Golden Egg #51 is located on level 1-12 of Angry Birds Seasons South HAMerica. The Golden Egg is above the grassy arrow on the right side of the level. A high-flying Yellow bird is the best way to try to snipe the Egg, though it is very challenging. Keep flinging!
To obtain the star on the level, fling two Big Brother birds at the stone plank near the top of the level. The first should cause a chain disrupting the outermost pigs, and the second should handle the interior pigs. You have one more Big Brother if needed.