Gulls of the World a Photographic Guide
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© Copyright, Princeton University Press. No part of this book may be distributed, posted, or reproduced in any form by digital or mechanical means without prior written permission of the publisher. 172 Larus 27. ICELAND GULL Larus glaucoides L 52–60cm; W 125–145cm Identification Four-year gull. An elegant, medium- birds, plumage bleaches to whitish from late winter, sized arctic gull. Plumage essentially identical to losing any strong pattern. In first-summer very pale. Glaucous Gull, with wing-tip in younger birds paler Second-winter (Aug–Apr) similar to first-year, but than rest of plumage. In size and shape intermediate more unevenly patterned. Head and underbody either between large and medium-sized gulls. Small rounded paler with restricted dark, more diffuse markings or head, large eyes and short, weak bill create ‘mild’ more extensively dark-marked. Upperparts often with expression and Common Gull-like impression in all scattered grey feathers in mantle and scapulars; most but large males. In settled birds, breast is broad and advanced birds have grey saddle. Coverts pattern more pigeon-like, body slender with well-marked tertial- irregular and waved, especially in greater coverts, which step and wings very long, extending well beyond tail may be most densely patterned part of the plumage. (projection equal to bill length or longer). When Rump white with faint dark barring. Flight feathers relaxed, wings often held lowered. Legs short with little pale, sometimes with diffuse brown-tinged outer webs visible tibia. and markings near tips to a varying numbers of prima- Large males have more sloping forehead, longer ries, including innermost. Eye yellow. Bill pale with bill and proportionally shorter wings. Some approach black subterminal bar or tip. size of Herring Gull but lack its fierce, masculine aura. Second-summer (Apr–Aug) as bleached second- Small females have rounded head, smallish bill and the winter; head and underbody paler through wear. Grey longest wings, appearing short-legged and long-bodied mantle/scapulars contrast well to pale bleached upper- with jizz similar to Common Gull ssp. heinei. wing. In flight, short rounded head contrasts to deep Third-winter (Sep–Apr) similar to adult, but parts of breast on short body. Wing long and narrow with long, coverts pale brown and finely barred. Flight feathers slender hand. The flight is quicker and more agile than and tail off-white, tail and outer webs of especially outer in larger gulls. Handles strong winds well and often primaries often diffusely dark-marked. Bill dull yellow performs ‘shearing’ glides on angled wings. Associates with dark subterminal markings and small amount of with smaller gulls to pick food from surface. Feeds also red on gonys. by scavenging, but tends to stay away from gatherings Fourth-year similar to adult, but with scattered brown- of larger gulls. Often in small groups. tinged coverts (especially primary coverts), and some- Juvenile/first-winter (Jul–Apr) Head and underbody times traces of weak dark barring in undertail coverts greyish-brown to pale buff; hindneck often paler from and dark subterminal spots in yellow bill. late autumn. Upperparts pale greyish-brown to buffish Adult underbody, underwing coverts and tail white. with diffuse darker marblings or arrowhead mark- Upperparts pale grey (Kodak grey scale (2)3–4), wings ings, generally strongest on scapulars and broadest in with broad white trailing edge and broader white tip. darkest birds. Coverts finely brown-marked. Tertials Bill yellow with red gonys spot. Eyes pale yellow. Orbital with often indistinct brown markings and broad pale ring red. Legs pink. In summer (Mar–Aug/Sep) head edges. Rump and tail coverts white with brown barring, white; in winter (Sep–Mar) head brown-spotted or most distinct in undertail coverts. Primary coverts streaked, sometimes indistinct. Bill generally duller often slightly darker with narrow dark subterminal with olive or greenish tinge, sometimes with narrow markings. Flight feathers pale greyish-brown to off- dark markings. white, often with narrow dark V-markings near tips and Voice Shriller and higher-pitched than in American indistinct vermiculations in inner primaries. Tail with Herring Gull; long-call with slower elements (2 per variable amount of pale brown barring, sometimes second versus 4 in American Herring). as strong as in uppertail coverts to form diffuse tail- Moult notes Adult moult to winter complete May– bar. Bill dark with fleshy, grey, greenish or bluish base Nov. Retarded birds (all ages more than one year) may diffusely divided from broad black tip. Eyes dark. Legs suspend primary moult until Nov with worn, brown- fleshy. tinged outer primaries in contrast to new grey inners. Juvenile plumage often retained throughout winter, Moult to summer partial from late Jan, including head but some renew part or all of mantle and scapulars in and body. Juvenile plumage either retained to Mar or late autumn. New feathers more greyish-tinged with with parts of mantle and scapulars (rarely all) renewed narrower and better defined dark markings than in in late autumn. Moult complete to second-winter Apr– juvenile, sometimes reduced to shaft streaks. In paler Oct. Flight feather moult earlier and slower than in For general queries, contact [email protected] 004 Gulls species.indd 172 18/10/2017 14:43 © Copyright, Princeton University Press. No part of this book may be distributed, posted, or reproduced in any form by digital or mechanical means without prior written permission of the publisher. Gulls 173 ? L. g. glaucoides L. g. 