You can't do much as a mouse; wait for the shaman to do something.
The safest way of solving this map is to build a construction of anchored planks from the first platform to the other. Attention: This way is only safe if the construction is well-stabilized by red anchored planks - that's why this solution is not recommended for Hard Mode Shamans.
Another way is using cannonballs: Don't place them exactly next to the mice, but a little under their feet too. This will make the mice fly up a bit, so they dont need to walljump the other platform. If the cannon isn't placed well, all the mice - including the shaman - are mostly killed.