Updated: Feb 16, 2021
European Bison (Bison bonasus) are the largest surviving remnants of European megafauna. During the Pleistocene, bison could be found in vast herds roaming the forests and steppes from Central Russia to Spain. During this time, these herds would have resembled those of herbivores like wildebeest and zebra on the plains of the East Africa today. Bison were driven to extinction in Europe after World War I, as a result of poaching and habitat loss at the hands of man. It is thanks to extensive captive breeding programs and conservation efforts that bison numbers have been able to recover from a genetic bottleneck of 12 individuals which survived in captivity after the war.
Recent studies into European Bison genetics reveal an interesting picture of this species’ ancestry. Analysis from mitochondrial DNA has shown that the modern European Bison are the descendant of a hybrid ancestor: it is thought to be the offspring of a male Steppe Bison and a female Aurochs (the ancestor of modern cattle). These Aurochs genes may have been advantageous, allowing the European Bison to cope with changing ecological conditions as Europe warmed after the Ice Age period. Whilst the Steppe Bison was definitely known to have lived in the UK, it is not clear whether the modern European Bison ever lived here. However, given that the Steppe Bison is an extinct species, the European Bison is the most closely related living bison which would perform a very similar role in the ecosystem.
Bison are keystone species and ecosystem engineers; they have the ability to transform and manage landscapes to create a patchwork of forests and meadows as well as smaller microhabitats. Male bison can weigh up to 800 kilograms and can eat over 30 kgs of plant matter in a single day. These animals are mixed browsers/grazers and through their selective feeding behaviours, they are able to regulate plant biodiversity. Through the stripping of tree bark in the winter and rubbing against trees to scratch themselves, bison selectively kill trees which opens up the landscape. This allows smaller plants to grow, therefore boosting plant growth as well as carbon dioxide uptake. This helps restore a healthy mix of woodland and glades. The dead wood from the fallen trees can also support a variety of insect species which in turn are prey to birds, small mammals and bats. Bison also have sand baths where they roll in dust and sand to remove parasites as well as moulting fur. This creates microhabitats and clearings which generates a more structurally diverse forest. Another important role carried out by bison is their ability to disperse seeds, both through their digestive systems and the seeds which stick to their fur. This transports seeds across vast areas of forest. Bison footprints have also been shown to act as microhabitats: when they fill with water, they provide stopping points for amphibians like the yellow- bellied toad. This prevents amphibians from drying out as they migrate between pools of water. The ecosystem services provided by bison are extensive and this is why there are many advocates in favour of re-introducing them across their range.
The Wilder Blean Project is a collaborative initiative between the Kent Wildlife Trust and Wildwood Trust which aims to reintroduce bison to the UK for the first time in thousands of years. In the spring of 2022, a small herd of under 10 individuals will be released into Blean Woods. The bison will be kept in an enclosed area but they will be allowed to roam free; they will not be given any food or shelter as the aim is to keep them as wild as possible so that they manage the forest effectively. This project is the first of its kind in the UK, it is hoped that the bison will restore natural processes which will make the habitat stronger and more resilient in the face of climate change and biodiversity loss. Bison have already been reintroduced successfully to other parts of Europe; the UK lags behind when it comes to wildlife reintroductions. Maybe it’s time we start to make our UK landscapes ‘wilder’ and more resilient, by handing over the role of restoring degraded landscapes to those who can do it best: keystone species