[JAC: There was some discussion this morning about why so many mammals have light bellies. Greg answered in the comments, but I’d also direct you to this article on countershading (yes, it’s from Wikipedia, but it’s the best I could find). Greg happens to be our resident expert on animal coloration, and decided to add a short post based on a picture he saw in the local paper.]
by Greg Mayer
As the picture below shows, countershading doesn’t always work– sometimes the hawk does spot the chipmunk.
I saw this just today in my local paper. As was discussed in the comments on the latest set of readers’ wildlife photos, chipmunks being dark above and light below gives them a “flattened” aspect and makes them harder to see, but no protective coloration is perfect. There have been years when hawks nested in trees on my block quite close to my house, and mangled chipmunk remains would appear frequently below the nest. This year, I haven’t seen any hawks near the house, and chipmunks seem more common than usual.