The hercinia is a bird that is born in the Hercynian forest in Germany, from which it takes its name. It serves as a beacon for travelers because its feathers glow so brightly in the dark that they light up the path.

Despite the description saying the hercinia bird has glowing feathers, it is mostly drawn as a generic bird with ordinary dull feathers. In some illustrations the background or the bird itself is gold, or the bird is white, suggesting a glow. Some illustrations show the bird with a feathered head crest.