They can be told apart by the shapes of their bodies, the color of their feathers and the places where they live. Let's take a look at each one of these and how to use a field guide. Bird Body Shapes Different birds have differently shaped bodies depending on what they do. If we look at a bird's beak, wings and feet, we can often tell what they eat and where they live. If we look at a duck we see that it has webbed feet and a flat beak.
Ducks use their webbed feet to swim and their flat beak to filter food from water.
We would know that it ate other animals. It could be a hawk, owl or eagle. It probably uses it to crack seeds. They eat insects. They spear their food or peck holes in trees.