Oostvaardersplassen — Dutch 'New Wilderness' Rewilding Experiment and the 2017–18 Winter Die-Off (Cautionary Case)

The Oostvaardersplassen (c. 5,600 ha, Flevoland, Netherlands; Ramsar-listed and a Special Protection Area) is a former polder left to nature. From the 1980s–90s Heck cattle, Konik horses and red deer were introduced under a non-intervention policy intended to mimic wild grazing. Populations grew, e.g. in 2011 about 3,300 red deer, 1,150 Koniks and 350 Heck cattle, with no large predators, fenced boundaries and planned wildlife corridors (e.g. towards the Veluwe) never realised.
After the harsh winter of 2017–18, press and academic accounts report that more than 3,000 large herbivores died (WHYY puts this at about 60% of the large grazers), triggering public protests, arrests of people feeding animals and a political crisis. The Van Geel commission advised moving from rewilding to active management, and the 2018 covenant between the Province of Flevoland and Staatsbosbeheer replaced non-intervention with population limits (WHYY cites a ceiling of about 1,100 large grazers), culling, relocation of horses and supplementary feeding.
Outcomes were mixed: the reserve created open grassland and supported spoonbills, white-tailed eagles (first breeding in 2006) and other waterbirds, but vegetation diversity declined and small grazer populations disappeared. Exact mortality figures differ between sources and should be treated as approximate. The case shows the welfare, governance and ecological risks of closed-system rewilding without natural population regulation.

Read the full analysis: https://whyy.org/segments/the-netherlands-grand-rewilding-experiment-gone-haywire/