De Nijlgans Alopochen aegyptiacus in Drenthe in 1980-91

The Egyptian Goose was observed for the first time in the province of Drenthe in January 1980. The settlement in northern Drenthe in 1981 was the beginning of a success story, with ever increasing numbers (fig. 1) and colonisation of other parts of the province since 1988 (fig. 2). The Egyptian Goose is mainly restricted to the breeding areas in midsummer and more widely dispersed in winter (fig. 3, 4). Mean flock size in 1980-91 was 7.4 (n=923 flocks), increasing from 2.5 in 1980-82 to 3.5 in 1983-85, 6.0 in 1986-88 and 8.2 in 1989-91. Rocks of 1-10 birds were most often observed (82.7%). Seasonal trends in flock size are depicted in fig. 5: smallest flocks were noticed in summer, largest flocks in September. A variety of breeding places was used: on the ground, with or without cover, under bushes, in trees, in nestboxes and in nests of Carrion Crows or Magpies (sometimes after eviction of the rightful owners). Breeding was observed from mid-January to late June. Average number of goslings in successful pairs was 5.3 (n=31, range 1-14). Most breeding places are evacuated in favour of suitable foraging sites soon after the young are able to fly.