There had been claims that bats roosted in the tree, but a survey concluded the tree was not a bat roost.

BBC: The tree in Irton

It's known that peregrines have roosted and hunted from the tower over the centuries until, in the mid-1900s, their numbers suddenly declined.

BBC: Derby Cathedral video proves peregrines hunt by night

Introduced to control the rats that had arrived with sailors, they had instead chosen to prey on the vast colonies of sea birds that roosted on the lava plains, wiping them out.

ECONOMIST: Ascension Island