Breeding seabirds in the Zeeland delta
The Kentish plover, little tern and common tern nest on bare, open land in the coastal zone. These species are threatened, because such land is becoming scarce. The Kentish plover is currently declining further; by contrast, the common tern is increasing.
Trends in the Kentish plover
The Kentish plover is a pioneer species that nests on bare, open land along the coast, such as beach plains, saltmarshes rich in shellfish, and young dunes. In recent decades this species has been declining in the Netherlands and northwestern Europe. Currently there are still 1000 breeding pairs, 350 of which are in the Netherlands. With 230 pairs the Delta area is one of the last strongholds of the Kentish plover in northwest Europe, but since 1979 the species has been declining in the Zeeland delta too.
The reason for the decline is a decrease in the natural dynamics. Various measures have resulted in there being fewer open areas along the coast than there would be naturally, and these areas are becoming more vegetated. This reduces the areas suitable for the Kentish plover to nest in. Beaches are among the last dynamic areas where this species occurs, but beaches also attract tourists. Research done in the German area of the Waddenzee (Wadden Sea) has shown that recreation has a negative impact on the establishment and breeding success of this species (Schulz 1991; Schulz & Stock 1992, 1993). Small wonder that the Kentish plover has all but disappeared from the Dutch beaches, which are open to the public.
Trends in the little tern
The little tern also nests on shelly beaches or sand flats that are bare or sparsely vegetated. At the start of the 20th century there were still about 1000 breeding pairs in the Netherlands, but poisoning from chlorinated hydrocarbons resulted in the number declining to about 100 in the 1960s. Poisoning is no longer a problem. While the Delta Works were being constructed the little tern profited from the nesting habitats that became temporarily available, but it disappeared when these areas became overgrown. The little tern is also suffering from the increase in beach recreation.
Trends in the common tern
Roughly a quarter to a third of the common terns breeding in the Netherlands occur in the Delta area. The common tern is less choosy than the Kentish plover and little tern. It nests on beach plains, saltmarshes and artificial islands. It, too, suffered from poisoning from chlorinated hydrocarbons in the 1960s, but in the Delta area is now recovering. But because many suitable nesting areas have been lost to recreational uses, it is doubtful whether the high numbers of the 1930s will be regained.
Kentish plover, little tern and common tern are on the Red List of birds.
Technical note
Technical note
The graph shows the number of breeding pairs of the Kentish plover, little tern and common tern, based on censuses by the RIKZ in the Zeeland delta. Since 1979 the Kentish plover has declined significantly and the common tern has increased significantly. There has been no significant change in the little tern.
References
References
- Schulz, R. (1991). Der Einfluss von Störungen auf die Verteilung und den Bruterfolg des Seeregenpfeifers Charadrius alexandrinus, L . 1758 im Vorland von St.Peter-Bohl. Diplomarbeit, Mathematisch-Naturwissenschaftliche Fakultät des Christian-Albrechts-Universität zu Kiel.
- Schulz, R. en M. Stock (1992). Seeregenpfeifer und Touristen. Landesamt für den Nationalpark, Tonning/WWF-Wattenmeerstelle, Husum.
- Schulz, R. en M .Stock (1993). Kentish Plovers and tourists: competitors on sandy coasts. Wader Study Group Bulletin 68, suppl.: pag. 83-91.
- Tulp, I (1998). Reproductie van Strandplevieren Charadrius alexandrinus en Bontbekplevieren Charadrius hiaticula op Terschelling, Griend en Vlieland in 1997. Limosa 71: pag. 109-120.
- Meininger, P.L. en R.C.W. Strucker (2002). Kustbroedvogels in het Deltagebied in 2002. Rapport RIKZ (in prep).
- Bijlsma,R.G., F. Hustings en C.J. Camphuysen (2001). Algemene en schaarse vogels van Nederland (Avifauna van Nederland 2). GMB Uitgeverij/KNNV Uitgeverij. Haarlem/Utrecht.
