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Chickens Might Be Self-Aware. Yikes!

Apes, dolphins, 18-month-old human babies, and now roosters can all pass versions of the mirror test.

A rooster.
Heatmap Illustration/Getty Images

Like the question of what lies beyond the universe and what happens when we die, thinking too long or too hard about the implications of what it means if the things we eat have self-awareness can drive you a little mad. Certainly, it’s deeply uncomfortable to contemplate at length.

Take it from me: Earlier this year, I tried to weigh the ethical dilemma of eating more chicken — which would be vastly better for the planet, short of the impossibility of everyone becoming a vegetarian — and the fact that replacing beef and pork in our diets with more poultry would necessitate the slaughter of an additional 41 billion animals worldwide. Now, a new study out this week in the journal PLOS One has upped the stakes of my ethical conundrum: It appears that roosters can recognize themselves in a mirror, a test that researchers have long used to assess the self-awareness of animals and that has only been passed by the ones we consider “smart,” like whales, primates, dolphins, and elephants.

Roosters failed the traditional mirror test, which is passed when an animal investigates a paint spot on its body using a mirror, thereby proving it “recognizes” the image in the glass as its own reflection and not another animal of the same species. But animal behavior specialist Sonja Hillemacher of Germany’s University of Bonn devised an improved version of the experiment that would cater more to a rooster’s sensory experience of the world. Roosters “are known to cry out to warn each other when a hawk is circling overhead,” The New York Times writes. “But when they’re alone and a predator is near, they stay silent to avoid attracting attention.”

Hillemacher’s resulting experiment went like this, the Times explains (if you need a visualization, see fig. 3 here):

Ms. Hillemacher wrangled roosters and gave them time in an enclosure with a mirror, so they could get used to the experimental set-up. Because roosters warn others more reliably than hens do, the team chose to focus on them, but they believe the results of the test apply to all chickens. She then projected a hawk silhouette over the roosters to see how they’d react.

When another rooster was visible through a partition, the rooster that was the subject of an experiment cried out to warn the other of danger. When alone without a mirror, the bird stayed quiet. When another rooster was present, but blocked from view by a mirror, the test subject still tended to stay silent.

The researchers interpreted this behavior to mean that the rooster didn’t perceive its reflection to be another rooster, and felt it also showed that the birds were sensing each other with sight — not hearing or smell.

The self-awareness and “experience” of animals is a particularly contentious corner of behavioral science and ethics, at least in part because the psychological stakes are so high. Still, the Times is careful to note that while the study appears to indicate the possibility of rooster self-awareness, it is not likely to persuade everyone. The mirror test itself is considered an imperfect indicator of animal “intelligence” by some researchers.

But if I didn’t feel queasy enough about trying to reconcile the positives of more climate-friendly eating with the negatives of animal suffering, I sure do now! For example, pigs — which some people refrain from eating because of their intelligence — have not confidently passed a mirror test. At this point, chickens are the only animal in most people’s diets that have.

I don’t have all the answers, besides a perennial reminder that eating more plants = good. (Also, is this another point in favor of eating bugs???) Instead, I’ll leave you with the words of the researchers themselves:

“With over 19 billion individuals worldwide used for meat and egg production each year, chickens are the most widely used farm animal,” they write. “Despite their worldwide presence and use, only a few studies [have] addressed their cognitive capacities.”

Jeva Lange profile image

Jeva Lange

Jeva is a founding staff writer at Heatmap. Her writing has also appeared in The Week, where she formerly served as executive editor and culture critic, as well as in The New York Daily News, Vice, and Gothamist, among others. Jeva lives in New York City.


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