United Poultry Concerns January 30, 2004

Knowing More About Natural Poultry Behavior Can Lead To Better Care

By Karen Davis, PhD, President

"It should be realized that even vastly improved intensive systems are unlikely to meet the cognitive demands of the hitherto underestimated chicken brain."

-- Dr. Lesley J. Rogers, The Development of Brain and Behaviour in the Chicken , p. 213.

The belief that factory-farmed chickens, turkeys and ducks have lost their natural behaviors and are content to live in crowded and unstimulating environments is contradicted by contemporary avian science and by the variety of natural behaviors displayed by these birds at farmed animal sanctuaries. Chickens rescued from battery-cages sunbathe, dustbathe, forage, perch, run about the yard, and socialize in small groups. Hens scratch out nests in the straw in which to lay their eggs and "fuss" over their eggs in secluded corners of their house and yard.

Turkeys and chickens who have been bred for meat show normal patterns of behavior when they are young; as they get older they become more sedentary due to overly heavy breast muscle tissue, painful lameness in their hip joints (Danbury; Duncan), and metabolic disorders that affect the capacity of their hearts and lungs to function normally and that can lead to heart attacks at an early age. Ducks bred for meat and foie gras production are likewise burdened by overweight (ducks raised for foie gras are force fed huge amounts of food by having metal pipes rammed down their throats three times a day for a month before they are killed), and by health problems resulting from the lack of water that waterfowl need (Ducks & Geese). Provided with water, ducks from factory farms spend a large part of each day swimming, getting in and out of the water, and rinsing their eyes. Frequent eye-rinsing is necessary to keep ducks' eyes healthy and to prevent opthalmia, or "sticky eye" - a disease that is "most prevalent among ducklings that are raised indoors" (Holderread, 130-131).

Following is a brief overview of welfare issues and improvements affecting 1) hens kept in cages for egg production; 2) birds bred for meat production; 3) parent flocks of birds bred for meat production.

Hens Kept in Cages for Egg Production (UPC Public Comments, 21-26)

Caged hens are deprived of an environment suited to their nature as foraging animals with wings, legs, horny toes for scratching the earth, full-spectrum color vision, and other evolved characteristics that distinguish them as groundnesting birds with well-defined, scientifically characterized patterns of interest, behavior and activity. Caged hens are unable to forage (to peck and scratch at the earth with their claws and beaks), to dustbathe, to sunbathe, to perch, to stretch their wings, to walk or to run. Even on wire floors, their need to dustbathe is so strong that hens will go through the motions of dustbathing, which for chickens and turkeys is the hygienic equivalent of a waterbath or shower for humans. If hens are given access to litter material (earth, straw, peat, or sand), "They do it over and over again" (Turner, 35-36).

Biologist Marian Stamp Dawkins explains that "[I]f hens that have been kept all their lives on wire floors with no sight or contact with anything that could be scratched or raked over are suddenly, at the age of 4 months, given access to a floor of wood-shavings or peat, even these naïve hens have an immediate and strong preference for these more natural floors over the wire ones, which is all they have known until then. They dustbathe, eat particles of peat and scratch with their feet. It is not just the extra comfort afforded by a soft floor that attracts them but all the behaviour they can do there as well" (Dawkins, 153).

Exploratory and foraging behavior is important to chickens and turkeys. The birds use their beaks like a sensitive hand to explore and manipulate objects as well as to find food and eat (Rogers, 95). Chickens search for food by scratching with their claws and pecking vigorously at the ground. They "work" an area, constantly moving about, turning over leaves and raking up the earth looking for seeds, insects and other edibles, including the small stones they ingest to grind up the food in their gizzard, a process that, for them, is "teeth."

