One of the reasons people and animals share such a close relationship is that people have always learned important lessons from animals: what to eat, and what not to eat; when it is safe, or when there is danger about. Have you ever walked in a park or forest where there were no birds singing and no small animals to be seen? It's unsettling, isn't it? Where have the birds gone? And why did they leave? Often, animals can warn us of trouble before we are able to detect it for ourselves. Many people have been saved from fires by their pets, who, sensing the danger early, woke their owners and allowed them to get to safety. By carefully watching animals and their behavior, people can learn, and have learned, a great deal about their environment.