Spatial association learning by rufous hummingbirds (Selasphorus rufus)

• Main Author: Wilhelmson, Christianne Elly
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/9145

Foraging theory provides a framework for understanding why animals make certain foraging decisions yet provides few insights into how these decisions are made. Psychological studies provide understanding of cognitive mechanisms but without the needed ecological context. This thesis continues the study of spatial association memory in rufous hummingbirds (Selasphorus rufus) in an attempt to understand its possible utility in the wild. In laboratory settings, rufous hummingbirds make associations between two spatially separate objects (a cue and a reward/response site) using spatial association memory. In Chapter Two, I investigated the ability of rufous hummingbirds to switch from using spatial memory to spatial association memory when visible cues remained reliable indicators of food location, even when the food location was changed repeatedly. Regardless of how often birds obtained food from the same location, they quickly used spatial association memory to relocate the reward when it was moved. Birds initially used spatial memory to locate the reward but once this failed they used the available light cue to learn the spatial association. Once birds were using spatial association memory, the spatial memory of the rewarding location was not reinforced in memory as they relied only on the association to locate the reward. In Chapter Three, I found evidence that the components of spatial association memory (the cue and the reward/response site) can be utilized separately from the association itself. Once birds learned a spatial association, a spatial memory of the currently and previously rewarding location remained in the absence of the light cue and this spatial memory was strengthened when birds fed repeatedly from the same location. This supports Brown (1992) who suggested that hummingbirds make spatial associations according to Gestalt theory, in which both the association and its parts are presumed to be perceived and remembered. I uncovered this information through analysis of intertrial activity, previously presumed to be independent of within trial behavior. Spatial association memory is more complex and flexible than expected and has characteristics to be useful in the wild, possibly to adjust quickly to profitability changes in flowers and patches.