Grey fantails sport a magnificent set of whiskers. They are the Jimmy Edwardses of the bird world. The facial bristles, which are pared back feathers, are divided into four groups set around the beak. Of these, the longest are those along the lower beak. At approximately 9 mm in length, they project beyond the beak’s tip. They are just visible in this photo.
Bristles serve several functions. In diurnal birds that hawk for prey, they are thought to protect the bird’s eyes from aggressive or wayward insects, present information about the position of prey caught by the beak and provide feedback on airflow around the head. This last function is useful in giving the bird an idea of its position in relation to flying prey.
You can see the bristles and get an idea of the restless behaviour of these little birds in this video from the Internet Bird Collection.
Reference
Cunningham, S.J., Alley, M.R. & Castro, I. (2011). Facial bristle feather histology and morphology in New Zealand birds: implications for function. Journal of Morphology 272: 118–128
