2024-04-28 19:05:57
Flushing the face with rage may seem like a uniquely human trait. But according to scientists from France, hens also blush during “negative situations of strong arousal”, writes Mail Online, quoted by BTA.
In a new study, one group of hens was fed a worm treat while the other group’s chickens were chased by shouting, grabbed and forcibly held by the researchers. All the while, cameras recorded the faces of the birds.
The scientists compared the two groups and found that the hens’ faces reddened the most when they were excited or anxious—that is, when they were being chased. The group of lucky hens that were fed a treat blushed in the face, but much less.
Chickens have many blood vessels near the surface of the skin on their faces, so the skin turns bright red when blood flow increases.
The study was conducted by researchers from the French National Research Institute for Agriculture, Food and the Environment (INRAE).
“This finding may help to assess the quality of the human-animal bond,” Delphine Sule, a researcher from the team, told Mail Online.
Facial flushing during arousal has already been observed in several other birds, such as blue and yellow macaws. To check whether the hens had a similar reaction, the French researchers observed six laying hens for three weeks. The birds were fed a tasty mealworm treat or were captured by the researchers and held with their wings folded for one minute. During this time, the hens were carefully recorded, collecting 18,000 different pictures of their faces. Using a computer program developed by the researchers, they were able to notice that the chickens blushed much more during periods of excitement.
“In our study, we found that hens also blush in positive situations of high arousal associated with reward and pleasure,” adds Delphine Soule. “But the strongest blushing was observed in negative situations of high arousal, for example when we forcibly grabbed and held the hens.”
It’s not known exactly why hens blush this way, but Sule suggests it may have a “signaling function” to show their emotional states to other birds.
At the same time, a paler face is a sign of “calm and contentment,” because resting hens are slightly flushed until something excites them.
The researchers were able to use this information to see how the hens adjust to humans over time.
A group of 13 kochki were gradually acclimated to humans over time, while another 13 were left to fend for themselves. The group that was acclimated maintained a lighter skin color, indicating that they were more relaxed when an experimenter was nearby. The researchers say it could be a test of the strength of the bond between humans and hens and show when the feathered are more comfortable around people.
“More generally, these new facial emotion markers could be used in other species of birds kept in captivity as part of conservation programs or as pets,” says Sule.
In their paper, published in Applied Animal Behavior Science, the researchers write that understanding birds’ emotional or “affective” states is key to “understanding their sensitivity”.
However, assessing the extent to which animals such as chickens experience emotions is extremely difficult.
Delphine Sule explains: “Determining emotional ranges in humans is in itself very difficult, with no real consensus among scientists so far. Even determining whether two human beings have similar emotional ranges is difficult and influenced by culture.”
All vertebrates, including birds, are believed to have the same six basic emotions: fear, joy, anger, disgust, sadness, and surprise.
Previous research has also suggested that hens may experience a kind of empathy, especially for hens whose chicks are distressed.
Feathered birds also display a wide range of emotions in their cries that can be relatively easily recognized by humans.