Q. Do bald eagles have the same digestive system as humans do?
Answer Contributed by Eagle Expert Peter Nye
A. Now there's an interesting question! The answer is, no. Birds in general have a higher metabolic rate than we do, which demands that they "process" their food as quickly as possible. This means getting it into a form from which they can extract the energy they need, quickly and efficiently. Birds, including eagles, have adaptations for doing this. Most importantly, part of their stomach has turned into a "gizzard", which we don't have, in which food is ground down to a fine consistency to permit rapid digestion. In eagles, this is also the place where "pellets" are formed. These are masses of material from prey that cannot be digested, such as fur, feathers, and occasionally bone, that then travel backwards from the gizzard up to the mouth and are cast (like vomited) out the mouth. Depending on what they have eaten, pellets are formed after the meal, overnight, and are usually cast out the next morning. Most fish are digested completely. Eagles have very strong stomach acids, and can digest bone quite well, which aids them in their own bone formation and in their egg-shell formation. Another major difference is that eagles (and other birds) have something called a "crop", in the upper alimentary track (esophagus) where food can be stored for days. This is extremely beneficial to eagles, who can store up to two pounds of food in their crop when prey is abundant, so they can then go without food for several days if need be. There are more differences, but these are two of the major ones.