Cardinals and sparrows have heavy thick bills used to crack seeds. Meat-eaters, like the eagle, have a sharp, hooked bill to tear flesh. Robins and other birds with a varied diet have a bill shape that allows them to eat a variety of foods such as worms and fruit. The woodcock has a prehensile tip on its bill adapted for grasping. This allows it to probe the soil and grab earthworms.
Birds use their tongues for a variety of functions also.
Not only are tongues used to drink, but also to hold, pierce and tear food. Small stones and grit picked up with food remain in the gizzard grinding it for digestion. The gizzard is made of extremely strong muscles which in the wood duck can break down a whole acorn and in the canvasback duck grind fingernail clams for digestion. Birds have a high metabolic rate and, to survive, must eat large quantities of food frequently. Small birds eat large amounts of food in proportion to their size.