Can chickens smell fear?

Laura McAnea recalls her research investigating the olfactory capabilities of domestic hens, part of her MSc course at the University of Glasgow.

Last year I spent almost two months working with domestic hens as part of my MSc Animal Welfare Science, Ethics and Law research project at the University of Glasgow.

I wanted to investigate the olfactory capabilities of hens as we know they, like other avian species, have the physical features to enable a good sense of smell, but the exact function of this is still quite unknown [1,2]. My research assessed the role of olfaction in recognising potentially threatening or dangerous situations. I used a variety of odours to see if the hens could detect and differentiate between faecal samples from predator or non- predator species, familiar or unfamiliar hens, and stressed or unstressed hens. 

Investigating the olfactory capabilities of hens

The experimental apparatus consisted off a runway with a start box, an ‘odour zone’ and an end pen. The ‘odour zone’ was an enclosed space with plastic vinyl roof and doorways, and a mesh floor under which the odour was placed. I measured the times taken to reach the odour zone and hypothesised that the hens would take longer to approach, or completely avoid this when there was a predator odour or stressed hen odour. Additionally, I observed their behaviour throughout and hypothesised that they would show more alert or fearful behaviour in the presence of predator, unfamiliar and stressed hen odours. 

The hens were trained to exit the start box when the door was lifted, travel up a ramp and go through plastic curtains to enter and exit the odour zone, before making their way to the end pen where they could forage for a food reward. I trained them in stages, and in groups, so they that weren’t overwhelmed or stressed – but it didn’t take them long to work it all out!

The results provided some preliminary indication that hens can detect and differentiate between various odour cues. For example, hens displayed investigative behaviour in the presence of both novel heterospecific odours, but more fearful (freezing) behaviour in the presence of the predator odour.  This suggests that both scents were detectable and interesting to the hens, but that the predator cue was more threatening. Freezing behaviour was not observed in the presence any of the conspecific cues, so it could be suggested that the hens were neither threatened by their conspecifics, nor took any warning from their alarm scents. Although results of my study were not statistically significant they are helpful for improving the experimental design for futures studies in this area.  Furthermore, I had a lot of fun working with the lovely hens!

Intelligent, affectionate and wonderfully inquisitive animals

I had thirty sixteen-week-old Lohman-Brown female hens. I spoke to them all quite a bit and it wasn’t long before they were responding to their names. For example, I could go into the hen-house, call out their names and they would come to the front of their pens. One hen in particular was very responsive, as soon as I called her name she would jump off her perch and come bustling her way through the others to meet me!

They were all so curious and quick to investigate any new enrichment that was put in their pens, and they were extremely affectionate - some would follow me around for cuddles, or jump straight up to my hand. I would often go in and sit with them and they would hop right up on my knee or perch on my feet. They made a distinct noise when being stroked, similar to a cat’s purr. I also noticed different personalities within the groups -some were very confident and talked at the top of their voices whereas others were hung back and were more quiet.

Overall, my time with the hens made me appreciate them for being the intelligent, affectionate and wonderfully inquisitive creatures that they are!

Further Reading

[1] Caro, S. P., & Balthazart, J. (2010). Pheromones in birds: myth or reality? Journal of Comparative Physiology A, 196(10), 751-766.

[2] Jones, R. B., & Roper, T. J. (1997). Olfaction in the domestic fowl: a critical review. Physiology & behavior, 62(5), 1009-1018.


* This is a personal blog. Any views or opinions represented in this blog belong solely to the blog owner and do not necessarily represent the views or policies of World Animal Protection.