OTTO FRENGEN PETER W. POST Figure 1. Breeding pair of L. f. fuscus in typical definitive alternate Figure 2. Typical example of intermedius from the west coast plumage. Note the even blackish color of the back and wings of Sweden. The back and wings are lighter than in fuscus, and the relative lack of contrast with the black primaries, the small and the contrast with the black primaries is therefore greater. white primary spots, the long wings with the tip of the tail opposite Hållo, Bohuslän Province, Sweden. 16 July 1992. or falling short of the fourth primary tip, and the relatively long yellow legs. Horsvaer, northern Norway. June 1986. ROGER TIDMAN ROBERT H. LEWIS Figure 3. A typical graellsii. The shade of gray, and the contrast with Figure 4. A Dutch intergrade (intermedius × graellsii) showing the the black primaries, precludes this bird from ever being mistaken for mantle and wing–color characteristic of the majority of Lesser any other subspecies of L. fuscus, despite the small size of the white Black-backed Gulls breeding in the Netherlands. Maasvlakte, primary tips caused by wear. Northumberland, England. June 1982. Rotterdam. 16 July 1994. 282 BIRDING. AUGUST 1995 The Lesser Black-backed Gull in the Americas Occurrence and Subspecific Identity Part I: Taxonomy, Distribution, and Migration cently been discovered breeding in 1950 to 1994. Sight and speci­ PETER W. POST * † Greenland (Boertmann 1994), and men records continued to accu­ and ROBERT H. LEWIS † one, mated to a Herring Gull, was mulate at a slow rate from 1950 found breeding in southern until the mid-1970s, when the Gull watching is one of the Alaska (van Vliet et al. 1993). number of reports per year be­ most challenging and rewarding gan to rise noticeably, if not ex­ aspects of birding. This is no Discovery ponentially. By the 1980s, L. fus­ doubt due in part to the large and Expansion cus had been recorded from all population of gulls, the ease with in the New World of eastern and central Canada which they can be observed, the 1850 to 1949. The first North and from all the Great Lakes subtle identification challenges American records of Lesser states and along the entire Atlan­ they present, and the exciting Black-backed Gull consist of tic and Gulf coasts of the US. possibility of finding a wanderer specimens collected in Greenland As of the first half of 1994, from another coast or continent. in 1850 (Boertmann 1994; Table Lesser Black-backed Gulls have For much of the past forty 1) and on 15 April 1920 (Salo­ been reported in all 31 states and years, one of the most eagerly monsen 1967; Table 1). The first the District of Columbia in the sought prizes in the northeastern bird reported for North America eastern half of the United States, US and eastern Canada has outside Greenland was an indi­ except for West Virginia (De­ been the Lesser Black-backed vidual seen on 9 September 1934 Sante and Pyle 1986; White 1990; Gull (Larus fuscus) of northern at Beach Haven, Ocean County, Hall 1993; Stedman 1994). In the and western Europe. But in the New Jersey (Edwards 1935). Great Plains states it has oc­ last two decades, this species has This record was followed by curred once in North Dakota undergone a continent-wide ex­ eight reports of birds from the (Martin 1991) and three times in pansion and is no longer re­ coastal New York City and New Nebraska (Silcock and Roche stricted to the Northeast, nor Jersey area in the late 1930s and 1994), and at least one bird has even in the New World to the 1940s (Kuerzi and Kuerzi 1935; occurred annually since 1984 in US and Canada. The total num­ Elliott 1940; Cruickshank 1942; Oklahoma (Newall 1984; J.A. ber of Lesser Black-backed Gulls Alexander 1946), a 1938 report Grzybowski, pers. comm.). Far­ seen on the National Audubon from Key West, Florida (Sprunt ther west it has occurred at least Society Christmas Bird Counts 1938), a 1948 specimen from thirteen times in Colorado has been increasing every year Maryland (Buckalew 1950; Ta­ (Webb and Conry 1978; R. and is still increasing, ln fact, the ble 1), a 1948 record from Indi­ Knight, pers. comm.), once in Lesser Black-backed Gull has re­ ana (Brock 1979), which is the Utah (Kingery 1991), and six earliest inland record for North times in California (Binford *141 West 73rd Street, New York, New America, and a 1949 specimen 1978; Small 1994). There are also York 10023-2917 † 176 Hunter Avenue, North Tarrytown, from upstate New York (Beard­ three acceptable records from New York 10591-1315 slee and Mitchell 1965; Table 1). southeastern Alaska (Gibson and TAXONOMY. DISTRIBUTION, AND MIGRATION 283 Lesser Black-backed Gull Kessel 1992; T.G. Tobish, pers. list (1983), Lesser