How intelligent are chickens?

The objection

“Why agonise over chickens? They’re basically biological machines, no inner life, nothing going on upstairs.”

The answer

Two reviews of the experimental research reached the opposite verdict. Lori Marino concluded in a 2017 review that chickens are as cognitively, emotionally and socially complex as most other birds and mammals in many areas [1]. She was writing from the Kimmela Center for Animal Advocacy for The Someone Project, a research initiative sponsored by the US farm-animal advocacy group Farm Sanctuary, and the American charity the ASPCA part-funded the work [1][10]. Laura Garnham and Hanne Løvlie, biologists at Linköping University in Sweden, called the birds’ behaviour and cognitive skills sophisticated (2018) [2]. Marino reported no evidence that breeding for growth and egg-laying had substantially changed chickens’ cognitive or perceptual abilities [1], although a 2009 study found White Leghorn laying hens poorer at a spatial learning task than red junglefowl, their wild ancestor [9].

Can chickens count?

Chickens can count in a basic way: chicks a few days old keep track of small quantities. In experiments by Rugani and colleagues (2009), chicks three or four days old went to whichever of two screens hid more objects, and still chose correctly after objects were moved one at a time from one screen to the other, which meant following a series of additions and subtractions [3]. In a later study (2015), three-day-old chicks linked smaller numbers with the left and larger ones with the right, which the authors likened to the mental number line in people, a line whose links with culture they called unclear [4]. Marino notes that this research leans heavily on imprinting, so it mostly involves very young chicks, and in 2017 she called work on how these abilities carry into adulthood urgently needed [1].

Can chickens reason and show self-control?

Hens appear capable of simple reasoning and of some self-control. In a 1996 study described in both reviews, hens that watched a stranger beat a familiar hen who outranked them declined to challenge the stranger, while those that saw the familiar hen win attacked the stranger about half the time [1][2]. Marino (2017) calls this consistent with transitive inference, working out that a stranger who beats a hen’s superior would beat the hen too, while noting that the nature of such inference in animals is still debated [1]. In a 2005 study by Abeyesinghe and colleagues, hens chose 22 seconds at a feeder after a 6-second wait over 3 seconds after a 2-second wait [1][8]. They did not hold out when the larger option was 7 seconds after a 6-second wait, or 22 seconds after a 22-second wait [8].

Do chickens talk to each other?

Chickens communicate with a large repertoire of calls, some of which carry specific meanings [1][2]. Both reviews cite a 1987 classification by Nicholas Collias that counted around 24 distinct calls in the red junglefowl, the chicken’s main wild ancestor [1][2]. Roosters give one alarm call for a bird of prey overhead and another for a predator on the ground, and the rest of the group responds to each appropriately [1]. Calls also depend on who is listening: a subordinate male who finds food tends to leave out the loud call when a dominant male is around, and some males make food calls when there is no food, which draws hens closer [1][2].

Do chickens have feelings?

Chickens show fear, anticipation and a specific response to their own chicks’ distress, all measured in experiments [1][5]. Laying hens that learned which sounds came before food or a squirt of water paced more before the squirt and showed comfort behaviour such as preening before the food (Zimmerman and colleagues, 2011) [1]. In a study by Edgar and colleagues (2011), hens grew more alert whether a puff of air was aimed at them or at their chicks, but their heart rate rose and they gave maternal calls only when it hit the chicks, even though the chicks made few distress calls; the authors concluded that hens have at least one of the essential underpinnings of empathy [5]. In 2024 the New York Declaration on Animal Consciousness, since signed by more than 600 neuroscientists, biologists, philosophers and others, stated that there is “strong scientific support for attributions of conscious experience to other mammals and to birds” [6].

Marino cautions that similar behaviour need not mean the same mental machinery across species [1], and none of this puts a hen’s mind on a level with a person’s. The objection, though, was that nothing goes on inside a chicken at all, and the experiments describe a bird that tracks quantities, reads its flock’s pecking order and is distressed by its chicks’ discomfort. About 78.5 billion chickens were slaughtered for meat worldwide in 2024, according to UN FAO figures [7].