Wild hummingbirds rely on landmarks not geometry when learning an array of flowers
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Rats, birds or fish trained to find a reward in one corner of a small enclosure tend to learn the location of the reward using both nearby visual features and the geometric relationships of corners and walls. Because these studies are conducted under laboratory and thereby unnatural conditions, we sought to determine whether wild, free-living rufous hummingbirds (Selasphorus rufus) learning a single reward location within a rectangular array of flowers would similarly employ both nearby visual landmarks and the geometric relationships of the array. Once subjects had learned the location of the reward, we used test probes in which one or two experimental landmarks were moved or removed in order to reveal how the birds remembered the reward location. The hummingbirds showed no evidence that they used the geometry of the rectangular array of flowers to remember the reward. Rather, they used our experimental landmarks, and possibly nearby, natural landmarks, to orient and navigate to the reward. We believe this to be the first test of the use of rectangular geometry by wild animals, and we recommend further studies be conducted in ecologically relevant conditions in order to help determine how and when animals form complex geometric representations of their local environments.
KeywordsHummingbird Orientation Navigation Spatial memory Landmark Geometry
We thank Mark Hornsby, Ken Cheng and two anonymous reviewers for valuable discussion or helpful comments on the manuscript. Logistical support was provided by the University of Lethbridge and financial support by the Natural Sciences and Engineering Research Council of Canada (TAH, TAOF, DMZ) and the Association for the Study of Animal Behaviour (SDH).
Conflict of interest
None of the authors have conflicting financial relationships with any of the funding or approval agencies associated with the research reported here.
This research was conducted with the approval of the University of Lethbridge Animal Welfare Committee, meeting the standards of the Canadian Council on Animal Care, and under permits from the Canadian Wildlife Service and Alberta Sustainable Resource Development.
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