P10 or P9 patterns).

And the pies below show the distribution and classification for P10 and P9 used by Valery. His research was done for two regions: one population for the Ob and another population in Russian Zavorot. Valery is more specific in the exact pattern of the mirrors on P9 and P10, as he classifies mirrors as "open" (mirror reaches the edge of the feather) and "closed" (black of the medial band runs down along the feather edge, enclosing the mirror. He only found a few birds with broken sub-terminal black bands on P10 at the Russian Zavorot, by far most had a complete sub-terminal band.

And the distribution for P9 is illustrated below. Obviously, most birds have no mirror on P9.

For heuglini, the common pattern would be P9 without a mirror and P10 with open mirrors. This is a common pattern found throughout the Dutch population as well (see above). But also closed mirrors can be found at Moerdijk. Unfortunately Valery doesn't enlarge upon the exact definition of "closed"; should it be intense black running along the feather edge, or may it turn greyish over part of its range (commonly seen)? And when does grey becomes of-white or white so the mirror will be classified "open"? We can not really quantify the portion of Lesser Black-backed Gull at Moerdijk, showing this pattern due to extensive wear. End of addition Mars Muusse]

Iris Colour
In common with the other Siberian dark-mantled gulls and armenicus, antelius normally has some dark pigment in the iris. Only 5% of antelius have a completely yellow iris. In some 29% of individuals, the dark speckles in the iris cover only 2-5% of the total area, so that, from a distance, the iris appears completely pale. In the remaining 66%, the iris has a whitish, pale yellow or yellow background over which patches of grey, black or, occasionally, brown pigment are dispersed. The average percentage of the iris marked with dark pigment, estimated visually, is 23.4% (s.e, = 3.9, n = 39).

[additional data for graellsii: 78% (n=919) of Lesser Black-backed Gulls at Moerdijk colony had no or extremely limited iris speckling (<1% speckling). In this research, so-called 'clouded irides' (grey wash, honey coloured wash) were not scored as 'speckled'. The difference between sexes was significant (Mann-Whitney U = 92841, Z = -3.391, P = 0.001, male n = 431, female n = 488), with males having more speckling than females. We found 36 males (including eight sub-adults) with eyes falling into category III or higher but only 8 females. When sub-adults are excluded, the difference between sexes remains significant (Mann-Whitney U = 90245, Z = -2.948, P = 0.003, male n = 414, female n = 486).]

Orbital-ring colour
The orbital ring of about 80% of antelius is dark (coral-) red. The anterior part of the ring may be paler, and in 15% of individuals the orbital ring is a mixture of orange and red. In the remaining 5% it is orange, or even orange-yellow.

Lesser Black-backed Gull 63 graellsii male, May 09 2006, Moerdijk, The Netherlands (Mars Muusse). Iris speckling in right eye: >20%.	Lesser Black-backed Gull AV graellsii female, May 21 2005, Moerdijk, The Netherlands (Theo Muusse). Right iris speckling: >20%.
Lesser Black-backed Gull BK graellsii male, May 02 2006, Moerdijk, The Netherlands (Theo Muusse). Iris speckling: 10-20%.	Lesser Black-backed Gull CV graellsii male, May 06 2005, Moerdijk, The Netherlands (Mars Muusse). Iris speckling: 10-20%.

Leg colour
The legs of antelius are not uniformly coloured. The tarsus is usually paler and greyer than the rest of the leg, especially along the scales at the front of the leg. In normal field views, about 92% of individuals appear to have yellow legs (pale yellow, lemon-yellow or ochre) and 8% to have grey-yellow to grey legs, although the webs of the feet are always yellow. It appears that those with greyer legs tend to nest in colonies on marine islands.

Bill colour
Adult antelius has a yellow bill with a red-orange subterminal spot on the lower mandible. Of 37 adults collected near the nest, eight (22%) had a small black smudge or black band, 3-7 mm wide, on the bill.
In armenicus, the presence of black marks on the bill is a feature of young adults, and is not retained on older birds. I investigated whether this was also the case for antelius. Of the adult
antelius collected, 38% had longitudinal streaks of black or dark grey on some of the greater primary coverts, indicating, as with argentatus, that they were 3-4 years old. A statistical analysis showed that there was a significant correlation between the presence of black marks on the bill and black marks on the primary coverts, and therefore between the former and age (χ2 = 6.03; d.f. = 1; p < 0.01). In only 8% of individuals which showed definitive adult plumage were black areas found on the bill, these being very small marks 1-5 mm in extent.
In 5% of four-year old individuals, there were no black marks on the bill, but red pigment on the upper mandible at the level of the gonys, as is frequently observed on armenicus (Buzun 1993). I believe that red pigment on the upper mandible is a feature of young adults, because, on armenicus, the red colour is present on areas of the bill that were previously black.

[additional data for graellsii: 63% of all breeding birds at Moerdijk, the Netherlands had black on both mandibles. Black on the bill was found more frequently in females (table below). The difference between the sexes in the frequency of black was significant for both upper mandible (Pearson χ2 = 12.802, P = 0.000, male n = 435, female n = 492) and lower mandible (Pearson χ2 = 17.758, P = 0.000, male n = 433, female n = 491).
When sub-adult Lesser Black-backed Gulls (immature markings on the primary coverts) are excluded, 62% showed black on both mandibles. The difference between sexes in red and black markings remains significant when sub-adults are excluded from the sample (red on upper mandible, sub-adults excluded: Pearson χ2 = 70638, Z = -7.276, P = 0.000, male n = 391, female n = 475; black on both mandibles, sub-adults excluded: Pearson χ2 = 79572, Z = -4.176, P = 0.000, male n = 390, female n = 474). ]

[Note Mars Muusse: it is true that immature birds show more black on the bill than adults do. However and contra Buzun's statement, in taxon armenicus many adults keep black on the bill throughout the summer months. Filchagov, A.V. (1993) mentions: of 51 gulls examined closely, 33 had an unbroken black band on the upper mandible and a black spot in front of the red spot on the lower mandible, with some variation in the width of the band and the size of the spot. On another 16, the band was more or less reduced to a tiny spot on the upper mandible, again with much individual variation. Two had no black at all on the bill. Band pigment was of variable intensity, and was sometimes more grey than black.
Liebers & Helbig (1999) found 95% of armenicus on Tuz Gölu and Van Gölu to show prominent black bill marking, another 4% had faint markings and only 0,7% had black markings compleletly lacking.]

CONTINUE PART 3 >>>