80                           NORTHERN GULLS IN ARUBA                  [Ardea64


                                 K.H. VOOUS

                  Biological Laboratory, Free University, Amsterdam
                    Zoological Museum, University of Amsterdam

  Through the kindness of several correspondents in Aruba, notably E.
Jansen and C. J. Hey, I have been able to collect new data on the occurrence
of four species of gull, three of wich have not previously been recorded in
the Antillean islands of Aruba, Cura<;ao and Bonaire (Voous 1965). The data
have been substantiated by sending of colour-slides or colour-prints. To all
correspondents in Aruba I tender my sincerest thanks.

   Larus marinus (1) - 24 Nov. 1971, first recorded by W. H. & Andrew D.
Heineman (New York) on the Aruba Hotel Beach, sitting on a boat amidst a
group of Laughing Gulls L. atricilla. The bird stayed until Feb. 1972 (Jansen).
It was apparently in nearly if not complete adult plumage,
   Larus marinus (2) - 1 Oct. 1972 - 28 Jan. 1973, Hadicourari, among other
gulls (Jansen). Thought by Jansen to be different from the bird of previous
year, but colour-slide gives same impression and the bird (now in adult
plumage) was sitting on exactly the same spot.
   Larusfuscus (1) - 25 Aug. 1973, Manchebo Beach. Adult bird among flock
of Laughing Gulls (Hey).
   Larus fuscus (2) - 29 Sept. 1973, at water purification plant (Hey). Legs
light, yellowish. Not seen next day or afterwards.
   Larus fuscus (3) - 13 March - 15 Aug. 1975, at water purification plant.
Adult bird, also seen 16 May and 11 June (Hey). Legs yellowish. Colour-
picture made 13 March by A. C. M. de Groot does not make it sure whether
the bird is L. marinus or L. fuscus, but it resembles L. fuscus by shape (long
wings), leg colour (pale yellow), and size (similar or slightly smaller thanL.
argentatus on the same picture).
   Larusfuscus (4) - 5 Dec. 1975, beach beyond Divi-Divi Hotel.One bird at
the rear of a flock of Royal and Common Terns and Laughing Gulls (Dr.
Joan Criswell and Sarah S. Baker, Washington, D.C.). According to the
description given, most likely a bird in adult winter plumage.
   Larus argentatus (1) - 7 Nov. 1972, Hadicourari, juvenile bird in the dark
first year plumage of the race smithsonianus, alongside adult L. marinu.s
   Larus argentatus (2) - 13 March 1975, at water purification plant. Adult
bird sitting among Laughing Gulls and one probable L. fuscus (3) (Hey).
Colour-picture by A. C. M. de Groot shows mantle colour only slightly
lighter than Laughing Gulls.
   Larus de/awarensis (1) - 20 Jan. 1972, Hadicourari, one bird in immature
plumage, photographed when sitting amongLaughing Gulls (Jansen).
1977]                       NORTHERN GULLS IN ARUBA                         81

   The occurrence of these gulls conforms with the present trend of increased
observations of northern gulls in the West Indies, where of all gulls the
Laughing Gull is the only regularly occurring and well known species, both
wintering and nesting. It is not known whether the increased number of
records reflects a trend of increasing numbers of North American gulls (as
sometimes suggested) or the increased number of competent observers. Still,
the occurrence of solitary gulls well beyond the limits of their normal winter
quarters,which generally do not extend to the tropics, staying for months in
succession on the same beach of Aruba, is remarkable. After all, the leeward
coast of Aruba, where all observations were made, with its clear and shallow
waters and sandy beaches seems to be the only place in the South Caribbean
Netherlands Antilles, if not in all South Caribbean islands, which is regularly
frequented by flocks of wintering gUlls, usually Laughing Gulls without
exception (Voous 1975: 135-137). Probably the situation of Aruba, on the
continental shelf, easily reached from the Caribbean coast lines of Central
America and Colombia, and the abundance ofsmall fish make the southwest
coast of Aruba most favourable for exceptional coastal bird species turning
up and staying for some time. Incidentally, the appearance of the Great
Black-backed Gull L. marinus by about 24 Nov. 1971 is likely to have been
influenced by the passing of the Tropical Storm Laura (developed in the
southwest Caribbean on 12 Nov.; Nat. Summary Climatological Data, U.S.
Weather Bureau, November 1971: 19-20), which may have swung an already
exceptionally southward drifted gull from the Gulf coast or northern Cuba
all along the Middle American coast down to tropical South America.

