Broedresultaten van kokmeeuwen in Nederland in 1997 = Reproductive success of Black-Headed gulls in the Netherlands in 1997

The Black-headed Gull population in The Netherlands, as in other parts of Europe, has seriously declined since the 1980s. The decline has been noted both at coastal and mainland breeding sites. The reasons for the general decline are not known. Therefore a monitoring programme was established to measure breeding results of Black-headed Gulls in six Dutch colonies in 1997. Remarkable differences were found in hatching success and breeding success. Hatching success was high (75- 90%) in the three northern colonies situated in or near the Wadden Sea, whereas in all other colonies hatching success... Mehr ...