Cognitive abilities of chickens surpass those of cats, dogs and even some primates. They can count, know simple geometry and solve problems that can't be handled by small children.
In their natural environment they form complex social hierarchies. Hens recognize faces and hierarchy levels of up to 100 different hens thanks to remarkably good memory.
People who have spent some time with hens know that each individual has its personality: some birds are sociable and fearless, while others are timider and alert, some hens prefer company while others are grumpy or even somewhat aggressive.
Hens have a habit of hugging themselves when falling asleep. They show empathy towards other hens, help the weak, defend their flocks, "mourn" the loss of their members.
Hens experience REM phases during their sleep, so scientists believe they have dreams just as we do.
Chickens use over 200 different sound signals for communication, and they customize their style of "speech" to the audience. They formulate a message in a different way to a single individual, different to a larger group of hens, still different to the whole herd.
Hens begin to communicate with their children even before they hatch. The embryo in the egg is able to release distress signals, after which the mother responds or – if she is away - returns to the nest.