Blow up the wall and get 100 Red Pikmin. Get rid of all the Bolborbs and then grab some Blue Pikmin so they can push the box. Now launch the Red Pikmin onto the ledge near the lake. Go to the ramp the box was on and run away from the bird you find as you collect your Red Pikmin. Check where the star is located on your map and walk toward it. Another bird will show up. Kill it by throwing Pikmin onto its head repeatedly.