Figure 1. Photograph of woodpecker (a) and human (b) skull. Photos (c, d) show the approximate difference in the orientation of brain. The orientation of the brain in the woodpecker's skull allows the force of impact to spread more widely, reducing overall impact on a specific brain region. In humans, the same sort of impact would be concentrated on a smaller region and have the potential to cause serious damage.
This figure is adapted with permission from Lorna J. Gibson (Journal of Zoology, 2006). Photographs by Jeremiah Trimble, Museum of Comparative Zoology, Harvard University, copyright President and Fellows of Harvard University.