Birding has a vocabulary all its own, from terms birders use to describe themselves (birder, birdwatcher, twitcher) to the types of birds we see (lifer, vagrant, rarity) to our gear (binns, field bag, guide). Some words are more unusual than others, and it’s an unusual one I want to explore – plumicorns.

What Is a Plumicorn?

Sometimes you discover a word you didn’t know was a word at all. “Plumicorns” sounds like a magical creature, a plum-colored unicorn or maybe a unicorn that eats only plums. But think about the defining characteristic of a unicorn – that single horn that is so instantly recognizable. “Uni” means one, “corn” is the horn, from the Latin “cornu” – the same origin as the more familiar term cornucopia.

“Plumicorn” then is actually a merging of the “corn” horn and the word plumage (from the Latin “pluma” for feather), a bird’s soft feathers. So therefore, a plumicorn is a feather horn.

What Plumicorns Aren’t

To be clear, a plumicorn isn’t actually a horn at all – it’s not solid or firm, it’s just an upright tuft of feathers, longer than the bird’s typical head feathers. Unlike the mythical unicorn that might use its horn as a weapon, a plumicorn cannot be used in such a way any more than a wing feather could be a sword, baseball bat, or dagger.

Furthermore, plumicorns aren’t ears, even though they’re frequently called ears in birds’ common names. These feather tufts have no practical application to a bird’s hearing in any way. While there is some speculation that plumicorns might serve a minor purpose in directing soundwaves to a bird’s ears for better audio detection, this is unlikely, given the positioning of plumicorns compared to the asymmetrical placement of a bird’s ears.

It should also be noted that a plumicorn isn’t a crest. A bird’s crest is a singular feature in the center of the bird’s head, while plumicorns are always in pairs and positioned closer to the sides of the head.

What Plumicorns Do

So what do plumicorns do? What is the advantage for a bird that has these prominent feather tufts?

Science isn’t quite clear on the overall purpose of these feathers, particularly since not all birds have them. They may serve some camouflage purpose, helping break up a resting bird’s silhouette or outline so it can better blend in to its surroundings, particularly the bark of a tree where the bird may be roosting. When raised, these unique ear tufts may make the bird appear more like a broken branch or a loose bit of bark, helping conceal it.

Because larger plumicorns can be moved and positioned quite distinctly, these feather tufts may also likely help indicate a bird’s moods and emotions, such as showing territoriality, aggression, protectiveness, fear, courtship behavior, or dominance when raised and alert. When smoothed out and lowered, the plumicorns may indicate submission, rest, relaxation, calmness, or ease.

Other possible functions for plumicorns may be to aid in individual species recognition by the size, shape, and placement of the tufts, or else to project a false sense of size to make the bird appear more intimidating to predators or competitors.

Ultimately, the full purpose of plumicorns is not well understood, and undoubtedly these feather tufts serve a wide range of purposes depending on each bird and its individual needs in any moment.

Who Has Plumicorns

These unique feather structures are most closely associated with owls, and in fact about 50-60 of the more than 225 owl species known in the world today sport recognizable plumicorns.

Several other birds do have their own plumicorns, however. The horned lark is one of the most obvious, as the birds wee bitty “horns” are the same type of structure horned owls display. Other non-owls that sport plumicorns, at least at certain times (such as during the breeding season – though there is much debate as to whether these may count as plumicorns), include the horned grebe, scarlet-horned manakin, great eared nightjar, tufted puffin, and the rockhopper penguin.

Have you ever heard of plumicorns? What do you think of these unique feather tufts? Share your thoughts in the comments!