Gil sprinted toward the tree and jumped to roll around with an arrow notched. He released it even before he could clearly see his target. With the feelings of the wind around him, he was able to tell the general area of the star fox along with his natural intuition. Both combined made him a much better hunter.
The arrow was nothing too complicated. He did not use a magical arrow and instead chose to use the wither spike arrow with the horned rabbit poison in it. This would cause the star fox to become paralyzed even if Gil did not finish it off with this arrow. Not that it was a problem, because when the arrow landed the star fox crumbled to the ground and the star like eyes just looked out empty.