ENS BJ, BOM RA, DOKTER AM, OOSTERBEEK K, JONG J DE& BOUTEN W (2014) Using the UvA Bird Tracking Systeem (UvA-BiTS) in Oystercatcher Haematopus ostralegus research. LIMOSA 87 (2): 117-128.

This paper reports on new discoveries and new possibilities due to the deployment of the UvA Bird Tracking System (UvA-BiTS; Bouten et al. 2013) in our investigations of the behavioural ecology of Oystercatchers. This GPS tracker is powered by solar cells and not only stores GPS locations, but also measurements with a tri-axial accelerometer, which can be used to infer behaviour (Shamoun-Baranes et al. 2012; fig. 4). Since 2008, 72 Oystercatchers were fitted with such GPS trackers.
      Contrary to our expectations, Oystercatchers breeding in the polder of Ameland, where they can feed on earthworms and tipulid larvae, continued to visit the Wadden Sea mudflats throughout the breeding season, just like birds breeding on the saltmarsh of Schiermonnikoog (Fig. 1). We were equally surprised to learn that the breeding populations on both islands included migrants. Whereas many breeding birds remained within 10 km of the breeding territory throughout the winter (Fig. 2), a minority moved much greater distances to a clearly distinct wintering area (Fig. 4). Fidelity to a particular wintering area was high, irrespective of distance moved.
      We also show examples of the potential of UvA-BiTS to address important scientific questions. Young birds must find a good place to learn how to survive and Fig. 5 shows the behaviour of such a bird: it stays for several months in a particular location and then moves to a new location. Once an individual is sufficiently proficient at surviving, it can enter the competition for breeding territories as a club-bird, usually at the age of three years. Figure 6 compares the ranging behaviour of a non-breeder to that of a breeder at the height of the breeding season.

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