From dodging collisions to choosing your friends, behavior provides a means for animals to respond to diverse challenges. In my group, we study the dynamics of behavior with the goal of understanding how behaviors work and how they have evolved. In this talk, I will present two examples from our recent work on competitive and cooperative birds. The first study focuses on the evolution of agility in hummingbirds – a group of birds that uses flight to compete for food and mates. By examining the performance of flight maneuvers within and across species, and how this variation scales with muscle performance and morphology, we gain insight into how maneuverability evolves. In the second part of my talk, I will shift to a species of bird that is more cooperative than competitive, and a different kind of problem: how does an individual’s behavior change with the scale of the social network? This work focuses on wire-tailed manakins, a neotropical bird that (like us) cooperates to attain status. Although these two studies cover very different questions and approaches in biology, they both illustrate how patterns of scaling in behavior can help us understand the mechanisms that drive complex systems.