Why Don't Woodpeckers Get Concussions?

Description:  According to Lorna Gibsion of the MIT Department of Material Science and Engineering woodpeckers are able to avoid brain injury due to three factors "(1) their small size, which reduces the stress on the brain for a given acceleration; (2) the short duration of the impact, which increases the tolerable acceleration; and (3) the orientation of the brain within the skull."

Web Resource: Woodpecker Pecking: How Woodpeckers Avoid Brain Injury