Behavioural Lateralization in Budgerigars Varies with the Task and the Individual

Ingo Schiffner,Mandyam V Srinivasan,Johan J Bolhuis

doi:10.1371/journal.pone.0082670

Abstract

Handedness/footedness and side biases are a well-known phenomenon in many animals, including humans. However, these so-called biases have mostly been studied at the population level - individual biases have received less attention, especially with regard to consistency over different tasks. Here we investigate behavioral lateralization in 12 male Budgerigars, Melopsittacus undulatus, a social parrot inhabiting the Australian bushlands. We performed 5 types of experiments to investigate lateralization, in tasks that involved climbing onto a perch, or landing on perches arranged in various configurations. The birds displayed highly significant, individually varying biases. The bias displayed by any particular individual varied with the task, in strength as well as polarity. Analysis of the data revealed that the preferred foot used for climbing did not coincide with the foot that was used while landing. Thus, landing choices are probably not determined by foot bias. Furthermore, these individual preferences were overridden completely when a bird had to perform a task simultaneously with another bird.

Highlights

Most work to date on “handedness” and behavioural and brain lateralization has shown that animals display consistent side biases
The underlying rationale is that unilateral handedness or footedness would direct a group of individuals of the same population to move or respond in the same direction, ensuring that all individuals stay with the group and do not become isolated and vulnerable, for example when being chased by a predator [13]
It is important to examine whether the biases that are displayed by individuals when they are tested singly, continue to persist when they are tested in the company of other individuals

Summary

Introduction

Most work to date on “handedness” and behavioural and brain lateralization has shown that animals display consistent side biases. Other studies that have found behavioural lateralization at the population level involve detection of either food or prey (cane toads: [2], domestic chick: [3]), or predators (domestic chicks: [1], fish: [4]) or social interactions with conspecifics (domestic chicks: [5], quails: [6]). The underlying rationale is that unilateral handedness or footedness would direct a group of individuals of the same population to move or respond in the same direction, ensuring that all individuals stay with the group and do not become isolated and vulnerable, for example when being chased by a predator [13] To test this notion, it is important to examine whether the biases that are displayed by individuals when they are tested singly, continue to persist when they are tested in the company of other individuals.

Methods

Results

Conclusion