Contrast in Wing Bars
/Contrast is useful in many situations...let's try it on the "confusing fall warblers" (a term Tom and I really dislike): Pine, Blackpoll and Bay-breasted.
These birds actually have a number of separating points, but lets focus on wingbars for a moment. When we take these seemingly similar birds and put their wingbars side-by-side, suddenly we can see a fairly significant difference, specifically in the black between the wingbars:
Notice that in Pine Warbler, the wingbars are dusky white, and the space between them is grayish. In Blackpoll, the black between the wingbars is more contrasty, and in Bay-breasted it's a deep black contrasting white wingbars. So Pine is very easily separated with a good look, and in fact Bay-breasted is often separable by this mark...at the very least, when you see a fall Bay-breasted / Blackpoll type, this can be a tipoff that you have a Bay-breasted, and then take a look at other features like the finer eyeline, gray (vs. green) back, yellowish nape, and (often) hint of rusty wash in the flanks. Maybe those fall birds aren't quite as confusing as we thought...