7A Sanderlings Calidris alba ready to fly home
Sanderling Calidris alba: ready to fly home
Sanderlings breed in Arctic regions of Alaska, Canada, Greenland and Russia and spend the winter on the beaches of Europe, Africa, Asia, New Zealand, USA and South America. En route to the Arctic in spring they moult into breeding plumage and gain weight in order to be able to fly the huge distances.
Females are slightly bigger than males. According to Prater et.al 1977 (Guide to the Identification and Ageing of Holarctic Waders, BTO Guide 17) males in breeding plumage have a black/red-brown back while females are black/greyish above.
Two subspecies are recognized, nominate Calidris alba alba which breeds from NE Greenland to and including Taimyr, N Russia and Calidris alba rubidus which breeds from NE Siberia to and including North Canada (Engelmoer, Meinte & Cees S.Roselaar, 1998, Geographical Variation in Waders).
The upperparts of the short-billed nominate C.a.alba are said to be reddish-brown or brownish in breeding plumage whereas the longer-billed Nearctic C.a.rubidus have more greyish-white upperparts.
The above clues are rather confusing as one can be tempted to think that a black/grey bird, a female C.alba according to Prater at al, is in fact a C.a.rubides! Pictures taken at the breeding grounds of a pair in NE Greenland show two reddish birds which seems to contradict Prater et al that only males are reddish-brown!
The pictures below have been taken at high tide roosts in the Dutch Rhine-Meuse delta where Sanderlings peak in numbers during April and May. Formerly it was thought that birds arriving in mid-May were of Siberian stock whereas the winter population was Greenlandic. Recently, Reneerkens et al in their ongoing studies on Sanderlings cast doubt on the presence of Siberian Sanderlings in NW Europe however accept the possibility of birds of Nearctic origin being on their way home to Ellesmere Island during May. Perhaps this explains why some of the birds in the pictures look like Canadian C.a.rubides !
Information on the present Sanderling studies and the used colour-ring schemes can be found here:
the first results have been published in the Wader Study Bulletin vol. 116, no 1, April 2009 pp.2-20: Sanderlings using African-Eurasian flyways: a review of current knowledge by Jeroen Reneerkens et al.
10 Sanderling Calidris alba 17052007 0129 Westercheldt, The Netherlands c NDvS
all pictures copyright NORMAN DEANS VAN SWELM (NDvS) in The Netherlands
CLICK TO NAVIGATIONPAGE 18 Nov 2021