On an autumn evening in Guilin, China, two fishermen and their trained cormorants rest on their rafts. Cormorant fishing is a Chinese tradition that goes back more than 1,000 years. The fishermen tie small snares around the cormorants' necks. The bird leaves its post, catches a fish in its beak but can't swallow it, and then returns to the boat, where the fisherman retrieves the catch.