His and Hers Field Marks

Nature is both stingy and generous with its field marks. And this dichtomoy is on full display in the back yard. On the one hand we have birds that I have found no obvious way to separate by sex, including Chickadees, Titmice, and Wrens---around here. And there are the slamdunk easy (for me: Bluebirds, Cardinals, Goldfinches, and House Finches). But Nature has also provided that caste of squint-and-verify, and this includes all of my woodpeckers. There are differentiating field marks alright, but one needs to look carefully. Take these Downy woodpeckers, photographed within two hours of each other. The male (on the left) can best be distinguished by that little patch of red on the back of his head. The female (on the right) has no red marker. The book says there are three other ways to tell them apart but even with photos I am not very good at those comparisons. Always with our woodpeckers it is necessary to look carefully for the right field marks. But this is good optical exercise for me. After all, I won't have BirdCam photos when I see birds in the wild!