Chickens are smarter than most people realize

A review of the research paper "Thinking Chickens"

There’s a clip of the famous director Werner Herzog talking about chickens that went viral a few years ago. In it, Herzog claims that “The enormity of their stupidity is just overwhelming.”

Looking at how we treat chickens in the modern world, it’s safe to assume that most people agree with him.

I went looking for the best book I could find on chicken intelligence that would push back on that belief. The kind of book that would make even the great Herzog sit up and pay attention.

While there are a lot of popular history books that trace the chicken’s rise to prominence, I found nothing that was like, “18th century history and anecdotes aside, here’s what we know about the mind and behavior of the world’s most ubiquitous bird.”¹

Thankfully, I discovered the work of Dr. Lori Marino, a researcher who wrote exactly what I was looking for back in 2017. It took me a little extra searching to find her chicken magnum opus, because it’s not actually a book. It’s a 21-page research paper called, “Thinking chickens: a review of cognition, emotion, and behavior in the domestic chicken”.

Who needs a long book that wastes time on apocryphal stories about what Socrates might have said about a chicken when there’s a wonderful research paper that cites 216 sources sitting online for free?

While Marino declares no conflicts of interest, it’s undeniable that she has an agenda. She clearly thinks chickens are intelligent and emotionally complex creatures who deserve better treatment. That said, the research paper is not a polemic. It’s a thorough exploration of all the peer-reviewed data she could find. She clearly states her intentions in the abstract:

I examine the peer reviewed scientific data on the leading edge of cognition, emotions, personality, and sociality in chickens, exploring such areas as self-awareness, cognitive bias, social learning and self-control, and comparing their abilities in these areas with other birds and other vertebrates, particularly mammals.

She starts out with the caveat that lots of research on chickens is kind of garbage. People don’t seem to care about learning the true breadth of their abilities, only how to make them easier to manage as a food source. Chickens are often studied under unnatural and weird conditions that don’t actually tell us much about their cognition as a whole.

Studies that try to showcase how smart a bird is tend to focus on crows and parrots. What might we find if we put chickens in the same situations? It’s hard to say. Still, there’s a lot we can learn from the research we do have.

Numerical Abilities

Chickens, if given enough training, can do fairly advanced calculus. Kidding. We have not learned how to go full Flowers for Algernon with them yet. But they really can do some cool stuff with numbers.

Scientists have done a surprising amount of studies on chicks between two and five days old to learn about their numerical abilities. We now know that chicks can count, add, subtract, and “map numbers onto geometric space”. The geometric space thing was proven by the fact that they always associate smaller quantities with the left and larger on the right. All these traits are shared with known to be smart creatures like Rhesus monkeys and humans.

Can we step back for a second and appreciate how young these little birds are? Two days ago they were in a freaking egg, now they are counting? Seems like a pretty impressive little brain if you ask me.

Picture by Andrey Rudakov/Bloomberg via Getty Images (source)

Interestingly, all the studies we have looking at numerical ability are on baby chickens. We don’t know much about how adult chickens do with counting, a fact which bothers Marino.

There is a paucity of information about how these abilities play out developmentally into adulthood in chickens, and more information is urgently needed about this process to gain better insight into what these capacities mean for cognitive complexity in a comparative context.

I love the use of “urgently” in that quote. I can feel Marino looking out at us all, shaking her head in dismay. “Another million chickens just got killed in the time you spent subtly manipulating the color and size of the contact sales button on your app,” she’s saying. “Where are your priorities?! Let’s get adult chickens to do math!”

I’m totally with her. It’s still a funny thing to push for.

Time perception

How birds perceive time has long been of interest to me. What if birds experience time really slowly, making all the agony we put them through worse than it already is? Sadly, this doesn’t come up in the section on time perception.²

What Thinking Chickens does give us is quite a bit of fascinating discussion about memory, planning, and self control.

Chickens have the ability to perceive the passage of time. I figured this would just be self evident, but we humans have to prove everything I guess. In this case, there was a study where chickens heard different sounds and then either had a positive (food), neutral (nothing), or bad (squirted by squirt gun) outcome. They were tested to see if they had a “differential emotional response.” That seems to mean, “Did they get upset if they heard a sound that meant they were about to get blasted by a grad student with a super soaker?” Yes, they did. Now, thank god, we definitively know that chickens can “anticipate a future outcome.”

It gets a lot worse for research chickens than getting hit by super soakers, such as how we test their vitals while roasting them to death (Screenshot: The Intercept / North Carolina State University footage that Animal Outlook obtained via FOIA (source)

Chickens do as well as primates on certain tests of episodic memory, such as with experiments that test how long they can remember the trajectory of a ball that was set in motion and then hidden. They can do it for 3 minutes if you’re curious, which I firmly believe is longer than many human children I’ve been around.

Speaking of ways they can do as well or better than human kids on tests, they can show self restraint. They showcase this ability by doing a kind of chicken marshmallow test, where they learn to wait for longer periods of time in order to get a larger food reward. And, I presume, by how they don’t peck out the eyes of a researcher shooting them with a squirt gun.

