The impact of fallow deer (Dama dama) grazing on the biodiversity of a Dutch coastal dune system
Author: Vincent van der Spek
https://doi.org/10.63269/SJL5814
Abstract: In the coastal dune system of Amsterdamse Waterleidingduinen (AWD), the Netherlands, numbers of the once introduced fallow deer (Dama dama) increased exponentially during the late 1990s and early 2000s. Thereby grazing pressure also increased. By the spring of 2016, the density was an estimated 190-220 deer/km². Several studies show that increased grazing pressure has resulted in loss of biodiversity. This was based on longrunning monitoring networks of plant and animal species (including citizen science by volunteers), databases for sightings of plant and animal species, vegetation mapping, data modelling, small-scale field experiments and judgements by independent (inter)national experts. Studied species included mammals, birds, reptiles, butterflies, micro and macro moths, bees, bumblebees, hoverflies, butterflies and plants, as well as vegetation and habitats. Temporal comparisons were used in order to detect changes within the area over time, spatial comparisons for differences between AWD and other, comparable dunes systems with little or no fallow deer grazing. This review summarizes all published papers and reports on this subject up to 2024. These reports are all in Dutch, and therefore this review also makes the conclusions of these publications available for a wider audience. The correlation between increased deer numbers and strongly decreasing numbers of many species (groups) is such that it is justified to conclude that a high grazing pressure has led to significant biodiversity loss, and that strictly protected Natura 2000 habitats are under pressure. Partially based on the impact on biodiversity, the responsible authorities have granted permission for population control of fallow deer since 2016.
