You can understand a lot about how an animal lives just by looking at its body parts. The size, shape, and position of a creature's limbs, for instance, give clues to how it moves. Animals that have long, powerful legs, similar to those of an antelope or a cheetah, are often very fast runners. Animals with large eyes generally see well in the dark and so are usually active at night.

Perhaps the best clues of all about an animal's habits come from its mouth -- not in the form of words, but in the size and shape of its teeth or beak. From this information it is possible to answer one of the most interesting and important questions of all: What does the animal eat? Just as humans use knives, forks, and spoons to cut or pick up food, so do many animals use their teeth or beak to handle their food. Often these mouthparts are as well-suited to a particular kind of food as any kitchen utensil.

Bird beaks can be particularly telling about a bird's way of life, suggesting not only the type of food eaten but also where and how the food is collected or captured. Some beaks, for example, are shaped like tweezers, perfect for grasping small objects with accuracy. The waxwing, jay, and flycatcher pictured in this collection of images have this type of beak. These birds eat small food items, delicately plucked from tree branches, from under bark, or straight out of the air. Indeed, flycatchers are named for their habit of catching insects on the wing, a feat that requires great precision.

Large food items require a different type of beak, and one of two handling strategies. The pelican pictured in this collection, for example, uses its very large beak and accompanying pouch of skin like a fishnet to catch fish that it ambushes from above. When it surfaces, the pelican swallows its catch whole. Hornbills, with their long, curved beaks, also swallow food whole. Their diet includes fruit, various species of invertebrates, and small mammals -- all of which go down in a single gulp. In contrast, falcons, which also eat large food items (some nearly as large as they are) but lack the pelican's gaping mouth, tear their prey into small pieces before swallowing.

Other foods and feeding habits require different types of beaks. The puffin has stiff bristles toward the back of its beak, which work like barbs on a fishhook and help the bird to hang on to five or more fish at a time. Hummingbird beaks look like long, skinny tubes. This shape allows these birds to access nectar deep within flowers. What kind of beaks do the birds in your area have? What foods do you think they eat?