Flickers are gorgeous birds and I always enjoy hearing the tap tap tap on a log or pole, then spotting the industrious bird. We had birch trees that had hundreds of pecker holes drilled in. I should have been concerned about the trees' health, but the holes are so interesting they make having birch trees worth it.
The careful rows amaze me. But what's even more amazing is how this matches the dark spots on the flicker's chest.