That's a capybara, a giant South American rodent. They can grow as long as 1.3 metres and weigh up to 65 kilograms. They have teeth.
In conversation earlier, my wife informed me that there had been sightings of these creatures living wild in Britain. I was disturbed by this information; I really don't need another animal to fear while cycling.
There is no need to become hysterical. The solution came to me quite quickly. What we need is a large owl.