Lena Chow sent in an image of the Spotted Dove (Streptopelia chinensis) showing short rictal bristles arising from the base of the bill (below). We are familiar with the long bristles in nightjars but unfamiliar with short bristles as seen in this dove.
Bristles are specialised contour feathers where the rachis lacks barbs. Such bristles projecting from the base of the bills in birds are known as rictal bristles. These bristles are believed to channel insects into the mouth but there is yet to be proofs of this. Wind tunnel experiments have demonstrated that these bristles protect the eyes from flying insects and other debris. Conover & Miller (1980) released particles in front of the mouths of Willow Flycatchers and birds whose bristles were removed had their eyes struck by these particles. On the other hand, George (2004) believes that these bristles may help birds detect movements of prey held in the bill, functioning like whiskers in some mammals.
Eyelashes of birds are another example of rictal bristles.
1. Conover, M. R. & D. E. Miller, 1980. Rictal bristle function in Willow Flycatcher. Condor 82: 469-471.
2. George, A. C., Jr., 2004. Form and function: The external bird.. Pp. 3.1-3.70 in: Podulka, S., R. W. Jr. Rohrbaugh & R. Bonney (eds.) Handbook of bird biology. Ithaca, NY: The Cornell Lab of Ornithology.