Hey I just learned something new! Much thanks to my bird expert friend Herma van Gerner for sharing this info: Apparently woodpeckers tend to peck for 3 different reasons with different soundbites/strokes, (1) for food, (2) for mating, (3) for marking their territories. If it's a fast rythmic sound (as was the case with my woodpecker), it's marking it's territory. Apparently it's not at all unusual for them to peck on brick walls. In fact they prefer pecking on strong objects that help amplify soundbites.