Is my chicken sick? (Poultry Welfare)

(Editor’s note: Dr. Shawna L. Weimer is an assistant professor with the University of Maryland. Ashlyn Snyder, a University of Maryland graduate student is a co-author of this column.)

Sickness behavior is the way animals recover from disease.
Sick chickens can be difficult to identify because, as a prey species, they rely on their instincts to hide sickness behavior because hiding signs of sickness tells predators that they are not an easy meal.
What is Normal Chicken Behavior? What Does it Look Like?
It is important to know what is normal for your birds. Normal behaviors are species-specific, displayed under natural conditions, occur in nature, and happen out of the animal’s own interest.
Some natural chicken behaviors that are thought to be positive indicators of welfare include preening, dust bathing, foraging and perching.
Chickens are a flock species and need to be in groups to promote social behaviors, such as play. Social hierarchy (pecking order) is important and helps maintain social balance.
Time spent engaging in natural behaviors will vary between breeds and individual chickens and will decrease when the birds are sick.
Preening is a form of grooming. A chicken will run its beak through its feathers to distribute oils and realign the feathers. Chickens enjoy preening each other and this helps maintain positive social bonds.
Dust bathing refers to a series of behaviors including pecking and scratching at a substrate (such as dirt) followed by sitting and wing flapping to gather and distribute dust particles, then laying and rubbing or rolling and shaking off the particles.
Dust bathing may help clean the feathers and remove external parasites and may occur as a social activity.
Foraging is an exploratory behavior that occurs when a chicken scratches or pecks at a potential food source (such as dirt or grass) even in the presence of freely accessible food.
Chickens are highly motivated to forage and it takes up the majority of their daily time budget.
Foraging may provide chickens with information about the environment they may utilize in the future, but it is also self-rewarding in that chickens may come across higher quality food items.
Chickens are socially motivated to forage and will forage more often in the presence of others.
Perching refers to a chicken sitting on surfaces off the ground.
Chickens often perch close to the ground and roost on surfaces at greater heights.
Perching is typically performed for rest but also allows chickens to escape ground-dwelling predators and aggressive peers.
Roosting refers specifically to sleeping while perching.
Play can be either a social activity or individual activity and includes several behaviors such as sparring, food-running, and frolicking.
Sparring is play fighting without intent to injure and may involve jumping with light kicking or pecking and stand-offs.
Physical contact during sparring isn’t forceful.
Food-running involves chasing another bird with a piece of feed or large object.
Frolicking is spontaneous activity such as running, jumping or wing flapping.
Typically, these behaviors decrease with age.
Behaviors indicating sickness and how they contribute to recovery
Sickness behaviors in chickens include a wide variety of behaviors, from subtle to clear clinical signs of illness.
Sick animals behave in a way that promotes healing and recovery. Often, this involves prioritizing different behaviors from normal.
These trade-offs help reallocate resources and energy to fighting infection, particularly when the bird has a fever.
Fever both suppresses and destroys pathogens during infection and is aided by behaviors and metabolic changes that reduce heat loss, increase heat production and conserve energy, such as fatigue. Sickness behavior can also appear as a reduction in frequency, duration or intensity of normal behavior.
Dullness or depression is when the bird has reduced interest in the environment and interactions with conspecifics, including, but not limited to, play, dominance and reproductive behaviors.
Fatigue (lethargy) is when the bird is not standing or moving around as much as it normally does. More time is spent sitting or resting, and it may often keep its eyes closed. Reduced activity preserves resources by limiting energy expenditure.
Inattentiveness is when the bird does not respond to changes or stressors, such as human presence and sudden sounds or motions.
Anorexia is when the bird is eating less than normal. Anorexia directly suppresses infection by reducing the nutrients available for pathogens to use toward replication.
Isolating is when the bird does not interact with other chickens as much as previously and may self-isolate by spending more time away from the rest of the flock.
Hunching is when the chicken is standing, with ruffled feathers, neck pressed into its chest and head down. The bird may be drooping its wings with eyes closed.
Huddling is when chickens group together to conserve body heat during cold stress or fever.
Chicken welfare: What can we do?
Sickness management is important to the welfare of our chickens.
Identify chickens with behavioral or physiological signs of illness and evaluate the need for treatment.
Chickens that may become sick or are sick should be isolated to provide specialized care and to prevent the spread of disease to healthy chickens.
Establish a relationship with a reliable local veterinarian, call your vet for a diagnosis, and treat your chickens as directed.
Severely ill or injured chickens are unlikely to survive and may need to be euthanized.
Prevent sickness in your chickens by knowing what distresses your chickens and how they behave during stressful events. Manage and reduce stressors, as they are linked to suppress the immune system. Always practice biosecurity and regularly clean everything in the housing area.
Consider vaccinations to prevent disease and quarantine new birds before introducing them into your flock to ensure they are healthy and to prevent disease transmission into your flock.