Echo was an African bush elephant matriarch who was studied for over 30 years by ethologist Cynthia Moss, beginning in 1973, and was the subject of several books and films. She was the first subject of the Amboseli Elephant Research Project, the longest-running study of a land mammal. The study of Echo and her family contributed significantly to the understanding of elephants, including their life-cycles, methods of communication, emotional lives, and cooperative care of the young. Echo died on May 3, 2009, at the age of 64.