I often have a similar issue … in my home office.
M-Cat and Fluffy, who looks as though he ought be holding a 40 and yelling for someone to make him a sandwich. M likes the Stranglers while he sits in his bowl, and Fluffy only listens to songs nobody else likes.
What is it about cats and keyboards? (I had the same problem when worked at home - my cat developed some of my best work!)
A mouse is too small to sit on and is better looked at from the most convenient location while disabling the primary user from using the machine…hence the keyboard.
Try a parrot with a penchant for prizing keys off the keyboard
Probably explains my spelling