The bill is slightly decurved and less chisel-like than that of a bark-drilling woodpecker, suited to digging into soil. Stomach-content studies have repeatedly found ants dominating the diet, sometimes in the thousands from a single bird, taken with a long barbed tongue that can extend well beyond the bill tip.
The yellow-shafted and red-shafted forms were once treated as separate species. They interbreed freely across a broad zone through the Great Plains, producing intermediates with orange shafts, and are now treated as one species with distinct subspecies groups. Where exactly the boundary sits, and why the hybrid zone has stayed narrow, remains an active question.
Flickers still excavate nest cavities in dead wood, and those holes are heavily reused by other species. In much of the range flickers face strong competition for cavities from introduced European starlings, which is one proposed contributor to the species' long-term gradual decline in North American surveys.