Information about self-motion and obstacles in the environment is encoded by optic flow, the movement of images on the eye. Decades of research have revealed that flying insects control speed, altitude, and trajectory by a simple strategy of maintaining or balancing the translational velocity of images on the eyes, known as pattern velocity. It has been proposed that birds may use a similar algorithm but this hypothesis has not been tested directly. We examined the influence of pattern velocity on avian flight by manipulating the motion of patterns on the walls of a tunnel traversed by Anna's hummingbirds. Contrary to prediction, we found that lateral course control is not based on regulating nasal-to-temporal pattern velocity. Instead, birds closely monitored feature height in the vertical axis, and steered away from taller features even in the absence of nasalto-temporal pattern velocity cues. For vertical course control, we observed that birds adjusted their flight altitude in response to upward motion of the horizontal plane, which simulates vertical descent. Collectively, our results suggest that birds avoid collisions using visual cues in the vertical axis. Specifically, we propose that birds monitor the vertical extent of features in the lateral visual field to assess distances to the side, and vertical pattern velocity to avoid collisions with the ground. These distinct strategies may derive from greater need to avoid collisions in birds, compared with small insects. The translational motion of images on the eye (hereafter referred to as "pattern velocity") provides a rich source of information about selfmotion and the surrounding environment and has been shown to play a prominent role in the visual guidance strategies of all flying animals studied to date (2-5). Honey bees use pattern velocity for a diverse set of flight controls: they balance pattern velocity on their left and right sides to navigate narrow passageways (6); they regulate pattern velocity to control their flight speed (7) and altitude (8); and they integrate pattern velocity to estimate distances to foraging sites, communicating this information to hivemates (9, 10). Pattern velocity thus represents an elegant solution to insect flight control that is robust to a range of spatial frequencies and contrasts (2, 3, 6, 7).In the first study to ask whether birds also use a similar strategy, Bhagavatula et al. (11) trained five budgerigars to fly repeatedly down a tunnel. The authors found that like bees (6), the budgerigars steered away from vertically oriented gratings that provided strong nasal-to-temporal (fore-aft) pattern velocity, and toward horizontally oriented gratings and blank walls that provided little to no nasal-to-temporal pattern velocity. However, because Bhagavatula et al. (11) used only stationary gratings and did not manipulate pattern velocity directly, the exact mechanism used by birds remains to be confirmed. More recent experiments demonstrate that pattern velocity does not affect the flight speed of budgerigars (12) ...

H istorically, non-Indigenous researchers carried out the majority of research in Indigenous (First Nations, Inuit and Métis Peoples) communities in Canada. 1 In this context, research rarely had direct benefits for the communities being studied and sometimes resulted in harms. 1-6 As a result, there is commonly a sense of apprehension and mistrust among Indigenous communities toward research by non-Indigenous researchers. 1 There are several Canadian policy documents with similar themes that guide research in Indigenous communities.