TEMPORAL AND SPATIAL EXPANSION OF THE EGYPTIAN GOOSE ALOPOCHEN-AEGYPTIACUS IN THE NETHERLANDS, 1967-94

In this paper, the temporal and spatial expansion of the Egyptian goos e in the Netherlands are described and analysed. The species bred near The Hague for the first time in 1967. In 1983 a second settlement dev eloped in Drenthe. Both settlements expanded. Together, they contained about 1340 breeding pairs in 1994. For both settlements a linear rela tionship exists between the square root of the area occupied and time. In both cases, population growth is exponential. The bird behaves as a resident species. Thus, in winter numbers in The Netherlands also in crease exponentially. The Egyptian goose seems to be sensitive to seve re winters, which cause a high mortality. The observed velocity of ran ge expansion is compared with the velocity as calculated with the expa nsion model of Van den Bosch et al. (1990). The observed velocity was about 3.0km per year, which is about 20% lower than expected, but not significantly different. Population growth was estimated using a proje ction matrix. In the first 10 years after its settlement near The Hagu e, the actual population growth was larger than the calculated growth. There is evidence for good breeding success during the first years du e to mild winters between 1972 and 1978. In the second settlement, Dre nthe, the same rapid population growth occurred. Here, a low but regul ar influx of birds from a nearby city park was probably the main facto r. In the near future, further temporal and spatial expansion can be e xpected, in the direction of Germany and Denmark in the east and Belgi um and France in the south. Towards the east the severity of the winte rs might limit further range expansion, possibly coinciding with the 0 degrees isotherm in January.