In the coming year, famine will cause ‘populations to crash’ in the Veluwe, says Gerrit-Jan Spek, coordinator of large game at the Veluwe Wildlife Management Association. “To begin with, among the wild boars. But also among mice, wood pigeons, jays, finches, ducks.”
From his green house in Vaassen we walk straight into the Veluwe woods. A little later we are standing between beeches and oaks. The oaks (the pedunculate oak and the American oak) bear few acorns, according to an initial inventory. Many of the beech trees do indeed carry beechnuts, but most that have fallen so far have turned out to be empty. There is no pulp in it. While the acorns and beechnuts are an important food source for all kinds of animal species.
Scarcity marks the end of an exceptionally rich period, wrote Spek last week on the website Nature Today. Since 2013, beech and oak in the Veluwe have yielded a lot of fruit year after year. That is remarkable, because normally rich and poor years alternate much more.
While he picks up a beechnut from the ground, Spek says that he cannot remember having experienced such a long fertile period before. “I think climate change has something to do with it,” he says, trying to pry open the beechnut with a knife. The flowering of the beech is initiated by a period of at least fourteen days without rain, and a temperature of about thirty degrees. There has been such a period for the past eight years. This year there were warm periods in the spring and summer, but it was also relatively wet.
In the Veluwe, 60 percent of the beech trees have not bloomed. About half of the beech trees that have done so are full of husks, the shell in which the beechnut grows. The other half wears only a limited number of bolsters. Based on this, Spek has calculated that approximately 420,000 kilos of beechnuts must fall on the Veluwe, two to five times less than in recent years.
However, that figure may need to be further revised downwards. In his calculation, Bacon has assumed that the husks contain beechnuts with pulp. But that rarely turns out to be the case with the examples that have fallen so far. It has no pulp at all. “Look, like this one,” he says, prying open the nut in his hand. “Whether this remains the case remains to be seen. Maybe it’s too early for the good nuts.”
All kinds of animal species have benefited from the abundance of beechnuts and acorns in recent years. Spek estimates that the spring wild boar population has doubled to about 5,000 individuals during that time. “They will get another 7,500 piglets, so count on.” Hunters have been shooting more and more wild boars in recent years to keep populations in check. In recent months, there were 5,000, a record.
But it’s not enough, says Spek. For the Veluwe, a target position of a maximum of 1,350 individuals applies. The consequences are clearly visible at this location in the forest. The ground between the trees seems to be bulldozed. Entire tree roots have been rooted out and are exposed.
Bacon also wants to show another place. We walk for a few minutes until we reach a fence. The wild boars can come to our side, but not to the other side. The difference is immediately apparent. The other side is green. There are blackberry bushes up to chest height, with fruits. “And there, raspberry. And dandelions, ground elder, plantain. But what do you see on our side?”, asks Spek. The brown of the bottom predominates. Little grows. Here and there there is a blackberry shoot, but they are no higher than a few centimeters. “The wild boars eat everything, right up to the fence.”
Spek says that after eight nutrient-rich years there are simply too many wild boars for the Veluwe. They put a lot of pressure on many other species. He therefore does not necessarily mind that the populations will collapse. “You can also call it a correction of nature.”
The bad year will also have indirect consequences. The fact that mice have a hard time translates into food poverty for the young of, for example, pine martens and owls. Spek expects that red deer, roe deer and fallow deer will be less affected, because as herbivores they are less dependent on beechnuts and acorns.
On the way back to his house, Spek tells that he is happy with the return of the wolf. The first couple to settle in the Veluwe had their first boy in 2019. This year, two more established pairs joined. Whether the wolves will feast on emaciated wild boars remains to be seen. But Spek expects that they will have more impact on the wild boars when the numbers are drastically lower next year.
Then the swine no longer toss around the bottom everywhere. Which gives other species more chance. “It makes the ecosystem more complete.”
A version of this article also appeared in NRC in the morning of October 13, 2021