I spent most of my childhood surrounded by chickens.
We moved out of London when I was five to the rural countryside in the Cotswolds, an area situated in the middle of England that is full of rolling hills, green fields and small villages. Being city dwellers, we did not really know what to do with all the fields and foliage we suddenly had access to. So, being completely out of our depth, we were convinced to buy 30 (yes, 30!) Rhode Island Red chickens from a local farm.
We weren’t sure what we were doing, but we did our best to provide accommodations. We set up some nesting boxes and perches for roosting for these 30 chickens in an abandoned barn on the property. For the next 10 years of my childhood we continued slowly improving the chickens’ barn, feeders and general environment until we believed we were providing our chickens with the best life they could ask for.
One day, I came across an intriguing video discussing environmental enrichment for chickens. Environmental enrichment is the process of modifying the enclosure and sensory experiences of captive animals in order to improve their welfare [1]. I hoped to do the same for my own animals.
Gallus gallus domesticus, more commonly known as the domestic chicken, experiences the world primarily through its eyes. Humans have three types of cone cells that are sensitive to red, green and blue wavelengths of light, while chickens have four types of cone cells (i.e., they are tetrachromatic) sensitive to red, green, blue and violet wavelengths. This tetrachromacy means that chickens can see all the colors humans see as well as some UV-A light that is beyond the visible light spectrum of humans [2]. Thus, a lot of environmental enrichment for chickens consists of providing the right lighting for them. Domestic fowls need 6–8 hours per night of complete darkness so they can get a full night’s rest [3]. Whilst chicks enjoy resting in brightly lit environments, older chickens prefer to rest in dimly lit and shaded areas, saving the brightly lit areas of the pen for activities [3]. Very brightly lit environments have been shown to increase feather pecking and cannibalism; in addition, chickens can perceive the flickering of some lower frequency UV lightbulbs [3]. Therefore, one of the best things an owner can do for their chickens is provide natural lighting in lieu of artificial lighting with varying levels of light intensity across pens.
A chicken’s hearing differs from our own as well. At 60 decibels (normal conversation level), chickens can hear from a range of 9.1 Hz (lower than the lowest bass note audible to humans) all the way up to 7.2 kHz and are most sensitive to sounds at 2.6 kHz [1]. By comparison, the average human hearing range is tuned to much higher frequencies, between 20 Hz and 17kHz. Auditory enrichment for chickens is primarily focused around chicks where playing rhythmic recordings of maternal clucking to chicks has been shown to improve learning and memory and reduce stress in later life [1].
Smell and taste are underappreciated aspects of the domestic chicken’s sensory system as well. Chickens have been shown to recognize the smell of their home nest, predators, and familiar foods and are even speculated to recognize the smell of individual chickens in their flock [4]. Novel smelling foods are typically avoided by chickens and an owner may need to introduce a new food to chickens a couple times before they will take a peck [4]! Studies show that chickens display a strong preference for umami flavoured foods and are highly averse to bitter foods [6]. Thus, one could enrich the taste experience of chickens by giving them some worms or suet—both rich in umami flavour—and avoiding citrus foods like lemons or limes.
All animal species have innate behaviors and preferred habitats. Similarly, domestic chickens will be most happy in an environment where they can fulfill their most common innate behaviors which are perching, nesting, foraging, and dust bathing [1]. The best way to enrich the environment of your chickens is by providing an adequate outdoor space in a free-range pen with access to dusty areas, nesting boxes, soil/foliage with bugs/worms and raised perches to roost in. Environmental enrichments have also been shown to reduce the stress levels and strengthen the immune system of chickens [1].
Whether it was adding a football to the pen or trying some different feed, I have spent half of my life trying to provide the very best living environment for my chickens. And I hope this brief look into the inner workings of this domesticated bird’s sensory systems will help you to provide the best life for your chickens as well!
Written by: Felix Rawlinson is an undergraduate student studying molecular biology and neuroscience at Dartmouth College. He lives on a farm in the UK and loves to observe the behaviour of his cows, sheep, pigs, chickens and bees.
References
[1] Campbell, D. L. M., de Haas, E. N., & Lee, C. (2019). A review of environmental enrichment for laying hens during rearing in relation to their behavioral and physiological development. Poultry Science, 98(1), 9–28. https://doi.org/10.3382/ps/pey319.
[2] Kram, Y. A., Mantey, S., & Corbo, J. C. (2010). Avian cone photoreceptors tile the retina as five independent, self-organizing mosaics. PLoS ONE, 5(2), e8992. https://doi.org/10.1371/journal.pone.0008992.
[3] Prescott, N. B., Wathes, C. M., & Jarvis, J. (2003). Light, vision and the welfare of poultry. Animal Welfare, 12(2), 269–288. http://www.ingentaconnect.com/content/ufaw/aw/2003/00000012/00000002/art00009.
[4] Krause, E. T., Schrader, L., & Caspers, B. A. (2016). Olfaction in chicken (Gallus gallus): A neglected mode of social communication? Frontiers in Ecology and Evolution, 4. https://doi.org/10.3389/fevo.2016.00094.
[5] Liu, H.-X., Rajapaksha, P., Wang, Z., E Kramer, N., & J Marshall, B. (2018). An update on the sense of taste in chickens: A better developed system than previously appreciated. Journal of Nutrition & Food Sciences, 08(02). https://doi.org/10.4172/2155-9600.1000686.
Edited by Jacob Johnson and Jessica Schaefer
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