ON A cloudy night Anderijn Peeters, a horse-trainer turned environmental protester, parks at a wildlife preserve 30km east of Amsterdam. The back of her van is full of hay. Two more cars of activists pull up, after driving circuitously through neighbouring suburbs to confuse police. Their mission: to feed the wild animals. They sling a bale of hay over the fence. Suddenly, a pickup truck driven by off-duty park rangers speeds into the lot, fog lights blazing. Angry words are exchanged. Soon the police arrive. “This is something I’m prepared to go to jail for,” says Ms Peeters. But the officers leave it at a scolding.

Ms Peeters and thousands of others are up in arms over the government’s policies in the Oostvaardersplassen, a park of 56 square km reclaimed from the sea in the 1960s. In 1995 the forest service adopted a plan inspired by a maverick ecologist, Frans Vera, who wanted to recreate what he believed was the diverse pre-human ecosystem of the Netherlands. Rangers introduced red deer, wild horses and Heck cattle, a German breed created to mimic the ancient aurochs, and let them roam. The result is a landscape of plains, wetlands and forest roamed by thousands of hoofed mammals. Some call it the Dutch Serengeti.

The problems begin in winter. With no predators, the herds are limited only by the food supply. (Mr Vera wanted to re-introduce the wolf, but residents were not enthusiastic.) In December, the animals begin to go hungry and edge up to the fences. Passers-by watch them starve. But the Netherlands has one of the world’s strongest animal-rights movements (the Party for the Animals has five seats in parliament). Its outrage has led the forest service to compromise: rangers now shoot animals that are too far gone. Feeders prefer to intervene.

Activists like Ms Peeters say the Netherlands is too small for a wild park, and that fencing animals in makes humans responsible for them. But Joke Bijl, a forest service spokeswoman, says this is a misunderstanding: all animal populations run up against barriers. A cull may be on the cards, but the animal underground expects to be back next winter, dodging the rangers with bales of hay.