One of the less cryptically named defects in the wood products industry is caused by birds pecking into the cambium of a tree. Trees grow over these small wounds and a defect is formed. This can occur in any species of tree but can be more prominent in some.

The most common culprit is the yellow-bellied sapsucker. The medium sized woodpeckers drill holes in parallel lines or rings around a tree. They eat the sap and insects that are drawn to the sugary liquid. Males are black and white with red crowns and throats; females lack the red throat coloring. They get their name from the yellowish color on their underside. Hummingbirds also frequent sapsucker drill holes to drink the sap.

The defect can range from mild to severe depending on the population size and migratory path of these birds. If you walk in the woods of the eastern United State odds, are you can spot a ring around the trunk of a tree in the canopy. This is the proof of the presents of the yellow-bellied sapsucker. In extreme cases the ring can girdle the stem reducing the flow of sap up and down the tree. This can lead to limb die back and weak spots in the branches.

Bird peck will show up in lumber and is considered a defect, it looks like a small witch hat. According to the NHLA grading rules there are limitations on bird peck based on species. Some species are allowed more peck per unit than others.