Tuesday 6 January 2015

Wilson's Plover and its subspecies.

Wilson's Plover Charadrius wilsonia is a stocky 'ringed' plover with a heavy black bill which lives almost entirely on the coasts of southern North America, Central America, the Caribbean Islands and northern South America.

Adult male Wilson's Plover Charadrius wilsonia wilsonia in breeding plumage. Galveston, Texas, USA. April 2013.

It is currently generally divided into four subspecies; C.w.wilsonia - a migrant population that breeds in eastern USA, south from Virginia along the Atlantic coast and Gulf of Mexico to Belize and including the Caribbean Islands and winters in Florida, along the western Gulf coast, the Caribbean, and South America along the coast south to North-East Brazil (includes C. w. rufinucha that occurs in the Bahamas, Greater Antilles and some of the Lesser Antilles); C.w.beldingi - less migratory, breeding along Pacific coast from southern California to Panama and moving as far south as northen Peru when not breeding; C.w.cinnamominus - sedentary, breeding along the north coast of South America including southern Carribean Islands from Colombia to French Guiana; C.w. crassirostris - a sedentary population in North-East Brazil.

This last subspecies crassirostris was only accepted in 2008 and thereby hangs a tale.

Adult female Wilson's Plover Charadrius wilsonia wilsonia in breeding plumage. Galveston, Texas, USA. April 2013.

Up until 2008 only three of the above subspecies were recognised namely wilsonia, beldingi and cinnamominus. In Atualidades Ornitológicas 142 in that year Brazilian ornithologists Grantsau and Lima proposed the existence of a new subspecies in Brazil and called it C. w. brasiliensis. They pointed out that the species was not simply a non-breeding visitor to Brazil, but that it bred in small numbers along the coast of Brazil from Amapá in the north where Brazil borders French Guiana south to Northern Bahia.

First non-breeding Wilson's Plover Charadrius wilsonia, Crandon Beach, Biscayne Island, Florida, USA. November 2012.
It was generally accepted that this referred to a different subspecies bringing the accepted total to four however the name offered by Grantsau and Lima C. w. brasiliensis was not accepted as the name crassirostris had previously been assigned to the same population although this name had been absorbed into wilsonia and then cinnamominus. Grantsau and Lima argued that the name cinnamominus was invalid as the type specimen no longer existed and the description was made from a specimen with no proper details of its provenance but this has not been generally accepted and so, as is the way with these things, the new race was called crassirostris and attributed to Spix 1825.

(Behind) Juvenile/first non-breeding Wilson's Plover Charadrius wilsonia. (In front) Semipalmated Plover Charadrius semipalmatus. Crandon Beach, Biscayne Island, Florida, USA. November 2012
This link will take you to the paper in Atualidades Ornitológicas It is written in Portuguese but you will be able to see the photographs and plates.

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