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Woodpeckers and the biomechanics of concussion

University of British Columbia

Woodpeckers are a remarkable clade of birds commonly known to use forceful blows of their beaks to drill holes in trees while foraging for boring insects or sap, and they also use their beaks to excavate nest cavities and loudly announce their territory by drumming. They regularly tolerate forces ten times greater than those that would give a human a concussion. Human concussions are the focus of a lot of attention and research efforts recently, especially in the world of sports and veteran's affairs where head injury's debilitating effects on immediate and long-term health are becoming more recognised. Woodpeckers are good organisms to study to gain insights into concussions. Many factors have been proposed to contribute to the woodpeckers’ ability to withstand the blows to its head. Some hypotheses are more likely than others, but the topic suffers from a lack of data. This thesis addresses the hypothesis that the brain is semi-isolated from the forces experienced by the rest of the head, and the hypothesis that woodpeckers have minimal space between their brains and skulls, and minimal cerebrospinal fluid. We used high-speed video analysis of wild captured Pileated Woodpeckers to evaluate whether there was any evidence that the brain case is semi-isolated from the rest of the woodpecker’s head. The acceleration profiles of points on the head and on the beak were not significantly different, and the distances between the head point and the beak point before and after a strike also were not significantly different. We used CT and MRI scans to visualize and measure the space between the brain and skull. The space was quantified and was not smaller than might be expected once scaling between a human’s head and a woodpecker’s head was taken into account. We conclude that woodpeckers’ resistance to head injury is not likely due to force deflection away from the brain, or especially tight packing of the brain, and hypothesize that it is due to scaling effects, a short impact duration, woodpeckers’ smooth brain, and possible neuroprotective mechanisms.

Text

2014-10-23

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/50869

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/