Bristle Feather Study
Bristle feathers are found on many species. Bristles are whisker-like feathers typically found around the mouth, eyelids and nares. Bristle feathers maybe unbranched or branched. The branched bristles can have minimum barbs at the base to more elaborate structures as found on nightjars. Some birds have both types of structures as shown in the various examples below. Bristles are sensitive to touch and vibrations. They assist in foraging and obstacle avoidance, protect from airborne particles, and sense airflow. Some sites state that bristles are used to funnel food. That was dispelled in an article about Willow Flycatcher bristles.1
1Conover, Michael R. and Miller, Don E. (1980) Rictal Bristle Function in Willow Flycatcher. The Condor, Vol. 82, No. 4, pp. 469-471
As part of a feather study, I documented the bristle feathers of each species with some interesting results.
Two great articles on bristle feathers:
ABTO, Melozone aberti
ACWO, Melanerpes formicivorus
AMCR, Corvus brachyrhynchos
AMKE, Falco sparverius
BANO, Tyto alba
Clockwise from top left, nare, manible, below the eye, above the eye
BUOW, Athene cunicularia
CACW, Campylorhynchus brunneicapillus
What look to be bristle feathers below the bill are actually modified contour feathers.
CHIC, Gallus gallus
Despite many websites that specialize in chicken related information, chickens do not have bristle feathers.
CHUK, Alectoris chukar
Chukars do not have bristle feathers
COHA, Accipiter cooperii
CBTH, Toxostoma curvirostre
FLOW, Psiloscops flammeolus
GRRO, Geococcyx californianus
A second review produced these results.
From the bill area.
From around the eye.
HASH, Parabuteo unicinctus
HOFI, Haemorhous mexicanus
Ostrich Bristle Feather
OSTR, Struthio camelus
Close-up of Ostrich bristle feathers. A close-up of the eye shows eyelash-like bristle feathers. Note the barbs.
Ostrich bristle feather
RTHA, Buteo jamaicensis
RNEP, Phasianus colchicus
A look at 300X magnification shows some type of growth reminiscent of a filoplume. The vane was not as delicate as a filoplume.