Meeting Abstract

57.7  Sunday, Jan. 5 15:00  A moving background disrupts station holding in Anna’s hummingbirds GOLLER, B*; ALTSHULER, DL; Univ. of British Columbia, Vancouver, BC goller@zoology.ubc.ca

The movement of visual features across the retina, termed optic flow, is an important source of information for control of locomotor behavior in animals. For example, during forward flight the animal perceives self-induced optic flow as it moves relative to visual features in its environment. Insects have been shown to use optic flow to control velocity and altitude, measure distance, and navigate through cluttered environments. During station holding behavior, such as hovering flight in hummingbirds, self-motion optic flow is minimal and perceived optic flow could indicate a loss of positional stability. Do hummingbirds use background visual motion to stabilize their position during hovering? We addressed this question by tracking the head position of Anna’s hummingbirds (Calypte anna) in a free flight arena with three types of projected black and white patterns: spirals, vertical gratings, and horizontal gratings. When the projected patterns are steady, the birds maintain stable 3D position. Moving patterns cause the birds to translate along one of three axes: backward-forward, right-left or upward-downward, depending upon the background pattern motion. The response is not blunted by experience, as a looming spiral pattern continues to produce a response even after 40 repeated trials, though the properties of the response (oscillation frequency and amplitude) change significantly over time. In response to a background with both stationary and moving portions the hummingbirds increase their response with increased background motion. Our results suggest that hummingbirds use perceived motion relative to background features as an important cue to stabilize hovering.