'kumlieni' adults. Subsequent moults similar to adult, but gener- darker birds have fuller and more complex dark ally earlier, starting with p1 in Mar. pattern, as ‘ghost-version’ of adult pattern, in settled Geographical variation Iceland Gull ssp. glaucoides birds appearing as darker wing-tip than body. There described above. may be indication of white mirrors in outer webs of Kumlien’s Gull (Larus glaucoides ‘kumlieni’). Here p9–10, which is never paler than rest of plumage as in treated as a hybrid swarm between Iceland and glaucoides. From below, dark-patterned feathers often Thayer’s Gulls on basis of enormous individual varia- show up as dark trailing edge in outerwing. Supporting tion, presenting all types of intergrades between the characters are more extensive dark markings in upper- two species. Most published material stems from parts, slightly darker secondaries and tendency to show wintering birds in Newfoundland. Influx to N Atlantic complete, dark-waved tail-bar. Bill often all-dark, fewer in winter 2011/12 involved birds with paler and more with pale base as in glaucoides. Generally moults more restricted wing-tip markings on average, whereas most of upperparts plumage to first-winter thanglaucoides from NE Great Lakes have stronger pattern than the does. majority from Newfoundland. Second- to fourth-years gradually develop adult-like Size and jizz similar to glaucoides, but on average primary pattern, but fainter in two/three-year birds, larger and heavier with slightly shorter wing projec- normally with darker markings along outer webs and tion and sometimes more sloping forehead. Very small, tips of p6–10. Some have darker outer webs to basal extremely long-winged birds as in glaucoides are at part of primaries, but outwashed paler distal parts with most very rare. Adult similar to glaucoides, but upper- faint dark markings near tips. In such birds, wing-tip parts often slightly darker (Kodak grey scale 3–4(5)). appears ‘dirty’ with uneven pattern. Most have exten- Primaries have well defined darker pattern, ranging sive dark-patterned wing coverts (especially greater) from indistinct markings in outer web and tip to p10 and extensive dark shading in tail, creating ghostly to greyish-black markings in p6–10, similar to pattern grey tail in contrast to white rump. Bill often darkish of Thayer’s Gull, but with paler grey tinge, more exten- even in second-years. Eyes often dark, but may become sive white and at most very indistinct markings in p5. paler from second-winter. P8 often most extensively marked and slightly darker Hybridisation If Kumlien’s Gull is regarded as a hybrid than p9–10. Easily identifiable birds have medium- swarm between Iceland and Thayer’s Gulls, no other grey streaking in 3–4 outer primaries (Kodak grey cases of hybridisation known; situation complicated by scale 7–10), in settled birds creating grey wing-tip with lack of knowledge from remote breeding sites. white primary tips. Most have faint dark markings near Status, habitat and distribution Nominate glaucoides primary tips. Some are as unmarked as glaucoides, and breeds on steep cliffs along rocky coasts, mainly in are not identifiable on plumage alone; dark eyes are western Greenland. May have bred Jan Mayen in the a supporting character, as adult glaucoides has pale 19th century. Most of southern and western popula- yellow eyes. In ‘kumlieni’ eyes are darker yellow, dark- tion sedentary, but populations from north and east peppered or darkish. Winter head pattern generally Greenland spread in winter northwards to Thule. Some more extensive than in glaucoides. migrate south-east to reach Iceland, where concentra- First-year generally darker than glaucoides with tions of hundreds winter. Smaller numbers continue contrasting darker pattern in outer primaries. further south-east to Faroe Islands, Ireland, Britain Weakest-marked birds show slightly darker outer than and NW Europe. More reach Europe when winter in inner webs and dark tips to outer primaries, whereas Greenland is severe. Vagrant Finland, continental W, For general queries, contact [email protected] 004 Gulls species.indd 173 18/10/2017 14:43 © Copyright, Princeton University Press. No part of this book may be distributed, posted, or reproduced in any form by digital or mechanical means without prior written permission of the publisher.