(noun) A distinct ring of color encircling a bird's eye. The ring may be colored feathers that contrast with adjacent plumage, or it may be a circular patch of bare skin that stands out and highlights the eye. Eye rings may be full circles, partial arcs or broken rings, and may coincide with other markings such as brows, streaks or stripes on the face. Colored lores can combine with an eye ring to give a bird a "spectacled" appearance. If the eye ring is short and does not complete a circle around the eye, it is often called an eye arc rather than a full ring.
When looking at a bird's eye ring as an identifying mark, note the thickness, color and clarity of the ring. Some eye rings are blurry or faint, while others are sharply defined and strongly contrast surrounding facial markings. Compare changes in the ring relevant to the entire circumference of the eye; some eye rings may vary in thickness near the lores or other sections of the eye, particularly if there are other plumage changes.
Distinct eye rings can be found in all types of birds but are particularly noted among many songbirds such as thrushes and vireos.
Photo – Nashville Warbler © Dominic Sherony