What causes bird peck in walnut trees?

• A. Woodpeckers pecking for insects.
• B. Insect-caused disease caused by sap.
• C. Wind damage.
• D. Yellow-bellied sapsuckers pecking holes to access sap.

Answer: (D)

Bird pecking in walnut trees is driven by a sap‑feeding behavior seen in a specific type of woodpecker. Yellow-bellied sapsuckers deliberately drill small, evenly spaced holes in the bark to access the tree’s sap. They create well-defined rows or patterns of holes, often around the trunk or major limbs, and return repeatedly to sip the sap as it oozes out. This is a distinct foraging strategy from other woodpeckers that mainly peck to find insects under bark or to hollow out cavities; their pecking isn’t focused on sap wells. Wind damage and the idea of a disease caused by sap aren’t how this pecking occurs—the activity is the bird’s intentional sap access, which is why this pattern is characteristic of yellow-bellied sapsuckers.