(noun) Narrow, stiff, hair-like feathers at the base of a bird's bill. These feathers point out from the bird's face, and some species have similar feathers near the eyes as well. While the purpose of rictal bristles is not well studied, they are believed to help provide protection against insects, dust or other debris, particularly among birds that bore into wood while foraging. It is also possible that rictal bristles have a sensory function similar to whiskers. These feathers are typically stronger and sturdier than the rest of a bird's plumage, which helps them resist wear from contact with different surfaces.
Not all birds have rictal bristles, but they have been noted in a wide variety of bird families, with extensive appearances among woodpeckers, flycatchers and thrashers.
To use rictal bristles for bird identification, note the position, length and quantity of these specialized feathers, and compare those observations to the bird's behavior while foraging.
Photo – Downy Woodpecker © Matt MacGillivray