Vision is the primary sense that birds use to perceive their environment and fly safely through it. Birds and mammals use very similar neural pathways for processing visual information. However, we know relatively little about what visual cues are extracted by birds and how these are used to orchestrate flight behavior. Research with insects has identified a number of vision-based algorithms to control specific features of flight, such as regulation of velocity and altitude, measuring distance, and homing. However, we do not know how visual algorithms interact to generate the complex flight trajectories observed in nature. Work in our lab has demonstrated that hummingbirds have very robust stabilization responses in free flight and we believe that they will be a very good model for understanding how birds transition between flight modes. The most effective way to study how these processes operate in flight is to track the motion of flying birds while directly manipulating their sensory environment. In collaboration with Mandyam Srinivasan (University of Queensland) and David Lentink (Stanford), we are developing new tools and experiments for studying the visual guidance of flight mode transitions in birds. This collaborative project is funded by a grant from the Human Frontier Science Program.