[Closed] What's the best way to get rid of tree rats (squirrels) ?

The missus is doing her nut as the two resident tree rats are digging up anything and everything in the garden.

My auntie traps them in a cage and then drowns them in her pond.

Unfortunately, I don't have a pond and the missus would prefer a "humane" way of dispatching the fury vermin.

Any tips?