The Future of the Oostvaardersplassen: Ecological Corridors and Predation

by | Mar 3, 2018 | Conservation, Ecological Restoration, Reintroduction

The ‘no interference’ controversy in the famous Oostvaardersplassen sparked new conflicts between the Dutch Forest Department and animal welfare organisations and the general public. In February 2018, 1062 animals died in the reserve because of a lack of food combined with the harsh weather conditions. In total 858 red deer, 184 konik horses and 20 heck cattle died. 993 animals were shot because they were not expected to survive the winter. 60 animals died of a ‘natural’ cause, starvation in this case, according to a report of the Forest Department.

The animals in the nature reserve Oostvaardersplassen are now receiving supplemental feeding after foresters were threatened and members of the public started feeding the animals illegally.

We have translated a comprehensive article about the recent animal welfare and conservation situation in the famous Oostvaardersplassen. Some of the specialists involved in research and development of the nature reserve have been interviewed. True Nature Foundation does not necessarily agree with the opinions expressed in the article.

Development of healthy ecosystems is dependent on wildlife densities and complete food chains with all trophic levels present. Vegetation development is grazer density dependent. The current situation is not natural because the area is confined and large predators are lacking. Mass die-offs don’t have to take place when the ecosystem is intact.

In the current situation:

  1. The populations of large grazers increased, exceeding the carrying capacity of the area;
  2. Overgrazing is a result of over-population;
  3. There are no natural predators that regulate grazer numbers;
  4. The Oostvaardersplassen is an isolated area without possibilities for migration and dispersal.
The solutions can be derived from the problems above. We propose an ecological approach:
1. Active management and intervention (Short-term population management strategy);
2. Habitat corridors to connect the isolated Oostvaardersplassen to other nature areas (Holsterwold, Utrechtse Heuvelrug, Veluwe, Germany)(Mid to long-term strategy);
3. Allowing predation (Mid to long-term strategy).



Translated from Dutch:

Disagreement about Oostvaardersplassen

The Dutch Forest Department (Staatsbosbeheer) will be feeding large grazers in the Oostvaardersplassen until the end of the winter. This decision was taken by the Provincial government of Flevoland because of increasing social unrest about the situation of the animals.

Will this supplemental feeding be a permanent policy, should game management be changed or should the general public get used to the fact that large numbers of animals die in winter?

The biological preconditions for nature development seemed ideal in the Oostvaardersplassen: research by University of Groningen Professor in Ecology Han Olff showed that the land in the current nature reserve is up to three times more productive than a normal Frisian pasture with a comparable soil type. This exceptional fertility caused an explosion of flora and fauna after the area was drained.

“At the beginning of the seventies, it became clear that a beautiful nature reserve was developing here”, says Frank Berendse, Emeritus Professor of Nature Management at the University of Wageningen (WUR).

Southern Flevoland was reclaimed at the end of the sixties. Reeds were sown from the air at many places in the new polder. This promoted further land reclamation via evaporation. The area currently known as the Oostvaardersplassen is low-lying. It turned out to be too wet at that time and was therefore ignored. As a result, nature temporarily got a free hand here.

The area quickly developed into a swamp, attracting an overwhelming wealth of birds. For example, the grey goose reappeared – a species that had not been seen in the Netherlands for a long time. Under pressure from public opinion, the marsh area was expanded in the 1970s with some 2,400 hectares of intended agricultural land, which had already been drained, but had not yet been cultivated.

In the decades that followed, the idea arose that nature should be given space in the Oostvaardersplassen, with as little intervention by man as possible.

No interference

Oostvaardersplassen nature reserve is managed by Dutch Forest Department, which continued a policy to let nature go its own course for decades. The water levels in large parts of the Oostvaardersplassen were allowed to fluctuate, grazing was not controlled and animals were not fed during the winter. This was linked to ongoing scientific research into the conservation of the habitat of the large grazers in the area and the effects on their environment.

Incidentally, changes were made to the landscape: water plains were dug out and a connection was made with the Lepelaar (Spoonbill) lakes.

That non-interference policy laid the seed for a conflict between objectives that seem to be diametrically opposed: nature should get free rein in the Oostvaardersplassen as much as possible, but the big grazers must also survive – if necessary with the help of Staatsbosbeheer, which was first needed in the winter of 2010.

Wet and dry

The Oostvaardersplassen are roughly divided into a wet section – wetland – and a dry part, where the grazers are living. “The important natural values ​​are not in the dry, but in the wet part,” says Berendse, who sees the heck cattle, konik horses and red deer mainly as “unwanted frills” from the Oostvaardersplassen.

“The value for nature in the wet part is indisputable, where you will find the great egret and the spoonbill, the bearded reedling, the water rail and the Eurasian bittern – you name it”, says Berendse. “Before the large grazers were released, the dry part was also fairly rich in all sorts of special species, such as woodcock, roe deer and nightingale, but they have now completely disappeared as a result of grazing. Biodiversity has declined dramatically.”

You could take out those big grazers and put them somewhere else, says Berendse. The dry part of the Oostvaardersplassen is already sinking and shrinking. If you remove the dykes that surround the swamp area, a much larger wet swamp is created.

