Keese are blue bats with a wingspan of about 3 feet. They fly more or less randomly, lighting now and then on statues and floors. They will bite just about any creature they are able to.
Keese are a bit too large to fly very well, and don't have a great deal of stamina. When one is encountered, the Manager secretly rolls a 2 dice to determine how long the keese will stay in flight. At the end of the number of turns rolled, the keese will land and rest for 3 turns before taking off again, at which point, the Manager will again roll 2 dice.
Technically, keese aren't really bats at all, but larval vires.