According to scientists, "Pecking is a precise, high-tech activity," requiring good coordination with the eye. In natural conditions chickens spend between half and 90% of their time foraging, making up to 15,000 pecks a day (Turner, 22-23). Feather-pecking and "cannibalism" occur in environments that frustrate the behavioral needs of foraging birds. In cages, "feather pecking occurs particularly in the afternoon when hens have finished feeding and laying eggs, and have little else to do" (Nicol & Dawkins, 50).

Instead of burning off a portion of the beak (and duck's bill), which is filled with sensitive nerves to the very tip, as is now done by the egg industry, the turkey industry, the duck industry, and producers of male birds used for breeding (Davis 1996, 65-72; UPC Public Comments, 36-41), "poultry farmers should provide pecking materials not only because hens [all of these birds] need to peck but because the consequences of deprivation may be fatal" (Nicol & Dawkins, 50). Currently, the US Department of Agriculture's Agricultural Research Service is attempting to breed hens who peck less while investigating various housing alternatives for laying hens including cages with perches, nest boxes, and sand-bathing boxes (Scientists, 4). This so-called enriched cage, while containing a few token improvements, is too small, crowded and cluttered for the birds to move normally and to exercise. Cages for hens, sheds filled with cages like factory warehouses filled with shoeboxes, should be eliminated.

Chicken specialist Lesley J. Rogers describes the suffering of hens kept in cages, be they barren or "enriched" cages, in her book The Development of Brain and Behaviour in the Chicken .

Chickens in battery cages are cramped in overcrowded conditions. Apart from restricted movement, they have few or no opportunities for decisionmaking and control over their own lives. They have no opportunity to search for food and, if they are fed on powdered food, they have no opportunity to decide at which grains to peck. These are just some examples of the impoverishment of their environment. Others include abnormal levels of sensory or social stimulation caused by excessive tactile contact with cage mates and continuous auditory stimulation produced by the vocalizing of huge flocks housed in the same shed. Also, they have no access to dustbathing or nesting material.

Chickens experiencing such environmental conditions attempt to find ways to cope with them. Their behavioural repertoire becomes directed towards self or cage mates and takes on abnormal patterns, such as feather pecking or other stereotyped behaviours. These behaviours are used as indicators of stress in caged animals. (Rogers, 219)

If hens are going to be kept for eggs, they should be kept in roomy, well-ventilated enclosures with easy outdoor access to a true "range" environment where they can perform most if not all of the natural behaviors that interest and define them as chickens. Dr. Lesley Rogers, a specialist in chicken cognitive behavior, writes: "I would argue that genetic selection has favoured chickens that can live in farmyard free-ranging conditions in contact with humans and other species, but not in battery cages" (219).

Birds Bred for Meat Production (UPC Public Comments, 26-30, 32)

Selective breeding for fast growth and heavy breasts has resulted in painful lameness and heart disease in birds bred for meat (Gentle, 1992; Danbury et al., 2000; Turner et al. Davis 1996, Ch. 4). The birds grow so fast - at 6 weeks old birds who would normally weigh a pound weighs over 5 pounds - that their skeletal system isn't strong enough to support their body weight, and their hearts and lungs are overstressed in trying to supply the excessive demand for oxygenated blood to the peripheral body tissues. High mortality in young "broiler" chickens and turkey poults is a constant theme of the poultry industry (Veterinary Meeting; Birds Exploited).

Chickens bred for meat are kept in sheds so crowded, with 20,000 or more birds, that by the time they are a month old, they can hardly move. The manure-filled floor litter (sawdust or pine shavings mixed with the birds' droppings) causes painful breast and hock joint sores, and toxic air pollution. The feces-saturated litter, on which the birds sit and stand continuously, favors the growth and multiplication of pathogens - disease organisms such as Salmonella enteritidis and Campylobacter jejuni ; and the decomposition of uric acid (nitrogen) in the droppings of thousands of birds crowded together fills the sheds with excretory ammonia fumes that burn the birds' eyes and respiratory tracts, enter their bloodstream, and depress their immune systems, reducing or eliminating their ability to resist the inflow of disease organisms (Davis 1996, 97-98; UPC Public Comments, 20-21).

