Domestication of Poultry
Historically, all domestic chickens (Gallus gallus domesticus) were thought to have derived from the red jungle fowl (Gallus gallus). However, genetic analyses suggest there might have been more than one domestication event, and other species, such as the gray jungle fowl (Gallus sonneratii), could also be progenitors (1).
Genomic analyses suggest that the lineage of domestic chickens diverged from the lineage of wild ancestors 6,200–12,800 years ago. However, the earliest evidence for initiation of a domestication process dates to approximately 1650–1250 BCE (2, 3). Chickens are believed to have been domesticated originally for religious reasons and for cockfighting, not as a food source.
The ancient Romans were the first civilization known to have used chickens for agricultural purposes. After the fall of the Roman Empire, few, if any, of these agricultural breeds survived. It was not until the 19th century that chickens were used as food animals again.
Regardless of their lineage, and despite centuries of domestication, chickens today have almost the same basic behavioral repertoire as their ancestors. Modern factors, such as housing and flock size (commercial versus backyard flocks), have shown little effect on chicken behavior, except that chickens in large commercial flocks might not have the space or resources to perform particular behaviors, such as wing flapping or dust bathing.
Domestic turkeys (Meleagris gallopavo domesticus) were domesticated from wild ancestors (Meleagris gallopavo) in North America approximately 2,000 years ago but were not selected for meat production until the 20th century.
Ducks were domesticated around 2000 BCE, and most of the modern domestic breeds derive from the mallard duck (Anas platyrhynchos) and Muscovy duck (Cairina moschata). As with chickens, modern duck breeds show few behavioral differences from their ancestors.
General Behaviors of Poultry
Foraging in Poultry
Both chicks (starting at 3–4 weeks old) and adult poultry forage. Foraging is the searching component of feeding behavior, in which birds scratch through a substrate and look for bits of food in what they uncover. Ducks can forage in water.
Foraging is a highly motivated behavior, and poultry spend a large percentage of their time foraging. Birds forage even when they are given feed freely, work for the opportunity to forage, and perform foraging behavior even in the absence of a substrate, such as in a cage.
Perching in Poultry
Perching—seeking higher places to stand, sit, or rest—is another highly motivated behavior of poultry. Chicks begin perching at approximately 10 days of age.
Chickens are especially motivated to perch at night because this behavior is an antipredator defense.
For chickens, perch design (eg, size, material, and height) is important. Studies have shown that chickens prefer perches that are elevated, round or square, and about 4 inches in diameter. The lowest perch provided should be 18–36 inches off the ground. Higher perches should be offset to avoid soiling of lower-perched birds. There should be enough perch space for all birds to perch simultaneously (approximately 6 inches pf perching space per bird). Softer materials like plastic, rather than metal, are typically preferred. Wood can be used, but it can be difficult to clean and disinfect properly.
Heavy-bodied birds, like ducks, turkeys, and broilers, might prefer an elevated platform and might require a ramp for access.
Dust Bathing in Poultry
Dust bathing helps chickens maintain proper feather condition. To dust-bathe, a chicken creates a depression in soft, dry material (dirt, sand, wood shavings, etc); rubs and scratches the material into its feathers; and then shakes the material out. This process allows the substrate to absorb excess oils from the feathers and skin of the bird.
Dust bathing is performed by both adults and chicks (starting at 1–2 weeks old).
In addition to being a plumage maintenance behavior, dust bathing is a social behavior and is one of the few affiliative behaviors (promoting social cohesion and positive interactions) that chickens perform.
Males and females engage in dust bathing together, often touching.
Unlike other poultry, ducks do not dust-bathe, but rather perform water bathing as an analogous behavior.
Nesting in Poultry
Only sexually mature hens engage in nesting behavior. Nesting behavior is controlled by hormones and consists of a sequence of actions to ensure that a nest is available when the hen is ready to lay her egg:
Nest searching. The hen looks for a suitable nesting area, exhibiting pacing behavior or inspecting several nest box options.
Settled nesting. The hen settles into the nest, perhaps creating a small depression, and waits to lay her egg. In commercial settings, this step might be skipped, and hens are often observed pacing until the egg is laid.
Egg laying. Some hens remain sitting on the egg after it is laid. Allowing hens to sit on eggs increases the likelihood of broodiness, in which hens remain on eggs to incubate them.
Nesting is usually a gregarious behavior, with several hens nesting at the same time and in the same nest box.
Sickness Behavior in Poultry
All poultry species display similar behavior when they are sick. Because poultry are prey species, they tend to hide signs of sickness until they are very ill.
