Eye marks in vertebrates: AIDS to vision.
Lines leading forward from the eye may function as aiming sights in many small vertebrates. The chief evidence is the correlation of distribution and positions of eye-lines in various vertebrate groups with predatory feeding habits. Dark patches around the eye may serve to reduce glare in species in bright environments. Facial patterns often have multiple functions.
Ficken
R W
RW
Matthiae
P E
PE
Horwich
R
R