I am planning on creating an African Savanna habitat that will be home to elephants, giraffes, zebras and ostriches. Do I need one large shelter building for all of them or, if I create one for each, will they use the one meant for them? Is there a way to dictate which shelter they use. For example, I can build a tall shelter with a tall door for the giraffes but what keeps the zebras out? Conversely, I can build a low shelter with a short door big enough for the zebras and then the giraffes and elephants couldn't get in but what would keep the ostriches out?