What chasing birds can teach us about predation risk effects: past insights and future directions

Abstract

Birds are the best-studied taxa with respect to our knowledge about predation risk assessment. In the past 4 years, global progress in this field has been made due to a remarkable number of synthetic reviews, meta-analyses, and comparative analyses that are based on databases containing tens of thousands of observations on how birds escape from predators. In addition, novel empirical studies, often on more than one species at a time, have provided new insights into mechanistic diversity. Birds fly, walk, and swim away from approaching threats and the distance at which they do so—quantified as flight initiation distance—reveals much about their perceptions of predation risk. The contexts that influence risk assessment and management in both ecological and evolutionary time have largely been identified by thorough study of the life history, natural history, physiology, environment, and phylogenies of birds. We have also discovered continental and latitudinal differences in risk management. A large set of applied studies now use this knowledge to both increase our understanding of the vulnerability of birds to anthropogenic disturbance, and provide insight into how best to manage it. Future advances require: (1) developing a better understanding of the sensory mechanisms involved in risk assessment, (2) studies of individuals that are sampled repeatedly, and (3) the development of decision-support tools for wildlife managers to help us better coexist with birds in an increasingly urban world.