Black-backed ton 1988a; Raffaele 1989), St. comm.), including a specimen Gulls winter regularly in small Croix (Norton 1986), Antigua (Gibson and Kessel 1992; numbers in North America from (Norton 1988b), Aruba (Voous Table 1) and a bird found mated the Great Lakes region, Labra­ 1977, 1983), St. Martin (Voous to a Herring Gull near Juneau in dor, eastern Québec, and New­ and Koelers 1967; Voous 1983), 1993 (van Vliet et al. 1993). foundland, south to Florida and Trinidad (ffrench 1991), Tobago In Canada, L. fuscus has been along the Gulf coast west to (ffrench 1991), Mexico (Howell recorded in all ten provinces and Texas. The first report of Lesser and Webb 1995), Venezuela (Alt­ in the Northwest Territories (De- Black-backed Gulls on a Christ­ man and Swift 1989), Guyana Sante and Pyle 1986; White mas Bird Count (one each from (D. Finch and A. Maley, pers. 1990). Although regular well in­ New York and Kings counties, comm.), French Guiana land in southern Ontario, it is New York) was during the 1962– (Devillers 1979), and on the Pa­ still casual in the Prairie Prov­ 1963 season (Cruickshank 1963). cific coasts of Panama (Smith inces: it has occurred about four Thirty years later, the 1992–1993 1982) and Costa Rica (S. times in southern Manitoba in counts (including count week) re­ Perkins, pers. comm.). ln addi­ the Winnipeg area (P. Taylor, corded 160 individual Lesser tion to the birds that come from pers. comm.) and four or five Black-backed Gulls on 86 counts the northern Palearctic, it is also times in northern Manitoba at in three Canadian provinces, likely that some birds directly Churchill (P. Benham, J. Schulen­ twenty-one states, and the Dis­ cross the Atlantic to the south­ berg, and P. Taylor, pers. trict of Columbia (Le Baron eastern US and the Caribbean comm.), five or six times in Sas­ 1993). One hundred forty-three from southern Europe or the Af­ katchewan (R. Kreba, pers. of these birds were found from rican coast. comm.), and about four to six Newfoundland on the Atlantic An “immature” gull collected times, with only one confirmed, seaboard to Texas on the Gulf in Argentina on 26 March 1931 in Alberta (P. Sherrington, pers. coast, eleven in the Midwest and identified by Robert Cush­ comm.). It has occurred twice in (Ohio, Michigan, Indiana, Illi­ man Murphy as a Lesser Black- British Columbia (Campbell nois, Iowa), one in Kentucky, backed Gull (Steullet and Deau- 1990; Siddle 1994). The first Ca­ one in Tennessee, and three in tier 1939) may be an example of nadian record was at Churchill Bermuda. The largest number of Olrog’s Gull, L. (belcheri) atlan­ in 1968 (Godfrey 1986). individuals recorded were from ticus (Narosky, pers. comm.). Ron D. Weir and Ron Ridout New York to North Carolina The specimen is extant (N.A. have provided a table detailing (100) and in Florida (9), latitudes Bó, pers. comm.) and needs to be the explosive increase of reports equivalent to the main wintering reexamined. in Ontario from 1977 to 1993 areas in the Old World. Maximum numbers of L. fus­ (Table 2). Tove (1989) provides An early analysis of North cus seen in a single day include: a similarly dramatic chart for American Lesser Black-backed 11 from the Chesapeake Bay North Carolina and South Caro­ Gull records by Webb and Conry Bridge and Tunnel, Virginia, 26 lina, and, indeed, comparable ta­ (1978) indicated that “some indi­ October 1985 (R.D. Barber, bles could probably be prepared viduals migrate through the US, pers. comm.); 31 at Cape Point for many states and provinces perhaps to winter farther south on the North Carolina Outer bordering the Atlantic Ocean, along the coasts of Mexico, Cen­ Banks, 28 January 1995 (E.S. the Great Lakes, and the Gulf of tral and South America, and in Brinkley, pers. comm.); 35 at the Mexico. The Lesser Black- the Caribbean Islands”. Indeed, Pompano landfill, Pompano, backed Gull is recorded regularly to the south of the US, there are Florida, 10 April 1993 [although in Greenland, where it is also in­ reports of L. fuscus (although the published report (Langridge creasing. The species occurs regu­ many of these lack any details) 1993) states these last birds were larly in Bermuda (Amos 1991). from Abaco in the Bahamas all “immatures” ,according to According to the AOU Check­ (Norton 1994), Puerto Rico (Nor­ the observer about a dozen were 284 BIRDING. AUGUST 1995 part I adults, the rest first- and second- summer birds, were at Hart- Gull (L. argentatus) group is ex­ year birds (A. Wormington, pers. Miller Island, Maryland, 20–31 tremely complex. For the pur­ comm.)]; and 40 at Penn Manor July 1992 (Armistead 1992). poses of this article we follow Lakes and landfill, Bucks Grant (1986), who treats L.