Cat attacks are one of the most common causes of bat casualties.
Bats do have other natural predators (such as birds of prey) but cats, particularly, will learn the location of the bat roost and catch bats as they emerge.
If a bat has been caught by a cat it will almost certainly be injured. Even if you cannot see any obvious injuries there is a great risk of internal infection from the cat's saliva.
Any bats caught by cats will need the experienced help of a bat carer. Please follow this link for instructions on how to contain the bat and call the Bat Helpline 0845 1300 228.