TURNHOUT C VAN& VAN ROOMEN M (2008) Trends in phenology of Sanderling Calidris alba in the Netherlands. LIMOSA 81 (1): 1-10.

In this paper we describe phenology, distribution, numbers and trends of Sanderling in the Netherlands. Phenology differs significantly between mudflat areas (in Wadden Sea and Delta) and North Sea beaches. In mudflat areas numbers are highest during spring (May) and autumn (August-October) migration, whereas on beaches most Sanderlings are present during midwinter (Fig. 1, 2). Numbers of Sanderling have strongly increased in the recent decade in the Netherlands,without a clear difference betweenmigrating andwintering populations (Fig. 3). Also, trends within mudflat areas (Wadden Sea and Delta) appear rather similar (Fig. 4). However, trends differ strongly between mudflat areas, where numbers have increased, and North Sea beaches, where they are stable (Fig. 5). Furthermore, within the internationalWadden Sea population trends are different. In Schleswig-Holstein and Niedersachsen numbers are more or less stable, in contrast to increasing populations in Denmark and The Netherlands (Fig. 6). Possible causes of these differentiated trends are discussed. Carrying capacity of Dutch mudflat areas for Sanderlings may have increased as a result of the observed increase in worm stocks. Simultaneously, conditions on the beaches may have been unaltered, or may even have deteriorated because of increased beach nourishment and recreation.

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