Diependal consists of former sewage fields in the central part of Drenthe, covering 110 ha of open water fringed with reedbeds (Fig. 1). Red-necked Grebes were observed for the first time in 1984; the first successful breeding attempt took place in 1988. Until 1998 0-2 pairs were present (Table 1), but from 1999 onwards the population started to increase. During 1988-1999 Diependal was the most important breeding site for Red-necked Grebes in The Netherlands, with more than 40% of all registered pairs. During 29-30 pair-years in 1988-2001 a minimum of 62% of pairs succeeded in raising young (2.0-2.3 young/successful pair, 1.2-1.5 young/pair). Arrival in the breeding area correlated with the severeness of the preceding winter (Fig. 2).