Chickens are amazingly clever and they understand a lot of what is happening in the world around them, according to a new review of scientific literature on the subject.

The study formed the basis of a white paper issued by the US animal protection organization "Farm Sanctuary." It found that chickens, with their cognitive and emotional abilities, can take in just as much as small children, primates or certain birds that are usually thought to be far more intelligent.

With its initiative "The Someone Project," the organization hopes to generate empathy for farm animals, which have a history of living alongside humans for tens of thousands of years. It's also intended as an appeal against battery farming.

Behavioral researchers Lori Marino and Christina M. Colvin analyzed numerous publications to compile a meta-study from various researchers who were looking at chicken behavior. They found that the walnut-sized brain of a chicken was capable of more than might be expected.

For one thing, Marino reported in the scientific journal Animal Cognition, chickens are able to make logical conclusions of the sort that children are only able to master from about the age of seven.

"The very idea of chicken psychology is strange to most people," Marino wrote in the paper.

"Chickens are just as cognitively, emotionally and socially complex as most other birds and mammals in many areas."

A feeling for figures

According to Marino, a former senior lecturer at Emory University, Georgia, who now heads an animal advocacy center, chickens are "behaviorally sophisticated," "share some very basic arithmetic capacities," and "have distinct personalities."

According to one of the studies the pair looked at, even baby chicks can count. At the very least, newly-hatched birds are able to tell the difference between a larger set of object and a smaller set. This was shown in a test using yellow plastic eggs. 

Chickens also appeared to have a comprehensive ability to think in three dimensions, along with a certain ability to multitask. They can search for food at the same time as making perceptions about how friendly or unfriendly another animal might be - while also simultaneously scanning the skies for dangerous birds of prey.

Their most important sense organ, though, would appear to be the beak, with its phenomenal sensitivity to taste, smell and touch. Any injury to it would cause a significant amount of pain.

Empathy and ranking

Chickens have a considerable degree of self control. Studies have shown that they are able to refrain from feeding if it means that they will receive better food later.

Chickens are also conscious of their own social standing within a population. Their own rank in the hierarchy is clear to them. Essentially, chickens are able to reflect on their own being.

Communication among chickens is also very complex, the pair found. They have 24 different sounds and a large number of visual signals. They're able to perceive time intervals and make deductions about events in the future. They observe and learn from one another and are strongly influenced by the behavior of their mothers.

Feeling distress for others is no alien concept to chickens, either. When a gust of wind ruffles the feathers of their chicks, mother hens begin to develop the same symptoms of stress as their startled offspring. It appears, then, that chickens are capable of empathy - being able to understand the predicaments that other members of their species might find themselves in. It's a level of understanding that's only been seen in relatively few animals, such as primates and ravens.

Researchers have also been perplexed by the capacity of chickens for subterfuge and deceit. Lower-ranking males, for instance might try to lure a female with foraged food in the normal way, but at the same time they will forego the courtship calls that normally accompany the behavior. That way, they can help make sure the alpha male doesn't get to find out about the "romantic" rendezvous.

The most-eaten farm animal

The common chicken (Gallus gallus domesticus) stems from the red jungle fowl, a game bird from southeast Asia. There are more of them than any other domesticated animal in the world, with some 20 billion living in our midst - about three per person. About twice that number are slaughtered each year.

Most of the birds that we eat are reared intensively on battery farms. Many of them see no sunlight over the course of their short lives. They are not able to develop properly, being crammed into tight cages and many suffer injuries mutually inflicted on one another in the stressful environment.

"The available research on chickens is quite suggestive," said the white paper. "Even so, a fuller understanding of these fascinating creatures requires much more respectful, non-invasive study in naturalistic settings that allow chickens to express themselves and, in so doing, help us learn more about who they are.

"Inspired by what we do know about chickens, we hope for a future full of human-chicken relationships curious about and celebratory of what both species may share in common."