Daring players can Air Jump through the air towards one wall and Wall Jump up into one of the holes. Otherwise, wait for a Shaman to build a bridge to a hole.
Defeat the other Shaman and build a bridge. Simple and easy, but still watchout for some mice, as they can troll your bridge up and result in creating not more as super-long, tippy broken plank.
2 ways to complete Map 44. The one on the left is the simplest, the one on the right does not trap wall-jumpers.
This one is a BIT dangerous... Just place a plank with the "b" button in half in air, half on wood, then be on the wooden part.
Place an anvil or down ball on the air side and you will fly away!
(The higher the ball or anvil, the further you will fly)
Another possible idea is for the shaman to ghost spirit the mice across, but this often ends in more than half of the mice dying.