Lateralization in feeding is food type specific and impacts feeding success in wild birds

Abstract

Current research suggests that hemispheric lateralization has significant fitness consequences. Foraging, as a basic survival function, is a perfect research model to test the fitness impact of lateralization. However, our understanding of lateralized feeding behavior is based predominantly on laboratory studies, while the evidence from wild animals in natural settings is limited. Here we studied visual lateralization in yellow-footed green pigeons (Treron phoenicoptera) feeding in the wild. We aimed to test whether different types of food objects requiring different searching strategies elicit different eye/hemisphere biases. When feeding on relatively large, uniformly colored food objects (mahua flowers) which can be present or absent in the viewed patch, the majority of pigeons relied mostly on the left eye-right hemisphere. In contrast, when feeding on smaller and more abundant food objects, with color cues signaling its ripeness (sacred figs), right-eye (left-hemisphere) preference prevailed. Our results demonstrate that oppositely directed visual biases previously found in different experimental tasks occur in natural feeding situations in the form of lateralized viewing strategies specific for different types of food. The results suggest that pigeons rely on the hemisphere providing more advantages for the consumption of the particular type of food objects, implying the relevance of brain lateralization as a plastic adaptation to ecological demands. We assessed the success of food discrimination and consumption to examine the link between lateralization and cognitive performance. The use of the preferred eye resulted in better discrimination of food items. Discrimination accuracy and feeding efficiency were significantly higher in lateralized individuals. The results showed that visual lateralization impacted pigeons' feeding success, implicating important fitness benefits associated with lateralization.

Keywords: Treron phoenicopterus; brain hemisphere dominance; feeding behavior; object discrimination; visual ecology.

FIGURE 1

Visual lateralization in feeding on different types of food items. (a) A yellow‐footed green pigeon is about to peck a mahua tree flower after inspecting a patch with the left eye. (b) When feeding on mahua flowers (left), the significant majority of lateralized individuals showed the preference to view the patch with the left eye (LE) prior to pecking. When feeding on sacred fig fruits (right), the majority of lateralized pigeons preferred to use the right eye (RE). *p < .05