In the increasingly used "solid-wall" and "tunnel ventilation" poultry sheds, airflow is automated and the houses are frequently constructed so as to exclude all natural sunlight. The walls are solid and the birds have only the dimmest of light, to allow them to eat and drink. As a result of the genetics, the low-grade feed intended only to bulk up the birds' weight quickly and cheaply and that includes the bovine nervous tissue that harbors mad-cow disease prions (Davis, 2003), and the dark unwholesome housing, "Birds at 5 weeks old can hardly stand because their legs are so weak and with no natural light or exercise their joints are too soft to carry the weight" (Forsberg cited in UPC Public Comments, 26).

The dimly lighted interior of the sheds reduces the movement of the birds around the house to getting up to eat and drink, then sitting down again. Opening the doors, farmers say it is difficult for them to see the birds and that sudden light or a flashlight frightens the birds into piling up, causing injuries and suffocation. Power outages and mechanical failures can, and do, kill off entire houses of birds (Clouse cited in UPC Public Comments, 27).

Parent Flocks of Birds Bred for Meat Production (UPC Public Comments, 31-36)

Parent flocks - the "breeders" of chickens, turkeys, and ducks - embody the complex maladies of fast rapid growth including mating disabilities. They suffer from malfunctioning ovaries, breathing difficulties, fertility problems, weak hearts, and more. To compensate, companies raise the birds in semi-darkness, in "blackout houses," and keep them on semi-starvation rations designed to control their weight and restrict their food intake by withholding a whole day's ration every other day. When food is restored, chickens rush to the feeders, often injuring their feet and other parts of their bodies in their desperation to eat. Bacteria invade the tissues and bloodstream following these injuries to the skin, especially of the feet, which are already embedded and incrusted with feces-caked litter and pathogens.

Food-restricted birds gorge themselves when the troughs are refilled. On days when food is withheld, the birds peck at spots on the floor, and to relieve their hunger they drink more water, which is also restricted because of the added mess it makes. Increased aggression in male birds towards female birds in chicken breeding flocks leads to hens being badly injured, fearful, and even killed by the males (Duncan; Mench 2002). Male and female turkeys are raised in separate sheds, where they are "milked" of their semen and artificially inseminated by teams of men who wrestle the birds to the ground to manipulate their genitals (Davis, 2001, 84-85, 97).


Forced rapid growth of birds bred for meat should be prohibited, as should raising the birds in filth and darkness as is currently done. Force feeding of chickens, turkeys and ducks, and food deprivation (forced molting) of hens used for egg production and "meat-type" breeding flocks of chickens, turkeys, and ducks, should be prohibited (UPC Public Comments, 5-18). Birds raised for meat and hens used for egg production suffer from a lack of sensory and mental stimulation, physical activity, and bodily comfort. Reducing animals to mere "behaving organisms" and "productive units" is not animal welfare. That a profitable number of birds out of tens of millions can survive to the young age of five weeks to a year or two does not prove welfare, as the poultry and egg industries would have us believe.

Millions of birds die before slaughter, and of the nine billion plus birds who live long enough to be slaughtered each year in the United States, millions are diseased, injured, and half dead (moribund) of undiagnosed causes by the time they reach the slaughterhouse. Birds raised for food never get pain relievers. Individuals, as such, are never considered. Poultry welfare specialist Joy Mench explains the fallacy of using mass productivity of animals as an indicator of individual animal welfare:

It is now generally agreed that good productivity and health are not necessarily indicators of good welfare. In large part, this is due to the way in which these measures are defined and manipulated within the commercial productive environment. Although stress is known to result in suppression of growth and reproduction as well as in decreased immunocompetence, these effects occur at the level of the individual animals. Productivity, however, is often measured at the level of the unit (e.g. number of eggs or egg mass per hen-housed), and individual animals may be in a comparatively poor state of welfare even though productivity within the unit is high.

