The goshawk and environmental influences

Goshawks have increased dramatically as a result of the ban on certain pesticides and because they have colonised young forests.

Trends

Because it is a top predator, the goshawk is at risk from the accumulation of environmentally hazardous substances in the food chain. In the 1960s the use of seed treated with organochlorine compounds caused the goshawk population to decline dramatically, to 75-100 breeding pairs. A reduction in the use of these pesticides, coupled with less persecution of goshawks allowed the population to rise: to 1800 breeding pairs in 2000. Numbers are currently higher than before 1950, because more suitable woodland is available and the birds are being persecuted less.

In the 1980s and 1990s, goshawks were found in the forests on the sandy soils in the east, centre and south of the Netherlands, in Flevoland province, and in the forests in the northwest of Overijssel province. In these areas, goshawk numbers have stabilised, and in some areas numbers have even declined somewhat, because locally the supply of food has worsened (see right-hand diagram). Since the 1990s, goshawks have also been breeding in the younger forests and in the west and north of the country; e.g. in the Amsterdamse Waterleidingduinen and in the Wadden region. Numbers are rising sharply in these areas (see left-hand diagram).

Technical note

The data are from the Avifauna of the Netherlands, supplemented with counts from the Ecological Monitoring Network's national network for monitoring breeding birds.

References

• Bijlsma, R.G., F. Hustings en C.J. Camphuysen (2001). Algemene en schaarse vogels in Nederland. Avifauna van Nederland 2. GMB Uitgeverij en KNNV. Haarlem en Utrecht.
• Dijk, A.J. van, L. Dijksen, F. Hustings, D. Zoetebier en C. Plate (2001). Broedvogelmonitoring Project. Jaarverslag 1998-99. SOVON-rapport 2001/03. Beek-Ubbergen.