Peanuts are a popular bird food, but they come with a genuine health catch that every owner should know about: the risk of a hidden mould that is extremely dangerous to birds.
The short answer
Birds can eat peanuts, but only fresh, plain, human-grade ones — and many keepers avoid them altogether. Peanuts are high in protein and fat, which birds enjoy, but they are prone to a mould that is deadly to birds, so quality and freshness matter more than with almost any other food.
The aflatoxin risk
Peanuts, especially raw or in-shell, are prone to Aspergillus mould, which produces aflatoxin — a toxin linked to fatal liver disease in birds — and the spores can also cause a serious lung infection called aspergillosis. You cannot always see or smell the mould, which is why cheap or bird-grade peanuts are risky. If you feed peanuts, buy fresh human-grade nuts, store them cool and dry, keep portions small and unsalted, and discard anything that looks or smells off.
Peanuts and wild birds
Peanuts are a staple of garden bird feeding, and many wild birds love them — but the same freshness rules apply, so buy from a reputable supplier. In spring, whole peanuts can be a choking hazard for chicks, so use a mesh peanut feeder (which only lets birds take small pieces) or offer crushed peanuts during the breeding season.