Boere G.C., Roselaar C.S. & Engelmoer M.E. (1984) The breeding origins of Purple Sandpipers Calidris maritima present in the Netherlands. ARDEA 72 (1): 101-109

Only some hundreds of Purple Sandpipers Calidris maritima winter in The Netherlands. A relatively large proportion (up to 30%) is found on Vlieland, one of the Frisian islands in the Waddenzee, where trapping occurred between 1971 and 1976. Of these birds we used measurements, weights, moult data, and ringing recoveries to obtain a better understanding of the origin and migration of the Dutch winter birds. Measurements of museum skins from known breeding areas were compared with birds trapped alive as well as with skins of birds wintering in The Netherlands. A great correspondence in measurements between birds breeding in Canadian arctic, those of Novaya Zemlya and Vaygach (USSR), and the winter birds of The Netherlands was found. These populations all have an average wing length of 128-130 mm (skins) or 130--132 mm (fresh) in ?? and 132-136 (skins) or 136--139 (fresh) in ??, whereas only Icelandic breeding birds have longer wing lengths while all other breeding populations are smaller-sized. Most winter birds arrive in The Netherlands after completion of primary moult. Some moulting small-sized birds were trapped in autumn. These probably belong to Greenland or Scandinavian breeding populations and are similar in size and moult schedule with birds wintering in Scotland. No mid-winter weight peak was found in the wintering population of the Purple Sandpiper, which is similar to the Scottish situation (Atkinson et al. 1981). Apart from birds storing fat prior to spring migration, weight changes during winter as well as differences in weight between Purple Sandpipers wintering in The Netherlands and Scotland are probably a consequence of the occurrence of birds of different size. Ringing recoveries of Dutch birds support a Canadian breeding origin, although a Russian one cannot be excluded.