In 1984, Katy Payne visited the elephants at Washington Park Zoo in Portland, Oregon. She had been studying whale songs for the last fifteen years, and she was curious about the ways that elephants - the largest living land mammals - communicated with each other.

What Payne observed her first week seemed, at the time, to be little cause for scientific excitement. But on her flight home, she flashed back to a childhood experience of singing in the church choir. Suddenly she realized that she had felt in the presence of the elephants a deep throbbing in the air just like the lowest notes of the church organ. Payne and two colleagues were soon able to show that the elephants use powerful ultrasound - sound pitched too low for the human ear to hear - in communication.

This silent thunder allows elephants to interact over long distances. Payne and her colleagues went on to do important field research on elephant communication in Kenya, Namibia, and Zimbabwe. But in 1991 the peaceful rhythms of their work were violently interrupted by a cull - a planned killing - that destroyed five of the elephant families they were studying. This destruction convinced her that all life is sacred. Payne determined to challenge the philosophies that support culling.

Silent Thunder is a natural history rich in ponderings about the animal world and how humans participate in it. It is also a passionate story of Payne's own spiritual quest as she turns an observant eye on her own role in this world and honors the holistic perspective of her indigenous friends, who became her teachers in Zimbabwe.