glaucoides & kumlieni

(last update: October 12, 2011)

Iceland & Kumlien's Gull sub-adult January - April

Below you'll find a copy of the 1992 article "Recognizable Forms - Subspecies of the Iceland Gull" by Ron Pittaway published in: ONTARIO BIRDS APRIL 1992. The PDF version can be downloaded here: PDF PITTAWAY.

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

Recognizable Forms - Subspecies of the Iceland Gull

by Ron Pittaway published in: ONTARIO BIRDS APRIL 1992

Introduction

The taxonomy of the Iceland Gull (Larus glaucoides) is complex and much debated by ornithologists and birders. In this account, I hope to clear up some of the confusion about the status and identification of the three Iceland Gull subspecies in Ontario - the Kumlien's Gull (L.g. kumlieni, Thayer's Gull (L.g. thayerii), and the nominate "Greenland" race (L.g. glaucoides). Here I follow Godfrey (19861 and James (19911 who consider the Thayer's Gull to be a subspecies [race] of the Iceland Gull.
I refer the reader to Plate 36 and the excellent discussion on the Iceland Gull in the revised edition of The Birds of Canada (Godfrey 1986). (Dr. Earl Godfrey is an internationally recognized taxonomist and leading authority on the Iceland Gull.)

Kumlien's Gull:

Kumlien's Gull, pronounced "KOOM-leans" (Terres 1982). breeds in the eastern Canadian Arctic and winters mainly in the Atlantic provinces and Gulf of St. Lawrence, with small numbers on the Great Lakes (Godfrey 1986). Contrary to what many Ontario birders believe, Kumlien's is the most common race of the Iceland Gull in the province. The impression that it is rarer than the nominate "Greenland" race (L.g. glaucoides) has persisted for a long time. This misconception likely resulted from the fact that the variable grey markings on the wingtips of many adult Kumlien's are difficult to see and can be easily overlooked on distant birds. As well, immature birds are more frequent in southern Ontario than adults, and there has been an assumption that these "white-winged" immatures are of the nominate race.

Adult Kurnlien's Gulls have darker grey mantles than adults of the nominate race, and adult Glaucous Gulls (L. hyperboreus), In fact, many Ontario adult Kumlien's have mantles almost as dark as Herring Gulls (L. argentatus) (Richard Poulin, pers. comrn.). Typical adults, which have light to moderate pigmentation in the wingtips, can be reliably identified to race. However, beware of the fact that the Nelson's Gull (Herring X Glaucous hybrid) is rare, but regular, in Ontario. Some are similar to Kumlieri's, but are usually distinguishable by their larger size and heavier bills.

First winter Kumlien's average darker than nominate birds. Most are probably indistinguishable in the field (Godfrey 1986). However, those somewhat darker than normal individuals having considerable dark smudging in the wingtips and darker tails are probably safely called Kumlieri's, but see the reference to intergrades under Thayer's Gull. For further discussion and excellent photographs of Kumlien's Gull, the reader is referred to the recent article in Birding by Zimmer (1991).

Thayer's Gull

Thayer's Gull was once considered a subspecies of the Herring Gull, and more recently a separate species by the American Ornithologists' Union (1973). based primarily on the studies of Smith (1966). Gaston and Decker (1985), Godfrey (1986), and Snell (1989) have reported interbreeding between Kumlien's and Thayer's Gulls, contrary to Smith (1966). It is now apparent that the Thayer's Gull represents the dark extreme of the Iceland Gull complex (Godfrey 1986).

Thayer's Gulls breed in the western and high Arctic, and winter mainly on the West coast. Small
numbers occur in migration and winter in southern Ontario. Typical adult and first year Thayer's Gulls can be distinguished from Kumlien's Gulls "with considerable confidence in the field" (Godfrey 1986). Intermediates between Thayer's and Kurnlien's may represent either extremes in variation or intergrades ([Gaston and Decker 1985, Godfrey 1986, Zimmer 1991).

Beware of two identification pitfalls. First, an occasional aberrant Herring Gull can have a Thayer's-like wing pattern. The Herring's bright yellow eyes and yellowish (instead of reddish) fleshy orbital rings should serve to distinguish it. Second, some Herring X Glaucous Gull hybrids
(Nelson's Gull) closely resemble Thayer's Gulls. Their larger size, paler mantles, and heavier bills should distinguish the hybrids. First year hybrids usually have bicoloured, Glaucous-like bills. Detailed discussion of Thayer's Gull identification may be found in Godfrey (1986), Gosselin and David (1975), Lehman (1980), and Zimmer (1990).

