After you go to the Burial Ground you should see a cage. You will also
see a sign that says DO NOT OPEN CAGE. The only way to get to Chicken
Island is to open the cage.  You should see a tree with one of those
monkeys in it. You should see one of those plants that give you melons.
Back up and throw a melon at the Monkey. If you are backed up far enough
the should throw the melon at the cage. Inside will be a rhino. Break
the fence in front of you and you are on your way.