Eavesdropping iguanas make use of their noisy neighbors...

This blog post details a recently published scientific study which showed that Galapagos iguanas make use of the alarm calls of mockingbirds.  The iguanas are susceptible to predation by large hawks, and often do not see them until it's too late.  However, they significantly improve their chances of survival by listening and reacting to the warning calls of mockingbirds nearby.