How to Tell If an Oak Tree Is Hollow

Visual Clues

• Dead branches, missing bark, fungal conks (mushrooms) on trunk.
• Cavities visible at base or old pruning wounds.
• Tree leans or has cracked major limbs.

Professional Assessment

Arborists use resistograph (micro-drill) or sonic tomography to map internal decay without damage. Drilling yourself risks spreading decay and weakening the tree.

Key Question

Was the fallen neighbor’s oak green and leafy? A living hollow oak is rare—usually hollows indicate dead or dying wood. If yours appears healthy, monitor annually; hire a certified arborist for peace of mind.