The northern flicker (Colaptes auratus) is a medium-sized bird of the woodpecker family. It is native to most of North America, parts of Central America, Cuba, and the Cayman Islands, and is one of the few woodpecker species that migrate. Over 100 common names for the northern flicker are known, including yellowhammer (not to be confused with the Eurasian yellowhammer), clape, gaffer woodpecker, harry-wicket, heigh-ho, wake-up, walk-up
Adults are brown with black bars on the back and wings. A mid- to large-sized northern flicker measures 28–36 cm (11–14 in) in length and 42–54 cm (17–21 in) in wingspan. The body mass can vary from 86 to 167 g (3.0 to 5.9 oz). Among standard scientific measurements, the wing bone measures 12.2–17.1 cm (4.8–6.7 in), the tail measures 7.5–11.5 cm (3.0–4.5 in), the bill measures 2.2–4.3 cm (0.87–1.69 in) and the tarsus measures 2.2–3.1 cm (0.87–1.22 in). The largest-bodied specimens are from the northern stretches of the species range, at the latitude of Alaska and Labrador, while the smallest specimens come from Grand Cayman Island. A necklace-like black patch occupies the upper breast, while the lower breast and belly are beige with black spots. Males can be identified by a black or red moustachial stripe at the base of the beak. The tail is dark on top, transitioning to a white rump which is conspicuous in flight. Subspecific plumage is variable.
This bird's call is a sustained laugh, ki ki ki ki, quite different from that of the pileated woodpecker. One may also hear a constant knocking as they often drum on trees or even metal objects to declare territory. Like most woodpeckers, northern flickers drum on objects as a form of communication and territory defense. In such cases, the object is to make as loud a noise as possible, so woodpeckers sometimes drum on metal objects.
Like many woodpeckers, its flight is undulating. The repeated cycle of a quick succession of flaps followed by a pause creates an effect comparable to a roller coaster.