Great grey owls are covered in thick grey feathers, which is very handy in the wild, as the grey colouring is fantastic camouflage.
It easily helps them blend into the background at night when they're hunting food. They have big round faces and bright yellow staring eyes. The disc shape of their faces also helps when hunting, as it directs sound straight to their ears.
This means they have acute hearing and can quickly detect rodents to eat and other small mammals, like rabbits and squirrels, even if prey is hiding under deep snow or in tunnels.
The amount of food available affects their breeding, so in a year when prey is scarce they might not breed. This means numbers regularly go up and down in the wild and, although they're not endangered as a species, careful monitoring is needed to ensure they don't reach the danger zone.
If you're ever lucky enough to see a Great grey owl in flight, with its large wingspan, you'll be stunned by its graceful beauty. Wild birds live in Scandinavia, North America, Canada and Mongolia.
Here, you'll find ours in special aviaries. We have a pair of them, who arrived from here in 2009 and they're the largest species of owl that we have in the zoo.