"Greenland" Iceland Gull

Godfrey (1986) states that the nominate race (L.g. glaucoides) is "a non-breeding visitor, mostly in winter, to southeastern Canada from the breeding grounds in southern Greenland". It is by far the rarest of the three subspecies in Ontario. Earl Godfrey (pers. comm.) has confirmed that there is an adult specimen of the nominate race from Ontario in the National Museum in Ottawa. This specimen was collected on 28 November 1974 at Ottawa by Richard Poulin. Another small and very pale first winter bird, collected 5 December 1974 at Ottawa by the author and Richard Poulin, is "almost certainly" of the nominate race (Earl Godfrey, pers. cornm.).

The field identification of nominate birds in Ontario should be attempted with extreme caution. Nevertheless, a classic individual should be recognizable. For a winter adult (compared with Kumlien's), the combination of immaculate primary tips, smaller size, slighter bill, very pale Glaucous-like mantle, clear yellow eyes, and pale spotting confined to the head and nape add up with reasonable certainty to L.g. glaucoides. Bruce DiLabio [pers. cornm.) observed such a classic nominate adult in direct comparison with adult Kumlien's and Glaucous Gulls at the Cornwall Dam on 19 January 1991. First year birds cannot be identified subspecifically in the field (Godfrey 1986). However, small and very pale first winter birds, having pale at the base of the bill, are suggestive of the nominate race. See Figures 2 and 7 in Zimmer (1991). For additional discussion of identification, see Godfrey (1986) and Grant (1986).

Summary

Kumlien's Gull is the most frequently occurring subspecies of the Iceland Gull in Ontario. The majority of adults can be reliably identified to race in the field. Most first winter birds are probably indistinguishable from nominate birds. Thayer's Gull is of regular occurrence, but somewhat less frequent than Kumlien's Gull. Typical adult and first winter Thayer's can be distinguished from Kumlien's with considerable confidence in the field. The occurrence of nominate Iceland Gulls in the province is supported by a specimen in the National Museum. However, this subspecies is extremely rare here, and should be identified with great caution.

Classic adult nominate individuals are recognizable in the field with a high degree of certainty. Most first winter birds are not separable in the field from Kumliens. As a final note on gull identification, don't be afraid to say "I just don't know what it is!"

Acknowledgements

1 wish to thank the following who provided me with much valuable advice and information: Bill Crins, Bruce DiLabio, Earl Godfrey, Chris Lemieux, Bruce Mactavish, Richard Poulin, and Ron Tozer.

Literature cited

American Ornithologists' Union 1973. Thirty-second supplement to the American Ornithologists' Union Check-list of North American Birds. Auk 90: 411-419.
Gaston, A.J. and R. Decker 1985. Interbreeding of Thayer's Gull, Larus thayeri, and Kurnlien's
Gull, Larus glaucoides kumlieni, on Southampton Island, Northwest Territories. Canadian Field-Naturalist 99: 257-259.
Godfrey, W.E. 1986. The Birds of Canada. Revised Edition. National Museum of Canada, Ottawa.
Grant, P.J. 1986. Gulls: A Guide to Identification. Second Edition. Buteo Books, Vermillion, South Dakota.
James, R.D. 1991. Annotated Checklist of the Birds of Ontario. Second Edition. Royal Ontario Museum, Toronto.
Lehman, P, 1980. The identification of Thayer's Gull in the field. Birding 12: 198-210.
Smith, N.G. 1966. Evolution of some arctic gulls (Larus): an experimental study of isolating mechanisms. Ornithological Monographs No. 4. American Ornithologists' Union.
Snell, R.R. 1989. Status of Larus gulls at Home Bay, Baffin Island. Colonial Waterbirds 12: 12-23.
Terres, J.K. 1982. The Audubon Society Encyclopedia of North American Birds. Alfred A. Knopf, New York.
Zimmer, K.J. 1990. The Thayer's Gull complex. Pp. 114-130. in A Field Guide to Advanced
Birding (K. Kaufman). Houghton Mifflin Co., Boston.
Zimmer, K.J. 1991. Plumage variation in "Kumlien's" Iceland Gull. Birding 23: 254-269.

pale end birds in Europe, classic glaucoides

darker birds, still probably glaucoides

pale birds, but primary patterns with sub-terminal bands advocate kumlieni

dark outer primaries classic for kumlieni