An overgrowth of the skin or beak, most often seen in macaws, where the surface scales become thickened and flaky — usually a sign of nutritional deficiency or liver disease.
In macaws, hyperkeratosis often presents on the bare skin of the face: the smooth white skin around the eyes turns rough, scaly, and yellowish. In other species it can affect the beak (overgrowth, layering) or the feet (thick scaly patches).
The most common underlying cause is a vitamin A deficiency from a seed-heavy diet. It can also signal liver disease, especially in older birds or those fed high-fat foods. Treatment usually involves a diet shift to pellets and dark leafy greens, plus supportive vet care.
If you see it on a bird at point of sale, ask the seller about the bird's diet history and request a recent vet check. It's a treatable condition — but a sign that the bird hasn't had ideal nutrition.
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