(noun) A distinct field mark on a bird's wing caused by contrasting colors on the tips of the primary and secondary coverts. Whether the wing is folded at rest or extended in flight, these contrasting tips form a distinct stripe of color across the wing. The color of the bar may be light or dark, though light bars are more common, and the shape, width and length of the wing bars will vary depending on the species. These are especially common field marks among sparrows, warblers, finches and other small birds.
Wing bars are common field marks and are often some of the easiest marks to see for proper bird identification. To identify birds with wing bars, note the color of the bar, how far it extends across the wing, how thick it is, whether or not it is straight or somewhat spotted and how many bars are on the wing.
Photo – Townsend's Warbler © Tim