Answer
Yellow-bellied sapsuckers created these holes. As described by the Cornell Lab’s All About Birds site, “Yellow-belled Sapsuckers perch upright on trees, leaning on their tails like other woodpeckers. They feed at sapwells—neat rows of shallow holes they drill in tree bark. They lap up the sugary sap along with any insects that may get caught there. Sapsuckers drum on trees and metal objects in a distinctive stuttering pattern.”
This week’s contest winner was Dick Hotchkin