The shape of a bird’s bill or beak is closely related to the kind of food it eats and the way in which it collects or catches this food.
A crow or jay has a strong all-purpose bill, capable of killing small mammals but fine enough at the tip to pick up small insects. Many songbirds have slender bills for picking up insects from leaves or out of cracks; others have wide flat ones for catching flies or strong thick one for cracking seeds and nuts.
Birds which dig for worms usually have long bills with sensitive tips while many water birds have broad dredging bills. Divers and grebes have straight spear-like bills and the birds of prey have strong hooked bills for tearing flesh.
Birds which catch insects on the wing (nightjars, swallows etc.) have tiny beaks but an enormous “gape” by comparison.
Picture credit: google
