Tap to watch a video report by ITV News Meridian's Tony Green.
A bison rewilding project in Kent has received the appreciation of one of Hollywood's biggest stars.
Leonardo DiCaprio, who is also known for his work as an environmental campaigner, has shared the work being done in East Kent with his 19 million followers on Facebook.
On Facebook, DiCaprio said: "European bison are the continent’s largest land animal and were extinct in the wild a century ago.
"They are recovering through reintroduction projects across Europe, and recently three were released into the Kent countryside in Canterbury, becoming the first wild bison to roam in Britain for thousands of years.
"The Wilder Blean project’s mission is let the animals’ natural behaviour to nourish the commercial pine forest into natural woodland, allowing for new plants, insects, and wildlife to thrive in this habitat."
Last month, bison were released into the wild by conservationists to help tackle the nature and climate crises.
The release, led by Kent Wildlife Trust and the Wildwood Trust, forms part of a £1.12 million project to manage West Blean and Thornden Woods near Canterbury, Kent, funded by the People’s Postcode Lottery Dream Fund.
ITV Meridian's John Ryall saw the bison being introduced to the Kent woodland
However, there are fears these breeding programmes designed to save critically endangered species could now be jeopardised by Brexit.
Zoos in Kent say they are being prevented from transferring animals because of red tape.
While three female bison are already in Kent, the bull hasn't arrived yet due to paperwork delays.
Judi Dunn from the Wildwood Trust said: "For this year, for this particular bull, we've started in April, and I still don't have a date that I can give our managers as to when this bull is going to be coming into the country."
She added that actual health certificate that an animal needs to come into the country has changed significantly and there's a quarantine requirements that all adds to the length of time that the animal is being prepared really for movement.
Joe Judge from the British and Irish Association of Zoos and Aquariums said: "When we were in the EU, there used to be very simple paperwork and you could transfer animals quite easily, but now that we're not in the EU blog, we have to have different paperwork for each individual EU country."
A Defra spokesperson said: "This shows the real harm the bureaucratic approach the EU has chosen to take on animal and plant health. We’re ready to continue to negotiate on this where sensible pragmatic compromises can lead to improvements for everyone.
“Meanwhile we are working closely with the Animal and Plant Health Agency and the British and Irish Association of Zoos and Aquariums to identify priority exports where there are welfare concerns or implications to breeding programs.
“All of the requests for export health certificates for exports of zoo animals have been successfully fast tracked.”