“I think that the grazers can best give way to the great value of that large wetland in order to get a truly natural area.” The Marker Wadden, an area with ‘natural islands’ that is now being developed, can be added to the area, Berendse thinks.


The spiritual father of the Oostvaardersplassen, the now retired ecologist Frans Vera, thinks very differently about the usefulness of the grazers.

Vera sees the wild cattle, horses and deer as the engineers of the landscape: they were introduced to prevent the higher parts of the nature reserve from becoming overgrown. They eat plants such as grasses and nettles, giving prickly bushes (such as hawthorn and blackthorn) a chance to grow. Once those thorns have developed to a size large enough to keep grazers away, they offer shelter to young trees that would otherwise be eaten.

“The intended result is a varied and park-like landscape that fits well with what we see as an attractive form of nature in the Netherlands.”

Fertile soil

Frank Berendse seriously doubts whether that landscape will actually come. “In territory with a rich food supply, such as the Oostvaardersplassen, that can not really happen.”

That view is supported by recent research by one of his PhD students, Perry Cornellissen, who studied the effects of large grazer populations on the establishment of trees. This study showed that the spine bushes do not come: the seedlings are overshadowed by the surrounding vegetation or they are eaten away at an early stage.

“In the current situation we have a vast grass plain”, Frans Vera argues. “Will they get spine bushes there?” “Yes, but they do not come naturally, that takes time.” And maybe they will not come in the end, because the soil in the Oostvaardersplassen is so fertile that it supports so many animals that the bushes do not get the time to develop spines that are big enough to protect the trees. In that case you have to adjust those ideas.”

‘Not used to’

“We are not used to the extreme fertility of the Oostvaardersplassen in the Netherlands, because all the fertile soil here has been put into use for agriculture”, says Vera. “All sorts of unforeseen things happen in that nature reserve.”

This un-Dutch unpredictability is “an attack on our fixed ideas, and nobody likes to give up those ideas,” says Vera. He still thinks that nature should be left to its own course. “Or, well, you have to expand the area: the bigger, the better.”


Although Berendse and Vera fundamentally disagree about the role of the large grazers in the landscape, they find each other when it comes to the usefulness of supplementary feeding or the ‘preventive shooting’ of hungry ungulates that probably will not survive the winter.

“Berendse calls these measures a” deferred form of animal abuse “. “It all seems very animal-friendly, but the natural adaptation process to the local living conditions, including harsh winters, is seriously disrupted and delayed.”

On the one hand, it is important that the numbers of large grazers are in balance with the food supply, says Berendse. “That balance can only arise if animal species have the opportunity to adapt to their environment.” Moreover, during a harsh winter a strong natural selection takes place: animals that are better adapted, survive. That process is also visible. “Since the introduction of the Heck cattle in 1983, hereditary changes have taken place quite fast.”

Supplying or creating additional shelter disturbs that process. “You get more animals, which are less adapted, and the problem only gets bigger. In that situation, even more than now, you have to take all sorts of zoo-like measures.”

Annual rhythm

Vera thinks that attention should be paid to the natural course of the seasons, which determines the rhythm of animal life. The whole year is actually dedicated to preparing for the winter. “We never see media appear in the summer when all those animals get their fat supply. When it gets cold, they become thin, and people pretend this is a completely unnatural phenomenon.”

He is not impressed about the social criticism. “The Oostvaardersplassen are managed, veterinarians are associated with Staatsbosbeheer and there are protocols.”

‘Incorrect experiment’

In the fuss about the mortality among the grazers, there are also parties that wonder whether you can speak of a real nature reserve. “The Oostvaardersplassen as a whole must be reconsidered,” says Caroline van der Plas of Team Agro NL, an action group of farmers and horticulturists who have their own PR and promotion, because they are tired of the negative attention for agriculture.

“We want nature in the Netherlands to go its own way, but that is not possible at all,” she says. “An experiment like the Oostvaardersplassen does not belong here, the Netherlands is a big city, and the Oostvaardersplassen are just an animal park, but it is not a natural situation: animals can not leave to find food elsewhere.”

Van der Plas and the farmers she represents see a double standard, and that stings. “When farmers treat their animals like this, they have to come to court and their businesses are closed. The Oostvaardersplassen is a toy for nature lovers who find it very difficult to admit that the experiment has failed and that we just have to treat animals in the manner prescribed by law.”

Vera objects and states there is always a limit to a nature reserve, such as a mountain ridge, a river or another climate zone.

“A period with lack of food – in our regions the winter and in the tropics drought – is always a correction on the population numbers”, he concludes. The retired ecologist emphasises that the better wild animals are doing, the greater the number that die.

“Now the conclusion comes down to reducing large grazers populations, to almost decimate them so that the absolute numbers of dead animals does not hurt people anymore. This is very sad for nature”, says Vera.

“Apparently, we can not accept that nature is different from a horse riding school or a farm.”


Photo: By EM Kintzel, I Van Stokkum (CC BY-SA 3.0)


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