Long Read: Bison Reintroduction in Kent, Final Project Report

Thanks to the support of Vp plc in May 2022, we were able to successfully introduce a herd of bison into West Blean and Thorndon Woods. These bison, the first of their kind in the UK for over 6,000 years, give us a unique opportunity to analyse the positive impacts herbivorous ecosystem engineers have on the landscape.

The past 12 months have been a period of learning for the trust and all the project partners,as we embed the bison into their new habitat, monitor their natural behaviours and the herd learns to navigate the dynamic of their new family.

In July 2022 we welcomed three female bison to the West Blean and Thorndon Woods, two younger females and our Matriarch. For welfare reasons, they were initially restricted to a small area of the woods, around 5 hectares. Soon our rangers began to suspect that one of the young females was pregnant, and in October they were proven right when our first calf was born!

The calf has thrived since its unexpected arrival, and is developing exactly as our Bison Rangers would hope to see. The herd have bonded well with the calf and we have witnessed the second female (or Auntie as we’ve colloquially named her) supporting both the mother and the calf. Often our Rangers have witnessed the Auntie teaching the young calf how to forage and navigate their surroundings.

In winter, we were able to open up a larger area of 50 hectares for the herd to explore, just in time for us to welcome the Bull. We faced some challenges during the Bulls arrival due to post-Brexit complications with his transportation. This meant that his release was delayed further than we would have liked, however we were pleased to see that this did not affect how he bonded with the rest of the herd.

The natural behaviours of the bull differ somewhat to those of the females, this is predominately because he will be encouraging them to mate. This give the herd the opportunity to expand, but also means that they will engage in the full range of behaviours you would expect in the wild. This is vital to the project, as we want to monitor how these behaviours impact the landscape. One of the key outcomes we are keen to understand is whether the herd starts to show a preference for certain areas for foraging, another for breeding, another for sleeping.

Learnings – The Bison

One of the key learnings over the course of the year has been that the bison appear to be able to self-medicate. Shortly after their release evidence of parasites were found in the dung of the matriarch. Our bison rangers then witnessed the matriarch eating bark from Yew trees, and later found that the parasitic load in her dung had reduced.

Similar activity has been observed when the bison charged through a mass of rhododendron, an invasive species, and emerged wearing a crown of leaves. It is thought that the animals were using the plant as an insect repellent in the heat of the summer.
These observations are vital to our understanding of the bison, how they navigate the landscape and how they use their environment to solve challenges they may face. Our Bison Rangers will monitor the animals for similar behaviours as the weather changes next year,to see whether we can evidence these practices.

As part of the monitoring and evidencing approach, the bison dung is being sampled. It is here that evidence of the parasites were found, and during the collections that Dung Beetle larvae were spotted. The Dung Beetle is of great significance to the ecosystem of West Blean and Thorndon Woods, and their return was a projected outcome of the project, however we were surprised that it occurred so quickly.

Learnings – The Landscape

Since the arrival of the herd we have seen trails start to open up through once dense scrub and woodland. This is a wonderful example of the ecosystem engineers replacing the need for human intervention. To achieve the same results manually, we would have needed to use heavy machinery to coppice areas of the woodland.

The benefit of this being achieved using natural resources is that the end result is a matrix of open trails, bramble, ruminated ground and dung. Together this offers new life a chance.Hard compounded soil will be dug over, giving new delicate shoots the opportunity to grow.These shoots will receive the sunlight they need to thrive thanks to felled trees, and the fertiliser and invertebrate presence crucial to their development due is available to the dung. Overall this means that the landscape will retain a much more natural ecosystem.

By eating invasive species, such as brambles, and opening up trails through dense silver birch thickets, they are allowing more light into the woodland, supporting a wide-range of other plants and animals to flourish in these spaces. Reptiles are basking in the bare ground created by the bison’s iconic dust bathing, and their dung is attracting a smorgasbord of insects, including dung beetles, for woodland birds to feast on, as well as providing fertile ground for an array of fungi.

The bison have been witnessed using tree bark to remove old fur, which also helps to encourage invertebrate life, and provides a vital resource for nesting birds.

Learnings – Monitoring and Evidence

A robust monitoring programme is essential to ensure we can demonstrate the positive impact that our ecosystem engineers are having on the woodland habitat, and therefore help to inspire and support future wilding and nature-based solutions projects across the UK and beyond.

Key updates from the monitoring programme:

  • Our third year of Wilder Blean survey work is now complete, and we are preparing toanalyse all the data recorded in 2023, before publishing a final report.
  • Winter tasks, such as our volunteer invertebrate identification sessions have been planned and are due to take place soon.
  • Over the last two winters, our wonderful invertebrate ID volunteers went through32,388 (2021 samples) and 27,650 (2022 samples) of insects collected at the Blean. This is helping us to build up an extensive picture of invertebrate populations and wider biodiversity within the woodland.
  • We have an exciting new collaboration with the Natural History Museum who are looking at soil eDNA for us, and we had the pleasure of giving a panel talk to their members earlier this year.
  • The peak count for Heath Fritillaries – one of the UK’s rarest butterflies – during 2022 surveys was 320 butterflies.

We will continue to learn from the Bison and other animals in the West Blean and Thorndon Woods through monitoring and evidencing the impact the animals have on their environment. Alongside this, the chance to work with these animals is teaching our Rangers new skills as they learn to spot patterns in their behaviour and signs of change in the animals. These vital skills will help to influence the work we do with other species across our reserves.

The Future

We are now looking ahead to the next exciting step in this project, where we aim to introduce innovative Bison Bridges that will connect areas of the woodland that would otherwise be fragmented by public rights of way.

The bridges will allow our ecosystem engineers to pass under footpaths,and free roam larger sections of the woodland, whilst ensuring that visitors can continue to access and enjoy all that the Blean woods have to offer. In total over 200 hectares will be made available to the bison using this method.

Defragmentation of the landscape is a crucial step. Through evidencing the impact the bison, and their fellow inhabitants have on a wider landscape, we will be able to share our knowledge with colleagues in the conservation sector and beyond, in the hopes to inspire others to take innovative steps to tackle the nature and climate crises.

Our hope is that defragmentation through connectivity will help us create a greener more prosperous future, and a Wilder Kent. To help achieve this we have launched the Bison Benefactor scheme. Funds donated by the benefactors will go towards the management of West Blean and Thorndon Woods, its inhabitants and the continual learning our unqiue ecosystem can provide.

Thank you to Vp plc taking action for nature and making the introduction of Bison to Kent possible.

Author: Kent Wildlife Trust


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