Additionally, health and productivity may be maintained or enhanced through genetic and environmental manipulations which do not necessarily improve the welfare of the individual. Broilers [birds bred for meat], for example, have been bred for a high rate of growth, which may also be associated with physical disability and skeletal weakness. The movement restriction imposed by these disabilities and by crowding further enhances growth rate, as does the administration of subtherapeutic levels of antibiotics. In this case, productive performance has been enhanced at the expense of health and by limiting the behavior and movement patterns of the animal (Mench 1992, 108-109).


Birds Exploited for Meat:

Clouse, M.A. A Primer on Tunnel Ventilated Poultry Houses, June 20, 2003. Cited in UPC Public Comments.

Danbury, T.C., et al. 2000. Self-selection of the analgesic drug carprofen by lame broiler chickens, Veterinary Record 146: 307-311.

Davis, K. Prisoned Chickens, Poisoned Eggs: An Inside Look at the Modern Poultry Industry . Summertown, TN: Book Publishing Company, 1996.

Davis, K. More Than a Meal: The Turkey in History, Myth, Ritual, and Reality . NY: Lantern Books, 2001.

Davis, K. Assume No Animal Products Are Safe, Jan. 14, 2004:

Dawkins, M.S. Through Their Eyes Only? The Search for Animal Consciousness . NY: W.H. Freeman, 1993.

Ducks & Geese: http://upc-online.org/ducks

Duncan, I.J.H. 2001. Animal Welfare Issues in the Poultry Industry: Is There a Lesson to Be Learned? Journal of Applied Animal Welfare Science 4.3: 207-221.

Forsberg, V. Email to UPC, March 31, 2003. Cited in UPC Public Comments.

Gentle, M.J. Pain in birds. 1992. Animal Welfare 1:235-247.

Harrison, R. The myth of the barn egg, New Scientist , Nov. 30, 1991, 40-43.

Holderread, D. Raising the Home Duck Flock: A Complete Guide . Pownal, VT: Garden Way Publishing/Storey Communications, 1992.

Mench, J.A. 1992. The Welfare of Poultry in Modern Production Systems. Poultry Science Review 4: 107-128.

Mench, J.A. Broiler breeders: feed restriction and welfare. World's Poultry Science Journal 58.1: 23-29.

Nicol, C. and M.S. Dawkins. Homes fit for hens. New Scientist , March 17, 1990, 46-51.

Rogers, Lesley J. The Development of Brain and Behaviour in the Chicken . UK: Cab International, 1995.

Scientists Using Group Selection for Cage Layers, Egg Industry Jan. 2004, 4.

Turner, J. Stop-Look-Listen: Recognising the Sentience of Farm Animals . Compassion in World Farming Trust, 2003. www.ciwf.co.uk . Available from United Poultry Concerns.

Turner, J. et al. The Welfare of Broiler Chickens in the European Union . Compassion in World Farming Trust, 2003. www.ciwf.co.uk .

UPC Public Comments to the New Jersey Department of Agriculture Regarding: Humane Treatment of Domestic Livestock , June 27, 2003:

Veterinary Meeting Looks at Poultry Health, Poultry Times , Oct. 27, 2003.

Further Reading Online

Battery Hens:

"Broiler" Chickens:

The Experimental Use of Chickens and Other Birds in Biomedical and Agricultural Research:

The Plight of Birds in the Poultry and Egg Industry:

Poultry Slaughter

United Poultry Concerns is a nonprofit organization that addresses the treatment of domestic fowl in food production, science, education, entertainment, and human companionship situations and promotes the compassionate and respectful treatment of domestic fowl. www.upc-online.org


United Poultry Concerns, Inc.
PO Box 150
Machipongo, VA 23405-0150
FAX: 757-678-5070

Home | What's New? | News Releases | Action Alerts | PoultryPress | Resources | Merchandise | Links | E-mail