ELZERMAN S (2007) Social roosting of Grey Wagtails Motacilla cinerea at Hendrik-Ido-Ambacht. LIMOSA 80 (1): 26-31.

A winter roost of Grey Wagtails was discovered on 25 November 2004 at IJsselmonde (Rotterdam), Zuid- Holland, The Netherlands. The roost consisted of a small reed bed (approximately 8 x 20 m), located in a ditch at the edge of a village (Hendrik-Ido-Ambacht). The number of wagtails and their behaviour was surveyed during evening counts in the winters of 2004/05 and 2005/06. The number of GreyWagtails peaked in the beginning of November (37 birds on 6 November 2005). Numbers declined after November and were relatively stable throughout the winter (Fig. 1). A second, but less pronounced, peak occurred in early spring. Autumn and spring peaks coincide with the main migration periods. Most of the Grey Wagtails landed directly in the reed bed, although others used the last moments of daylight to forage in the immediate surroundings. Birds arrived from different directions, mostly alone, but also in groups of two to three (maximum five). Birds tended to arrive later in themiddle of the winter when the days are shorter (Fig. 2), presumably because they needed more foraging time to obtain enough resources to survive the longer nights. An influence of temperature or other weather variables on behaviour of the birds could not be detected.
      In Table 1 an overview of winter roosts in the Netherlands is provided. Most roosts seem to be located in scrubs, although the largest roosts are found in reed beds. The absence of reports of roosts from the eastern and southern part of the Netherlands is remarkable since many GreyWagtails winter there.

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