Size is relative: use of relational concepts by wild hummingbirds

Abstract

Rufous hummingbirds ( Selasphorus rufus ) will readily learn the location and the colour of rewarded flowers within their territory. But if these birds could apply a relational concept such as ‘the larger flowers have more nectar’, they could forego learning the locations of hundreds of individual flowers. Here, we investigated whether wild male territorial rufous hummingbirds might use ‘larger than’ and ‘smaller than’ relational rules and apply them to flowers of different sizes. Subjects were trained to feed consistently from one of two flowers. Although the flowers differed only in size, the reward was always contained in the same-size flower. The birds were then tested on a choice of two empty flowers: one of the familiar size and the other a novel size. Hummingbirds applied relational rules by choosing the flower that was of the correct relational size rather than visiting the flower of the size rewarded during training. The choices made by the hummingbirds were not consistent with alternative mechanisms such as peak shift or associative learning. We suggest that while hummingbirds are very good at remembering the spatial locations of rewarding flowers, they would be able to use relative rules when foraging in new and changing environments.

Reward history modulates attention based on feature relationship.

“…We provide evidence for value-driven relational attention, which might be well suited for rapid stimulus prioritization under noisy conditions, especially in perceptually demanding situations where multiple objects appear simultaneously and are perceptually similar. A recent study showed that animals applied relational rules when foraging, choosing flowers that matched the relative size, rather than the absolute size of a previously rewarded flower (Brown et al, 2022). These findings indicate the prevalent use of relational information across species that could be advantageous for living in dynamic and complex environments.…”