The mice are machined from the top in one go, so the piece of wood is held down with screws, the squirrel is made with two sides then glued together so again just held with screws into the spoil board but the snail was machined on both sides so required a pair of dowels for location plus holding down, I tend not to use clamps unless there is no room for screws as I get a more positive hold down that way and less lightly to twist free or move while machining.

Hope that helps