Rictal bristles are stiff, hair-like contour feathers that occur in rows projecting outward from the base of the bird’s bill, from each side of the corners of the mouth (rictus). Some species have similar feathers near the eyes as well that lie over the top of the bill as loral bristles (Ravens, for example).
They are believed to provide protection against insect legs and wings, thrashing prey, dust or other debris, particularly among birds that bore into wood while foraging. It is also possible, but not well studied, that they have a sensory function similar to whiskers.
These feathers are typically stronger and sturdier than the rest of a bird’s feathers, thus helping 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, especially visible in owls, hawks, eagles, woodpeckers, flycatchers, nightjars, and thrashers.
So the next time the conversation lags, why not bring up rictal bristles. I bet you will have everyone’s attention!
Sources: Wikipedia.org; birding.about.com; Cornell Lab of Ornithology; Sibley