Behaviour 2019
Lateral position preference in feral horses
Sota Inoue1, Shinya Yamamoto2, Monamie Ringhofer2, Renata S. Mendonša3,4, Satoshi Hirata1. 1Wildlife Research Center, Kyoto university, Kyoto, Kyoto, Japan; 2Institute for Advanced Study, Kyoto University, Kyoto, Kyoto, Japan; 3Centre for Functional Ecology - Science for People & the Planet, Department of Life Sciences, University of Coimbra, Coimbra, Portugal, Portugal; 4Primates Research Institute, Kyoto University, Inuyama, Kyoto, Japan

Behavioural lateralisation is an effective way for animals to manage daily tasks by specializing behaviour to either side of the body. Many types of lateralisation are linked to the function of each brain hemisphere. Lateralisation of monitoring behaviour in mother-infant relationships occurs in a wide range of mammals, where infants frequently use their left eye to monitor their mother. However, few studies have focused on this type of spatial relationships among adults in daily life, such as during foraging. The present study focused on monitoring adult feral horse behaviour using quantitative analysis of spatial relationships, using drone technology. We found that horses form a localised spatial relationship to their nearest neighbour. Specifically, the nearest neighbour was located to the left rear of a target individual significantly more frequently than to the right rear. Furthermore, the nearest neighbour was less frequently located behind a target individual. We hypothesise that this relationship is caused by a left-eye preference, because the information via left eye is predominantly proceeded to the right hemisphere, which is dominant for social processing.