Emotion

Chickens feel the full gamut of emotions. This is a fact that, given how most chickens live, you wish wasn’t true. Here’s Marino on how they can feel fear:

[chickens experience] tonic immobility upon restraint, and avoidance in some cases of the appearance of novel objects. Emotional responses in chickens are accompanied by physiological reactions, i.e., tachycardia and bodily fever (also known as ‘‘emotional fever’’), which underscore the shared characteristics of these emotions in chickens with other animals and humans.

Also, remember the Very Important Study where they used squirt guns to prove chickens can perceive the passage of time? It was noted that, while waiting to be squirted, they showed anxiety by pacing a lot and moving their heads around. When they were waiting for the positive reward they did none of that — they preened and ruffled and performed other relaxation behaviors.

Chickens, like all animals, want to feel good. They want to be happy. In another example for the ‘you can’t believe they have to prove this stuff’ files, researchers have shown that, “Chickens consistently choose to be in environments which offer better welfare as measured by several physiological welfare indicators.” Who would have thought?!

A final cruel but fascinating study to consider—researchers separated mother hens from their babies, but allowed the hens to view the chicks. They attached all sorts of measuring devices to the hens. They then applied aversive puffs of air to either the moms, the babies, or harmlessly outside of either cage. When the air puff hit the moms or missed altogether, they had no response. But when the air hit the babies, the moms got frustrated and worried.

There was a demonstrable response on the part of the mother hens, with physiological and behavioral changes indicating emotional distress. Their responses included increased heart rate and lower eye and comb temperatures (indicating vasoconstriction and increased body core temperature) as well as standing alert and maternal clucking. The hens’ responses were clearly reserved for when their chicks were experiencing the air puff, rather than a generalized negative response […] A later study showed that the hens’ responses were not simply due to increased vocalization on the part of the chicks. The hens were responding to what they knew about the aversive nature of the air puff and the fact that it was being applied to their chicks.

This shows they feel empathy.³ If more of us could experience the same for them, that would be nice.

Communication

Chickens are no dolphins or anything, but they have a respectable repertoire of 24 different vocalizations. They use those 24 noises to the fullest, engaging one another in complex forms of communication. To cite just one area of research, it’s been shown that they have meaning-laden alarm calls for different situations. A chicken makes a different noise for a land-based predator versus a flying predator. And both of those vocalizations are separate from “there’s a ginormous hawk flying at us super fast, code red!!” They can even disguise where they are while doing an alarm call, which I thought was neat.

Here’s a fun video showcasing different chicken vocalizations.

Marino puts their overall communication abilities on par with primates. That feels like a stretch to me but hey, she’s the neuroscientist. I’m never going to fault anyone for hyping up the chicken.

Visual Cognition

Chickens have been shown to have up to stage 4 object permanence. I’m still not 100% sure what that means, but there are only 6 stages, so it must be pretty good!

What I grasped is that chickens can hold images in their minds representing things that are no longer in their visual field. This alone should give some credence to the idea that they are perceiving the world in a sophisticated manner.

Whether chickens can be friends with giant, goofy almonds has still yet to be researched (source)

Studies show that chicks as young as 2 days old can already do quite a bit of object permanence-ing.

Reasoning and logical inference

It takes a typical human 7 years to be able to perform a type of deductive reasoning called transitive inference. This refers to one’s ability to figure out a relationship between things even when they haven’t encountered all the components yet. Along with 7-year-old and up humans, chimps, other monkeys, rats, and some birds can all do this.

It was proved that chickens can do it as well. Someone did a clever, if somewhat intense, study where birds would observe other birds fighting, as they naturally do to figure out a pecking order.

Let’s say chicken A loses a fight with chicken B. Then, chicken A watches chicken B lose a fight to chicken C, who they’ve never met before. If chicken A then encounters chicken C, chicken A doesn’t bother fighting. As a favorite Simpsons line of mine goes, it “folds like Superman on laundry day.” This implies that “sophisticated logical reasoning may underlie what is perceived to be a rather simple behavior—the pecking order.”

Self Awareness

While I am content to back off from eating something that can count and visualize and plan and feel emotions, some people won’t be satisfied unless we can prove there is some sense of “I” in the mind of a chicken. Do they know they exist? Are they mad about all the chicken nuggets? Do they internally cringe at every ‘why did the chicken cross the road’ joke?

The answer is we just don’t know. No one has rigorously tested self awareness in chickens. Marino points to it as “an excellent option for further study.”

What the paper does say is that the previously discussed abilities of self control and logical inference hint that there could be self awareness. Marino seems especially intrigued by the self control piece, pointing out that, “The presence of self control over time in chickens may indicate a cognitive capacity on a continuum of complexity with foreplanning and mental time travel.”

I think it’s important to keep in mind in these cases that we still have no way of definitely proving another human is conscious, either.

