Identification of Kelp Gull Frederic Jiguet, Alvaro Jaramillo and Ian Sinclair

Identification of Kelp Gull Frederic Jiguet, Alvaro Jaramillo and Ian Sinclair The Kelp Gull Lams dominicanus has recently suggest that they are resident, while birds in been recorded in the Western Palearctic for the Australia and New ZeaJand undergo only short first time (Pineau et al. 2001), while its regular distance movements away from the breeding occurrence elsewhere in the North Atlantic grounds in winter (at most 600km; Higgins & region is now clearly proven, eg in Senegal, the bavies 1996). Gambia, Mexico and Louisiana & Texas, USA. In Africa, the race vetula is a regular winter There have also been sightings in Maryland and visitor to well north of the tropics on both the Indiana in the United States - at about the same Atlantic and Indian Ocean coasts. Areas north latitude as Lisbon, Portugal - although the of Namibia (where the birds are comm011 North American records are currently still breeders on the mainland and offshore islands.), being assessed by the ABA and AOU. Angola, Gabon and the Gulf of Guinea are not fn 1980 and 1983, isolated breeding was regularly watched and the species could be recorded at Saloum delta, northern Senegal easily overlooked there. IS has seen Kelp Gull in (Dupuy 1984, Erard et al. 1984). Also, immah1re Angola both times he has been there, and as far gulls considered to be of this species were north as Lobito. On the Indian Ocean coast, the recorded from Ngor Island, off Senegal, on 14th species is regular at Maputo, Mozambique, October 1995 (three) and 6th October 1996 fairly regular at Bazaruto Island, and has been (Marr et al. 1998). Hybridisation with American recorded in Beira. The Kelp Gull recorded at Herring Gull L. (m·gentatus) smifhsonimnis occurs Malindi, Kenya, in 1984 was almost certafaly L in Loujsjana (Dittman & Cardiff 1998), while d. vetula (D.A. Turner pers. comm.). At least six Pineau et al. (2001) reported attempted hybridis· Kelp Gulls thought to be of the Antarctic form ation with Yellow-legged Gull L. micho.hellis. dominica1111s have been seen in South Africa (P. Ke.Ip GulJ breeds along the coasts of all Ryan in lit.) southern continents. There have been few Vagrant Kelp Gulls in West Africa and the detailed studies on geographical variation Western Palearctic could have their origins in within the species, but Higgins & Davies (1996) southern Africa, but vagrants in North America suggest that latitudinal and longitudinal ana· more likely originate in South America. The lyses of measurements might reveal dines. Middle East is another potential area of Brooke & Cooper (1979) recogrused the race vagrancy for Kelp Gull. vetula from South Africa (also known as Cape This article on the identification of Kelp Gull Gull) on the basis of larger size and dark iris of is based on extensive field studies throughout breeding adults, wh.ile Chu (1998) found vetula the species' range - on Crozet, Kerguelen, to be quite distinct from domi11icm111s. However, Heard, Marion and Prince Edward Islands, birds from South America, particularly in Chile, New Zealand, Antarctica, PalkJand Islands and commonly ShQw dark eyes, and birds from South Georgia, South America, southern Africa Antarctica are also particularly large. and Madagascar - as well as on the examination Only the Antarctic populations .are truly of specimens at the MNH..-i\J in Paris and Tring migratory. These birds leave their breeding museum. Descriptions of differences between grounds in winter and disperse to the north, populations studied are given and offered as a although they can winter only as far north as starting point for determining patterns of geo· the edge of the pack ice (Parmelee 1992). Ringed graphic variation in greater detail. Antarctic birds have been recovered in South The taxonomic treatment adopted in this America, but only from the extreme south (all paper alms to be taxon specific, except that, for south of Rio Gallegos in Patagonia and Tierra more clarity in the following descriptions, both del Fuego). Studies of subantarctic populations L. d. dominicauus and L. d .. vet11la (Cape GuJI) (on the Crozet archipelago and South Georgia) have been maintained under the name Kelp 112 Gull. English and corresponding scientific In Lesser Black-backed and Baltic Gulls, P9 names are used as follows: Baltic Gull L. fuscus and PlO are nearly of equal length and appear fuscus, Lesser Black-backed Gull L. ftlSCUS graell to fall together, but Pl0 is generally slightly sii / intermedius, Caspian Gull L. cachil1nal1s, longer than P9. Furthermore, in these taxa, P5 Yellow-legged Gull L. michahellis, American often extends beyond the tertials on the folded Herring Gull L. argel1tatus smithsoniallus and wing, so that five or up to six primary tips are Great Black-backed Gull L. marinus. visible beyond the