Try sparrows, they eat much less and peck those keyboards just as fast. Maybe you could bump your profit up to $3.1 million a month by switching over and reducing those bird feed costs!
or even better......wood peckers!! although they may break the mice. So you would need to take away the amount it would cost you to replace mice, from the extra amount you would earn, whiiiiiiich would work out about........ even.............................stick with the pigeons!