High-speed displays encoding motor skill trigger elevated territorial aggression in downy woodpeckers

1) Many species perform social displays that incorporate complex body movements. However, the reason why such exaggerated behavioral signals evolve in the first place is unclear.
2) Recent work posits that physical displays arise in part because they showcase an animal’s motor skill—that is, the ability to produce challenging motor acts with great coordination, precision, and/or speed. Support for this idea is largely correlational, with few studies attempting to manipulate metrics of motor skill to assess their effect on physical display efficacy.
3) Here, we address this issue in the downy woodpecker (Dryobates pubescens). Individuals of this species compete for territories through the performance of drums, which are complex displays produced by rapidly hammering the bill against a resonate surface at rates of 16 hits sec-1. This display is a whole-body endeavor, and its production relies on the ability to swiftly oscillate the head forward and backward at fraction-of-a-second perio...