The Carolina Wren have the same digestive track as all birds do, including the oesophagus, crop, liver, proventriculus, pancreas, gizzard, intestine, and the cloaca. The cloaca is the single way for the wren to excrete waste as opposed to mammals which have two excretory paths. Because of the Carolina Wrens high metabolism, they can eat up to 80% of their body weight a day.