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.
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.
Birds bred for egg production
Chickens in battery cages are cramped in overcrowded conditions. Apart from restricted movement, they have few or no opportunities for decision making 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 dust bathing 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.
Birds bred for meat production
Selective breeding for fast growth and heavy breasts has resulted in painful lameness and heart disease in birds bred for meat. 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.
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.
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. Reducing animals to mere "behaving organisms" and "productive units" is not animal welfare.
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.