Drumming Woodpeckers

I always find that one of the first sounds of spring is the drumming of the greater spotted woodpecker. I heard my first one on Tuesday and then I heard them in every woodland. I wonder if it is the change in weather and light that stimulates them all to begin at the same time, or, is it that one male starts to establish a territory and so others have to respond. Whichever is the answer, it is a marvel that we can go from almost silence at midday to almost constant drumming in the space of just a couple of days.