jueves, 24 de julio de 2008

Gull taxonomy

El lunes me llegó el último número de British Birds, en el que se publica un artículo que será de referencia para los gavioteros incansables. A continuación pego el resumen de dicho artículo, sacado de un foro.
Entre otras cosas de interés, la confirmación del taxón Larus fuscus fuscus como subespecífico de Larus fuscus ("indiferenciable en el campo"), y la afirmación de las 2 subespecies de Larus argentatus que manejamos actualmente.
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1. Caspian Gull (L. cachinnans) is monotypic species (no subspecies). There are no records of Caspian Gull in North America. However, the AmericanOrnithologists Union (AOU) considers the Caspian Gull as a distinct speciesas reported under Yellow-legged Gull (L. michahellis) in the 48th Supplement to the Check-list (Auk 124(3):1109- 1115,2007).
2. Lesser Black-backed Gull (L. fuscus) with 6 subspecies: nominate fuscus,intermedius, graellsii, heuglini, taimyrensis, and barabensis. Some believethat Baltic Gull (nominate fuscus) should be a separate species based on"plumage and structural characters, moult cycle, foraging and migrationstrategies." However, mtDNA show a continuous gradation (paralleling mantle colour) from graellsii through intermedius to fuscus, "suggesting little ifany reproductive isolation." The field identification of Baltic Gull "is probably impossible, except on the basis of geographical location." Although taimyrensis is treated as a subspecies of the Lesser Black-backed Gull, theauthors state that it "may be best synonymised with heuglini or be regardedas a transient heuglini x vegae population.
3. American Herring Gull (L. smithsonianus) with 3 subspecies: nominate smithsonianus, vegae, and mongolicus (no North American records).The authors accept that others recognize two or three species in thiscomplex. In contrast, the American Ornithologists Union (AOU) considers smithsonianus and vegae as part of the argentatus species group in number
4. Herring Gull (L. argentatus) with 2 subspecies: nominate argentatus and argenteus. This is a large reduction for a species that until recently hadabout 12 subspecies as in P.J. Grant's (1986)Gulls: a guide to identification.
5. Yellow-legged Gull (L. michahellis) with 2 subspecies: nominatemichahellis and atlantis. Other populations may deserve subspeciesdesignation. The 1998 AOU Check-list split Yellow-legged Gull(cachinnans) as a separate species from the Herring Gull complex. The 48thSupplement to the AOU Check-list in 2007 changed the specific scientificname of Yellow-legged Gull from cachinnans to michahellis based on different plumage morphology, nesting behavior and mtDNA. The 48th Supplement accepted atlantis as the subspecies in North America based on a specimen from Quebec. Nominate michahellis probably occurs inNorth America, but is unconfirmed to date.
6. Armenian Gull (L. armenicus) is monotypic.
Article : Collinson, J.M., Parkin, D.T., Knox, A.G., Sangster,G., and L. Svensson. 2008. Species boundaries in the Herring and LesserBlack-backed Gull complex. British Birds 101(7):340-363.

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