Woodpeckers sometimes excavate holes in house siding, especially softer wood or areas already weakened by insects. It’s not extremely common, but it is normal behavior, and high, quiet walls with an easy flight path are exactly the kind of spots they choose. At this time of year in Oklahoma, they’re not nesting – woodpeckers finish that by midsummer. A bird using a wall cavity now is almost certainly creating a winter roost, and any faint sounds you heard were likely the adult moving or calling inside, not young birds. You can close the hole, but only once the bird is out for the day (usually shortly after sunrise). After blocking it, add something the woodpecker can’t easily excavate again – metal flashing, hardware cloth, or another hard surface, and consider using visual deterrents like reflective tape. If you want to offer the bird an alternative, a roost box mounted on a quieter wall or tree nearby often works well. Woodpeckers are still protected, so you can exclude them from buildings, but you can’t trap or harm them.