RIG/CAA: Effects of the Trade-off between Visual Acuity and Visual Fields on Anti-predator Behavior in Social Foraging Birds

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Organisms benefit from collecting information because it allows them to assess alternative environmental conditions (relative to food, predators, mates, etc.) before making decisions. One of the main gaps in evolutionary ecology is to understand how the configuration of visual systems influences the costs and benefits of information gathering. This is particularly interesting in visually oriented animals that live in groups, such as birds, because their visual environments are complex, as they can use two sources of information (personal and social) that can affect an individual's fitness (e.g., predator detection), and eventually social interactions (e.g., group size, neighbor distance). For instance, an animal can detect a predator through its own vigilance behavior (personal information) or through the anti-predator behavior of flock mates (social information). The goal of this project is to study how two key visual capacities (visual acuity and the extent of the visual fields) affect anti-predator behavioral responses in social foraging scenarios using four bird species as models: House Finch Carpodacus mexicanus, House Sparrow Passer domesticus, Brown-headed Cowbird Molothrus ater, and European Starling Sturnus vulgaris. The general hypothesis is that the degree to which visual social information is used to minimize vulnerability to predation will depend upon a trade-off between visual acuity and visual fields. Two predictions will be tested. First, species with relatively wide and less acute vision will exhibit less high-quality (head-up) scanning than species with relatively narrow and more acute vision due to greater visual coverage. Second, predator detection in species with relatively wide and less acute visual systems will be limited by the distance to the predator due to their reduced depth of vision; whereas in species with relatively narrow visual fields and more acute vision, predator detection will be limited by body posture and head-orientation due to their more constrained visual coverage. This study will enhance our understanding of the mechanisms involved in anti-predator behavior in species with different visual systems, which may have influenced the evolution of vision in passerine birds. New knowledge bringing together sensory biology and behavioral ecology will be produced and communicated to the scientific community through inter-disciplinary peer-reviewed journals and meetings, involving graduate and undergraduate students as coauthors, and to lay audiences through a non-technical publication. Research will be integrated with teaching through different activities with the general goal of heightening the interest of minorities in evolutionary biology. First, minority high school, undergraduate, and graduate students will be involved in the project. Second, new lecture and lab modules will be developed on the evolution of avian sensory systems. Third, outreach seminars will be given at high schools in communities with high representation of minorities to show the similarities and differences between human and avian vision and how these affect behavior. Fourth, a webpage will be developed emphasizing the relevance of inter-disciplinary research in sensory and behavioral ecology to understand the evolution of visual systems.