Already one of the largest urbanised areas in the world, the Pearl River Delta continues to urbanise at an alarming rate. When Zhao first arrived in Shunde, Guangzhou, he was worried because he could not see or hear any birds for the first hour. Where had all the birds gone? In recent years, birds have been used as indicators of possible changes in the environment. By looking closely at the types of birds and the number of birds, we can learn more about the current state of the environment.