Early detection of illness through observation of behavior is essential. Birds that are sick generally show decreased production, whether in egg yield or growth. They also decrease feed and water intake. These signs are early indicators of sickness.
A sick bird is typically withdrawn, often with its head pulled into its shoulders, its eyes closed, and looking droopy. Birds with respiratory disease also might shake their heads, sneeze, or cough.
Social Structure and Behavior of Poultry
Social Structure of Chickens
Chickens are highly social. Feral chickens typically form small flocks, with one male and several females. Groups that have little opportunity to disperse, such as backyard flocks, often consist of a couple of males and females.
Chickens form a social hierarchy, often referred to as the "pecking order.” This hierarchy is made up of dyads, with one bird dominant and the other subordinate. All birds in a flock have a pairing like this with every other bird in the flock. Chained together, these relationships form a hierarchy from most dominant (highest rank) to most subordinate (lowest rank).
These pairings are typically decided through aggression, with the subordinate bird receiving a peck to the head (hence the term "pecking order"). Once established, the hierarchy is very stable, and rank is reminded with body gestures rather than aggression. As birds age, they may decrease in rank.
Stress or changes in the environment, such as the addition or loss of a flock member, can cause the hierarchy to collapse. In these situations, paired relationships must be reestablished, and the same ranking may not necessarily occur.
Social Structure of Turkeys and Ducks
Turkeys generally live in sex-segregated flocks; however, the sexes might mix outside of breeding season. Commercial turkeys are generally raised in all-male and all-female flocks.
Wild ducks live in large aggregations with mixed sexes, and birds pair off or form small groups during breeding season. Commercial ducks are typically raised in large mixed-sex groups.
Sexual Behavior in Poultry
When males are present, they show courtship behavior toward hens. Often this behavior is initiated when a male picks up a small bit of food (or a nonfood item, such as wood shavings or grass) and makes a food call. The call attracts hens to be physically near him.
The male might then approach a hen with a wing down, sidling up to her (a behavior often referred to as "waltzing"). If the hen is receptive, she will couch and allow the male to mount her and copulate with her.
The higher the rank of a male, the more successful he is at mating. In flocks with many males, low-ranking females might be forced to copulate with low-ranking males. Females can be injured in these circumstances, and males should be separated into bachelor flocks.
Turkeys form a lek, in which multiple males show off and compete for females. Females choose which male to mate with. Because of the large size of commercial turkey breeds, artificial insemination is used on breeder farms.
Ducks do not form long-term sexual pairings, and like roosters, drakes often force copulation on females.
Brooding and Chick Interactions in Poultry
Hens typically brood 7–10 eggs in a nest. Incubation does not begin until the last egg is laid, ensuring that all chicks in a brood should hatch around the same time.
Before hatching, there is some communication between the chicks and the hen, and between chicks. Chick calling can stimulate other chicks to start hatching or speed up the hatching process.
Once their chicks have hatched, hens often take them away from the flock for a few days to a week.
Chickens, turkeys, and ducks are precocial at hatch, able to fend for themselves fairly soon after hatching. Parental care includes providing warmth, showing chicks where to find food and water, and protecting chicks from predators.
Key Points
Poultry perform several highly motivated behaviors: foraging, perching, dust bathing, and nesting.
Chickens naturally form small social groups that establish a stable hierarchy.
Turkeys live in all-male and all-female groups; ducks live in large social aggregations.
Male chickens court females, and higher-ranking males have more mating success. Low-ranking male chickens and ducks force copulation with low-ranking females.
All poultry species show some parental care.
For More Information
Appleby MC, Mench JA, Hughes BO. Poultry Behaviour and Welfare. CABI; 2004.
Mench JA, ed. Advances in Poultry Welfare. Woodhead Publishing; 2017.
Nicol CJ. The Behavioural Biology of Chickens. CABI; 2015.
References
Lawal RA, Martin SH, Vanmechelen K, et al. The wild species genome ancestry of domestic chickens. BMC Biol. 2020;18(1):13. doi:10.1186/s12915-020-0738-1
Peters J, Lebrasseur O, Irving-Pease EK, et al. The biocultural origins and dispersal of domestic chickens. Proc Natl Acad Sci U S A. 2022;119(24):e2121978119. doi:10.1073/pnas.2121978119
Best J, Doherty S, Armit I, et al. Redefining the timing and circumstances of the chicken’s introduction to Europe and north-west Africa. Antiquity. 2022;96(388):868-882. doi:10.15184/aqy.2021.90