tertials in the folded wing, Note that primaries are named from inner and the wings generally extend well beyond the most (Pl) to outermost (Pl0); Pll is minuscule tail-tip at rest, with the tail-tip ending between and largely hidden by the primary coverts. P6 and P7, but often close to P6. Overall, Lesser Black-backed Gull and particularly the long Structure and general appearance When trying to establish differences in size and distance migrating Baltic Gull appear slimmer structure between gull species, one should and longer due, in part, to their longer wing always keep in mind that there is considerable projection. Kelp Gulls from all populations can variation due to age, individual variation and easily be distinguished from Baltic Gull in all sexual dimorphism (Gruber 1999). age groups by their much shorter wings. Kelp Gull body size is highly variable, with • Another obvious difference is the size of the the largest birds occurring in Antarctica and legs: Kelp Gull has thick and fleshy tarsi South Africa, and the smallest in the southern whereas Baltic Gull has longer, thinner 'match Indian Ocean. Small Kelp Gulls are close in size stick-like' tarsi. to Lesser Black-backed Gull, but the largest The leg structure and size differences birds can be bigger than Yellow-legged Gulls, between Kelp Gull and Baltic Gull are obvious and can easily recall Great Black-backed Gull. where the wintering ranges of the taxa overlap. The sexes are similar in plumage, but the male Kelp is larger and more thick-set, with a more is larger and bulkier, with a more powerful bill. angled and 'fierce' appearance to the head. The Kelp Gull is a black-backed gull with a Note, however, that Kelp Gulls in summer with thick-set, deep-chested appearance, large head worn and faded plumage can look slim and with sloping forehead, small eye, and broad, long-legged. rounded wings extending a little beyond the Plate 1. Adult Kelp Gull Larus dominicanus, Maryland, USA, tail-tip at rest; the tail-tip aligns close to P7. The 4th March 1999 (Jim 8angma) . bill is thick and heavy, with a prominent Kelp Gulls have already reached the eastern USA and the southernmost Western Palearctic - so Europe next? gonydeal angle. Geographical variation exists in bill size and shape (and can be obvious), but the bill is always large at the gonys. The bill is deep at the base so, while there is a gonydeal angle, the bill is not necessarily much deeper at the angle than at the base, and thus the species sometimes lacks a 'blob-ended' bill. The combination of these features creates a distinc tive silhouette. Populations from the Antarctic Peninsula and nearby islands are large, but relatively short-billed compared to South American birds. Four primary tips (P6-P9) are generally visible beyond the tertia Is on the folded wing, with Pl0 concealed by the same-length or longer P9 . In some birds, especially in Antarc tica, P5 can be seen just emerging from the tertial crescent. Thus the wing is moderately short and rounded (Pl0 concealed by P9); it is also broad, such that the secondaries overshoot the upperwing greater coverts on the folded wing (with the white secondary tips visible). 113 Moult understanding of moult timing is that it elimi A few general comments on the moult that nates the hypothesis that there are two partial involve some speculation away from what is moults before the first complete moult, and this generally understood on gulls (ie Dwight 1925 matches the moult pattern shown by waders and Grant 1986) is included here. Pre-breeding and terns. In essence, it brings the gulls into line (Pre-alternate) moults appear to be lacking in with the other Charadriiforms. first-year gulls (Howell et al. 1999), so a juvenile The beginning of the primary moult in the moults into a first-winter plumage (partial third post-breeding (pre-basic) moult is later moult) and then to a second-winter plumage than in the second post-breeding moult, and (complete moult) There is no first-summer there may be a pre-breeding moult involved, plumage that is obtained by a partial moult in but it may also be just a protracted complete the spring. Note, however, the odd moult moult. timing shown by Baltic Gull (see end of this Full adult plumage is acquired in the fourth section). Howell et al. (1999) suggest that moult year. As in other large white-headed gull in immature large gulls is a nearly continuous species, the winter plumage (except the first process, making the classification of moults and one) is acquired by a complete post-breeding plumages troublesome. • (pre-basic) moult, whille the adult summer In the Austral spring, October-November, a plumage results from a partial pre-breeding Kelp Gull that is less than one year old begins moult that involves generally only the head and to moult its primaries; this is certainly a com body feathers.

Load more