Invloed van recreatie op broedvogelverspreiding in de Amsterdamse Waterleidingduinen

Increasing open-air recreation is putting a strain on nature reserves in The Netherlands. Research is necessary to maintain the delicate balance between recreation and conservation without a decline in diversity. This study investigated the effect of the number of groups of people passing per day along paths on the shortest distance of birds' nesting sites to these paths. It was expected that this distance will be larger if the path is more frequently visited in addition to possible effects of species and vegetation type (landscape). Breeding bird data from the Amsterdam Water Supply dune reserve in 1998, obtained by territory mapping, were combined with data on recreation distribution. The effects of passage frequency, landscape (wood, shrub and open dunes) on the shortest distance from the path of breeding territories of sixteen bird species were evaluated using regression analysis (Tab. 1; Fig. 2). In shrub, the shortest distance between breeding territories and paths clearly increased at higher passing frequencies, both for all species combined and for six species analysed separately. In wood and open dunes, no effect of passage frequency was detected for the combined species, but a significant relation was found in both landscapes for Nightingale Luscinia megarhynchos (positive in both) and Chiffchaff Phylloscopus collybita (negative in woodland and positive in open dunes). In five common species that were represented with at least three territories in all landscapes, shortest distances to the path increased with passage frequency in both shrub and open dunes. In all landscapes. Nightingales responded to passage frequency in all landscapes. Averaged over all bird species, the centres of bird territories were closest to the paths in woodland, and here almost no effects of visitor passage rate were found. It appears that especially in shrub, breeding birds show increased shortest distances to the path with increased passage frequencies of visitors. This effect is also present in some common species that are not known to be very sensitive to disturbance. The method used appears quite suitable for a rather quick application in nature management where decisions have to be made regarding management of recreation pressure.