Mike Beecher (Professor) and Çağlar Akçay (postdoc) describe the impact of personality variables (e.g. strong silent type vs signalers) on aggression and violent behaviors of song sparrows in Nature News and the UW News..

Here are those links: Nature News (http://www.nature.com/news/birds-might-bluff-about-intent-to-attack-1.14298 ) and the UW News (http://www.washington.edu/news/2013/12/03/signalers-vs-strong-silent-types-sparrows-exude-personalities-during-fights/).