# Lateralised Behavioural Responses of Chickens to a Threatening Human and a Novel Environment Indicate Fearful Emotions

## TL;DR

Chickens show fear-based behaviors using their left eye when exposed to a threatening human, suggesting they can interpret human demeanor.

## Contribution

This study demonstrates lateralized behavioral responses in chickens to human threat cues, indicating emotional interpretation.

## Key findings

- Chickens used their left eye more when viewing a threatening person, suggesting right brain hemisphere activation.
- Birds showed more nervous behaviors, like head changes and vocalizations, in the presence of a threatening human.
- Lateralized behavior was observed both in the test box and arena, confirming emotional responses to human demeanor.

## Abstract

It is hard to discern the emotional responses of an animal to a human being, but its behaviour is a key indicator. Chickens may detect a person’s demeanour and display fearful behaviour, including using their left eye, connected to their right brain hemisphere, which processes flight or fight reactions, more than their right eye to view the person. We compared the behaviour of chickens when confronted with a threatening person, who had their hands raised, reaching towards the bird with direct eye contact, with that of a neutral person, who sat with their hands on their knees and did not attempt to make eye contact. Birds viewing the threatening person used their left eye more to do this and had a more standing posture, compared with those viewing the neutral person. Birds also showed this lateralised behaviour more when first positioned in the test chamber. We concluded that chickens’ behavioural responses suggest that they are able to determine a person’s demeanour from subtle cues in their behaviour.

The demeanour of a human during an interaction with an animal may influence the animal’s emotional response. We investigated whether the emotional responses of laying hens to a threatening or neutral human and a novel environment were lateralised, from which their emotional state can be inferred. Twenty-five DeKalb white laying hens reared in furnished cages under environmentally controlled conditions were individually assessed for their responses to these stimuli. They were contained in a box before emerging into an arena with a threatening human, who attempted direct eye contact with the bird and had their hands raised towards it, or a neutral person, who had no eye contact and sat with their hands on their knees. When initially placed in the box adjacent to the test arena, birds that remained in the box used their left eye more than their right eye, and they showed evidence of nervousness, with many head changes, neck stretching, and vocalisation. Birds showed lateralised behaviour in both the box and arena. Birds entering the arena with the threatening person used their left eye (connected to the right brain hemisphere) more than their right eye, usually with their body less vertical, and were more likely to be standing than sitting, compared with those viewing the neutral person. This confirms the bird’s interpretation of the person as threatening, with left eye/right brain hemisphere processing of flight or fight situations. We conclude that lateralised responses of chickens suggest that a threatening person is viewed more fearfully than a neutral person. However, further investigation is required with a larger sample of birds to strengthen these findings and enhance the generalisability of behavioural responses.