Social Cognition

Chicken intelligence truly shines through when we look at how they behave in natural social settings. This is the kind of stuff it might be hard to notice in the brutal and restrictive confines of a factory farm, which is partly why people are not walking around talking about how brilliant chickens are. (That, and people like the cursed Werner Herzog.)

Studies show that chickens can learn from watching each other, keep track of social hierarchies, and recognize many different other chickens, both live and via slides. I like to imagine they’d enjoy FaceTiming their bird friends just as much as parrots do.

Image by Matthew Modoono / Northeastern University (source)

I also learned from this paper that there is something called “Machiavellian Intelligence,” which refers to an animal’s ability to manipulate and deceive. High levels of Machiavellian Intelligence suggest that an animal can take the perspective of another being.

I am happy to report that chickens can lie and cheat with the best of ‘em. For example, they are known to make a food call even when there is no food around, as a way to attract females. That’s both a good intelligence indicator and also pretty messed up, so I’m glad that the females get keen to this tactic and learn to stop responding to the males who cry wolf. Intelligence all around!

Personality

The little bit of research we have into chicken personalities shows that, shocker, individual differences exist. One study noted how male chicks mediate their dominance status through differences in boldness, activity/exploration, and vigilance.

But mainly, Marino points to anecdotal evidence from chicken owners and sanctuaries. As she puts it, “There is an abundance of anecdotal evidence for individual personalities in chickens from sanctuaries, small farmers, and people who keep backyard chickens.”

As someone who volunteers at a sanctuary, I can vouch for this. I don’t spend a ton of time around the chickens, but each one of them is well known by the main staff for having individual desires, needs, and quirks.

Doesn’t it just feel like she has internal experiences? I have the opposite intuition as Herzog. (source: tiny hooves sanctuary)

A message shared on Slack by a sanctuary volunteer after a chicken passed away puts a fine point on it: “That little sweetheart had the biggest, gentlest personality! 🩷 Loved every second with him and so thankful to have met such a sweet, warm, loving soul.”

Bonus chicken biology facts

These facts are not all about cognition, but I found them fascinating and want to jam them into the review anyway:

• There is no evidence that domesticated chickens are less smart than their wild counterparts. This is because we selected them for things like fast growth and egg producing capacity, not anything to do with their minds.

• Chicken beaks are very important to them and highly sensitive, more like a human hand than a piece of inert cartilage. “At the end of the beak is a specialized cluster of highly sensitive mechanoreceptors, called the bill tip organ, which allows chickens to make fine tactile discriminations.” Yet another reason why it’s awful that factory farmed chickens get their beak tips cut off.

• They can see more colors than humans, they can detect magnetic fields, and they have exquisitely sensitive hearing abilities

Plot twist: Are chickens birds?

They have feathers and wings and beaks and whatnot. People should think chickens are as bird-like as they come.

But no. Marino points out that, “When asked to rate the typicality of chickens as a member of the more general category of birds, raters usually give chickens a low score, indicating that they are not considered typical birds.” They are thought to be unintelligent and to not have sentience, factors which conveniently make an animal more likely to be eaten. If you are considered dumb, unthinking, and unfeeling, it’s a short hop to making you a food commodity.

This separation of chickens into their own, dumber category has negative consequences for their wellbeing. If we thought of them like crows or magpies or ravens, instead of as unthinking commodities, we might be less inclined to cage them by the billions and cause them extremely high levels of suffering.

With learning and exposure, that can change. The paper includes a wonderful study where college students were asked their opinions of chickens pre and post spending time personally training a chicken. The results were heartwarming from an animal advocacy perspective.

Relative to their initial perceptions of chickens as slow learners, the students’ attitudes shifted to viewing them as intelligent and emotional animals with individual personalities […] Boredom, frustration, and happiness were the emotional states with the greatest shifts in student attitudes post-training.

I hope that more people can encounter Marino’s work and get just a taste of what those students experienced.

We slaughter 70 billion chickens each year after raising them in often brutal conditions. Maybe raising the moral status of this sensitive, intelligent, and unfairly maligned bird could make a small dent in that.

1. I learned of one such book only because it was cited by Thinking Chickens. It’s called The Behavioural Biology of Chickens. Marino says it is “a much more comprehensive and wide-ranging description of studies of chicken cognition and behavior.” Unfortunately it costs $59, maybe I need to put it on my holiday gift list.

2. The intrepid researchers at the Rethink Priorities Institute are on the case. They wrote 20,000 words on the subjective experience of time. In short, we don’t know the extent to which animals perceive time differently, but “there’s a ~70% chance there are characteristic differences in the subjective experience of time across species.”

3. Another bit on chicken empathy and emotional processing I found fascinating — the babies modulated their responses to getting hit by aversive air puffs based on looking at their mothers. Those with more chill moms acted more chill themselves. “These findings suggest that there are different ‘maternal styles’ in mother hens which may be based upon differences in personality traits. Moreover, the social buffering observed in this study is not dissimilar to the phenomenon of ‘social referencing’ in humans and other complex mammals, whereby the juvenile looks to the parent to determine how to respond emotionally to various situations.”