"Paul discusses just one of the many intersecting circles of life in the old growth forests. And thanks to noted ornithologist Dr. Steve Herman for confirming these markings are from the pileated woodpecker who stated "They sometimes work for years on something like this, returning daily or at least frequently to nonetheless place for beetle larvae and/or to beat in the excavation. They would have other similar site they would mine regularly."
For additional reading see:
Woodpeckers carry wood-eating fungi that may help them dig holes:
Kerry L. Farris, Martin J. Huss, and Steve Zack (2004) THE ROLE OF FORAGING WOODPECKERS IN THE DECOMPOSITION OF PONDEROSA PINE SNAGS. The Condor: February 2004, Vol. 106, No. 1, pp. 50-59.