TULP I (1998) Reproduction of Kentish Plovers Charadrius alexandrinus and Ringed Plovers Charadrius hiaticula on three Dutch Wadden Sea Islands in 1997. LIMOSA 71 (3): 109-120.

Kentish Plovers and Ringed Plovers breed mostly in coastal areas in The Netherlands. Both species, but partcularly Kentish Plover, have shown considerable declines in The Netherlands, especially in the Wadden Sea. In the breeding season of 1997, a study was carried out on factors that determine breeding success of Kentish and Ringed Plovers on the islands of Terschelling, Vlieland and Griend in the Dutch Wadden Sea. In total 33 Kentish Plover and 24 Ringed Plover nests were found. Hatching success was 30% and 36% respectively. Compared to data from other sites, these percentages are not extremely low. The main cause of nest loss was predation, followed by flooding of nests. The first eggs were laid in late April and the last nests were started in late July.
      Breeding success amounted 0.25 and 0.40 fledglings per pair of Kentish Plovers on Terschelling and Griend respectively. Ringed Plovers raised 0.40 fledgling per pair on Terschelling and 0.67 on Griend. Considering that the reproduction necessary for a stable population amounts to 0.8 and 0.9 fledgling per pair per breeding season for Kentish and Ringed Plovers respectively, the observed breeding success is too low to compensate mortality.
      On the North Sea beach of Terschelling most chicks died shortly after hatching. The chicks that made it until fledging were all born on the south side of the island, adjacent to the mudflats. Growth rates of chicks that grew up on the south side of the island matched with measurements on growth rates of Kentish Plover chicks in Hungary. The growth of Ringed Plover chicks that were born on the North Sea beach and stayed alive showed retarded growth compared to chicks in England. On the Wadden Sea side, Ringed Plover chicks grew much faster. A combination of food availability and disturbance is the most likely cause for this reduced growth and low survival on the beach. Visitors on the beach probably prevent the families with chicks to exploit the best feeding areas close to the water and force them to stay on the higher drier areas close to the dunes with lower food availability. Apart from this, the presence of visitors reduces the amount of foraging time, since when the parents are alarming, the chicks refrain from feeding. Measures aimed at maintaining the breeding population on the islands would be most efficient when focusing on creating disturbance- free breeding habitat on the Wadden Sea side of the islands, rather than safeguarding the breeding habitat for plovers on the North Sea beach.

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