Near the buzzing urban centre of Randstad, and with the cities of Amsterdam and Haarlem within reach, there’s a remarkable natural retreat. Located on the North Sea coast, the Zuid-Kennemerland National Park welcomes some two million visitors a year. But even within this quiet corner of the Netherlands lies an even more idyllic spot.
This oasis of calm is called Kraansvlak, a varied landscape of about 300 hectares where wet dune slacks alternate with rough grasslands, thick shrublands, patches of pine and deciduous forest, and sandy plains. The area is home to several mammal species, including rabbits, foxes, roe deer and fallow deer.
Hoof and paw prints from all of these species can be seen at one time or another around the lake that lies in the southeast of this fenced-off area. And sometimes they’re joined by other, much larger impressions – hoof prints from horses and other large herbivore that have come to slake their thirst at the lake.
These tracks belong to the European bison – known locally as the wisent – Europe’s largest land mammal. Adult bulls can weigh as much as 800 kilograms, and can exceed 2.5 metres in length. Add a pair of curved horns and a large hump and it all adds up to an impressive beast.
In years gone by, bison roamed widely over western Europe, but habitat loss and hunting drove the species to extinction in the wild nearly a century ago. In 1919, the last wild European bison living in Poland’s Białowieża forest was killed, followed in 1927 by the death of the last remaining wild bison in the Caucasus. At that time, fewer than 55 individuals were held in captivity.
Fortunately, a group of dedicated conservationists was unwilling to let this enigmatic species be lost forever and started a breeding programme with just 12 individuals. These animals are the ancestors of all of the world’s existing European bison, and they, and every one of their descendants, has an entry in the European Bison Pedigree Book. Stored in Poland, it’s the world’s oldest record of the population of an endangered species.
The total population is now about 5,000, with 3,200 roaming free. However, the species is still listed as ‘vulnerable’ by the IUCN Red List, and efforts to ensure its survival are ongoing.
In 2003, Dutch water company PWN – which is involved in the management of a large part of Zuid-Kennemerland National Park – was asked to be involved in a pilot project involving the release of a group of bison in the park. A severe decline in the local rabbit population had led to the dune area becoming overgrown, and PWN was looking around for a natural way to combat the problem.
Using large herbivores to control vegetation in natural areas has been common in the Netherlands for more than 20 years, but no-one had yet used bison. PWN agreed to take part in the project, and opened up Kraansvlak – an area fenced off to the public – to the bison. ‘The philosophy was that bison, with their specific grazing behaviour, could be complementary to the Scottish Highland cattle, horses and sheep, which are already present in the national park,’ explains Piet Veel, who was managing PWN’s Department of Nature and Recreation at the time of the release.
In April 2007, following a long drive from Poland, the first bison were released. A year later, three more Polish bison were sniffing the Dutch sea breeze, bringing the herd to four females, one calf and a bull. Two years later, the first wild bison was born in the Netherlands, and today, the herd numbers over 20.
Although scientists now know a lot about the ecology of the European bison, there are still a number of holes in their understanding, and the herd has been the subject of numerous studies. The herd is monitored on a near-daily basis by a collection of PWN rangers, scientists and students, more than 40 of whom, from a number of different universities, have been involved in the project since its inception.
Most of the available data on the ecology of European bison has been collected from animals living in forested areas in Eastern Europe. While these animals have large areas in which to roam, they still have to be given supplementary food at certain times of the year. The Kraansvlak bison are doing fine without supplementary feeding, which provides researchers with a unique opportunity to study their food choices, particularly in winter, when food is less abundant.
Spanish student Esther Rodríguez began working on the project in 2010, carrying out a comparison of foraging behaviour and diet with Scottish Highland cattle and Konik horses. ‘I was very delighted to be given the opportunity to study these bison – until then, they were a mystical species to me,’ she says. ‘It was such an overwhelming moment to see them for the first time – these wild animals really take your breath away, especially when you see that they’re so relaxed around people.’
The studies have shown that more than 80 per cent of the bison’s diet consists of grasses, regardless of the time of year. This is supplemented with woody material from species such as European spindle, hawthorn and creeping willow. ‘During the first few years, the bison debarked spindle trees so enthusiastically that they created small cemeteries of it,’ says Rodríguez. ‘As a result, other vegetation got a chance to grow.’
‘As the spindle trees diminished, the bison switched to maple trees for debarking,’ says Ruud Maaskant, a PWN ranger. ‘It’s a pretty distinctive sight when the whole group has marked the trees with their teeth. For us, as managers of the terrain, it’s interesting to see. We don’t mind them eating from these trees. It just indicates that the maple is an alternative for them to the spindle tree.’
The researchers have placed GPS collars on a number of the animals in order to monitor their habitat use and determine which parts of the landscape they favour. The data suggest that they prefer to forage in rough grasslands and areas where shrubs are present. Deciduous forest is only preferred during so-called mast years, when acorns are abundant.
The bison tend to seek out sandy areas when it’s time to ruminate and rest. At such times they’ll often take a sand bath, which helps to open up the dunes and make them a more dynamic system, much to the delight of the park’s managers.
Because the area in which the bison roam is fenced off, opportunities for the public to view them is mostly restricted to an observation point near the lake. However, on hot summer days, the chance of seeing the herd from this spot is considerable, as they gather to drink and take sand baths.
Visitors keen to get a more intimate encounter can also join guided excursions led by PWN rangers. ‘People appreciate us telling them about the bison, the project and also about other inhabitants of the dune area that we manage,’ says Maaskant. ‘It’s very rewarding to come back from an excursion with people who are so thankful for our work.’
These safaris also give the researchers an opportunity to study the bison’s interaction with people. The results suggest that the bison are more relaxed in open areas and when people stay at least 50 metres away from them. They appear to be alert to people but have never shown any signs of aggression, which convinced the park officials to open a free-access walking route in 2012.
With several years worth of accumulated knowledge on bison behaviour and ecology, the project team now hopes that releases will take place elsewhere in the Netherlands. Thanks to its foraging behaviour and habitat use, the species has a very distinct impact on the landscape, making it more ecologically dynamic.
And given that part of the function of the national park is to provide recreational activities, the fact that park visitors have become so fond of these wild and impressive giants is an added bonus.