Identify woodpeckers by using the same techniques you use to identify any other bird species, including taking note of the bird's physical appearance, range, habitat and vocalizations. Use a good field guide to birds in your area to identify woodpeckers.
Woodpeckers share several physical and behavioral characteristics, but they also differ in many ways. North American woodpeckers vary in size from the tiny downy woodpecker to the 16-inch-long pileated woodpecker. Though many woodpeckers have longer bills, very short bills distinguish the downy and hairy woodpeckers from the rest. Color markings are also key. The red-headed woodpecker has a completely red head, whereas the red-bellied woodpecker has red on the back of its head. The two sexes may also vary in markings.
Different species occupy different habitats. Many woodpeckers live in forests and open woodlands, but the gilded flicker also makes its home in the deserts of the Southwest. Some woodpeckers, such as the downy, live across most of the continental United States, whereas species such as the red-headed woodpecker only live in certain regions in the country. Vocalizations are a major species indicator and range from the rapid, high-pitched downward cheeping of the downy woodpecker to the lower, harsh and raspy calls of the red-headed woodpecker.