A pellet, in ornithology, is the mass of undigested parts of a bird's food that some bird species occasionally regurgitate. The contents of a bird's pellet depend on its diet, but can include the exoskeletons of insects, indigestible plant matter, bones, fur, feathers, bills, claws, and teeth. In falconry, the pellet is called a casting.
Pellets from a long-eared owl.
Long-eared owl pellets and rodent bones obtained from dissected pellets (1 bar = 1 cm).
Pellet of a common kingfisher
Regurgitation (digestion)
Regurgitation is the expulsion of material from the pharynx, or esophagus, usually characterized by the presence of undigested food or blood.
Flesh fly, from the family Sarcophagidae "blowing a bubble". One explanation for this behaviour is that it concentrates the fly's meal by the process of evaporation. The diet of the flesh fly is very high in water content. The fly regurgitates the liquid portion of the food, holds it while evaporation reduces the water content and the fly then swallows a much more concentrated meal without the water content. This continues until sufficient amount of liquid is left for the fly. –
Moorhen chick being fed regurgitated food by an adult
Bubbling fly
Bubbling fly (Calliphora vicina)