SICB+ Through hawks’ eyes: reconstructing a bird’s visual field in flight to study gaze strategy and attention during perching and obstacle avoidance Minano, S*; Taylor, GK; University of Oxford; University of Oxford firstname.lastname@example.org http://www.biorxiv.org/content/10.1101/2021.06.16.446415v1
Diurnal birds of prey rely strongly on vision for executing flight manoeuvres. This is the case for Harris’ hawks (Parabuteo unicinctus), which hunt close to the ground and are therefore agile in avoiding obstacles. However, studies investigating the role of vision in bird flight typically involve simplified visual environments, in order to work with simplified visual inputs. Here, we present a method that allows us to obtain detailed information on the visual input likely available to the bird in flight, in more realistic flight scenarios. Our approach combines motion capture experiments, prior descriptions of the visual field of Harris' hawks, and tools from computer vision. This way we are able to synthesise detailed vision-based information, such as depth maps (distance measurements per pixel), optic flow data (motion patterns between consecutive frames), or semantic maps (which describe for each pixel the object it belongs to). Inputs such as these are often used in bio-inspired computer vision applications for navigation, and can provide novel insight into bird behaviour. We used these synthetic inputs to investigate visual attention and gaze-shifting patterns in over 200 trials from n=4 Harris' hawks executing perching and obstacle avoidance manoeuvres. Our aim is to test whether Harris' hawks use a strategy similar to that previously reported in humans and other birds, which consists of fixating on the centre of goals and on the edges of obstacles. A similar foveating strategy could be relevant to reduce onboard processing of visual data for navigation in autonomous unmanned air vehicles.