Why all birds have pellets?

Not all birds have pellets. Only birds of prey, such as hawks, owls, and eagles, produce pellets. Pellets are formed when a bird of prey swallows its prey whole. The bird's stomach acids and enzymes break down the prey's flesh and bones, but they cannot digest the fur, feathers, or bones. These indigestible materials form a pellet, which the bird regurgitates and coughs up. Pellets are a valuable tool for scientists, as they can provide information about the bird's diet and hunting habits.