The much-maligned cormorant is responsible for this surprising tactic. Cormorants, also known as water turkeys or grease chickens, roost on lakes across the country once the first cool front of the year arrives. It's common to find hundreds of roosting birds on lakes and reservoirs, where each can consume up to one pound of fresh fish in a single feeding. However, their digestive systems work poorly, so the fish they eat are only partially digested before they are expelled. The result is a catfish angler's dream.