   Even more remarkable is the repeated occurrence of Lesser Black-backed
Gulls L. Juscus in Aruba, as, in contrast to the other gulls, these are Old
World breeding birds. Also unlike the other gulls they are long-distance
migrants, most of them wintering in subtropical and tropical Africa. Whether
the birds appearing in Aruba have been drifted across the tropical Atlantic
Ocean, or whether they had previously straggled to the North American east
coast coming from or passing Iceland, where this species has recently settled,
and then followed their southerly migration route, will always remain
obscure. But its increasing, occurrence within the limits of the West Indies,
where it was unknown before being observed and collected at St. Martin,
northern Lesser Antilles, 8 Nov. 1965 - 13 Jan. 1966 (Voous & Koelers 1967:
127-128), makes one wonder if perhaps this species is building up an as yet
unknown breeding nucleus in eastern North America where it is recently
more frequently seen than at any time after it had been reported there for
the first time by about the middle of this century. Whereas the specimen
from St. Martin clearly belonged to the light-mantled Atlantic race graellsii,
at least one bird from Aruba appeared on the colour-print too dark for that
race; however, any attempt to subspecific identification must be considered
82                                NORTHERN GULLS IN ARUBA                             [Ardea64

  It should be stressed that of the four species of northern gull mentioned
above only the Herring Gull L. argentatus (once in Trinidad, and seen
between 31 Oct. 1959 and IO Jan. 1960, Aruba; Voous 1965: 221) and the
Ring-billed Gull L. delawarensis (once seen in Trinidad) have ever been
recorded from within the limits of South America (ffrench 1974, de
Schauensee .1966).

  Het voorkomen van noordelijke meeuwen op Aruba, Nederlandse Alltillen.
  Recente waarnemingen van noordelijke meeuwen als nieuwe dwaalgasten op Aruba worden
besproken. Zij hebben betrekking op de Grote Mantelmeeuw (2 x), Kleine Mantelmeeuw (4 x),
Zilvermeeuw (2 x) en Ringsnavelmeeuw (I x). De verschuning van de Grote Mantelmeeuw op
24 nov. 1971, die tot in feb. 1972 op Aruba bleef hangen, wordt in verband gebracht met een
mogelijke verplaatsing van deze vogel door de tropische storm Laura (14-21 nov. 1971). Van de
genoemde meeuwen werden aileen de Zilvermeeuw (Aruba, I x) en de Ringsnavelmeeuw
(Trinidad, I x) op een van de Zuid-Caraibische eilanden vastgesteld. Van hen zijn a\leen de
Kleine Mantelmeeuwen lange-afstandstrekkers. Zij zijn ook de enige die niet in de Nieuwe
Wereld, maar langs de West-Europese kust broeden. Hoe zij op Aruba terecht kunnen zijn
gekomen is onbekend, maar de theorie wordt geopperd van een mogelijk verband met een
recente uitbreiding van het broedgebied in de noordelijke Atlantische· Oceaan· en daarmee
samenhangende veranderingen van de trekroute van sOmmige van deze vogels.

ffrench, R. 1974. A guide to the birds of Trinidad and Tobago. Narberth, Penn. (Livingstone).
Schauensee,. R. Meyer de, 1966. The species of birds of South America. Narberth, Penn.
Voous, K. H., 1957. The birds of Aruba, Cural;ao, and Bonaire. Stud. Fauna Cural;ao andother
         Caribb. Islands 7 (29): 1-260.
---,1965. Check-list of the birds of Aruba, Cural;ao, and Bonaire. Ardea 53: 205-234.
- - - & H. J. Koelers, 1967. Check-list of the birds of St. Martin, Saba, and St. Eustatius. Ar-
         dea 55: 115-137.

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