November 22, 2008

Animal behaviour and welfare: Poultry Part 1


Origin: Senses: Social behaviour

By Dr Clive Dalton

Poultry origin and behaviour
  • Modern poultry were domesticated fairly early in man's development from wild jungle fowl still found today in open forest habitats throughout the world. The ancestors of the domestic fowl soon learned to live with man in confined areas.
  • Domestication and early selection of these birds developed such traits as leanness, aggression, activity, pecking, leg slashing, social responsiveness and particular colours of feathers that were used for decoration.
  • In later historic times such as in the Roman Empire, egg and meat production received emphasis and was greatly improved.
  • The modern laying hen and broiler chicken have both attracted more concern about their behaviour and welfare than any other farm animal.
  • This is because of the intensive systems in which they are kept - seen as "factory farming" which has gained an international negative image.


  • Chick embryos respond to light as early as 17 days after the start of incubation.
  • A hen cannot rotate its eye very much but they can see a field of 300 , with a binocular field of 26.
  • Hens follow moving objects using the mobility of their head.
  • Their acuity (sharpness) is good and they have good distance vision.
  • They characteristically lift their heads before jumping and tests have shown that they can discriminate between squares, triangles and red and black dots.
  • Studies show newly-hatched chicks prefer to peck at blue objects rather than green or orange ones, although orange is preferred before green but not before red.
  • Chicks can differentiate between red-dyed liquid and blood. Blood was very aversive.
  • Chicks learn quickly to avoid coloured feed if it makes them ill, and prefer to peck at round rather than flat objects.

  • Not much is known about how important smell is to poultry.
  • Hens are not keen on food that smells of mould or is sour, so presumably smell is involved in this feed rejection.
  • It's suggested that birds can definitely smell blood.
  • Hens don't have an ear lobe but they have a well-developed ear.
  • Calls produced by hens range from 250 cpm (the broody hen "cluck") to about 3000 cpm (the distress call).
  • Studies confirmed hens can hear sounds as high as 8000 cpm.
  • Hens hear in a range from 60-11950Hz with highest sensitivity from 815-2000 Hz which is their normal hearing range.
  • Hens have about 340 taste buds mainly on the palate and floor of their oral cavity.
  • They are rather indifferent to sugars but can detect glucose to about 2.5% in solution.
  • They tolerate a range of acid and alkaline tastes, and are sensitive to and avoid salty feeds.
  • Taste determines whether a hen accepts or rejects a feed and similarly to water.
  • Hens can detect water temperature differences of 2.8 C. They will reject water that rises 5.5 C above their body temperature although they will readily drink freezing water.
  • Stroking, rotating and turning hens upside down will immobilise a hen for various periods of time.
  • In this state, although fully alert to their sensory surroundings, they can be conditioned or gentled to humans or other frightening objects.
  • After return to normal, they will show reduced fear to the conditioned object.
  • Touching the back of a hen will often cause it to respond by a sexual crouch, especially if it is low in social rank.
Learning ability
  • Hens soon learn to pull, tug, peck and scratch, and their general natural activity means they will work at tasks for quite long periods.
  • Hens have limited ability to generalise, i.e. they stick to the task in hand and don't drift off target.
  • They are good at visual discrimination tasks.
  • Their limited flexibility may be an advantage in intensive conditions where they will not be bored as quickly as a species like the pig that can generalise.
  • In maze tests hens ranked after man, pig, dog, goat and before rat, rabbit, cat and turtle in ability to remember.
  • In a Hebb-Williams closed-field test, hens ranked after dogs, cows, sheep, pigs, cats, rats and ferrets but better than pigeons, guinea pigs or possums.

Social behaviour

Vocal communication
  • Being a social bird from the open forest, the hen has developed a wide range of sounds for communication.
  • Studies have classified 12 chick calls and 22 calls by adults. These range from clucks, cackles, chirps and cries to keep in contact with mates.
  • Calls heard most often and recognised by humans are food calls, predator alarms, pre- and post-laying calls and roosters crowing. Others are more specific which humans find hard to identify.
  • Another classification describes these:
  • Vocal calls related to fear and predators
  • Physiological calls to do with brooding, feeding, contact and pleasure
  • Signals expressing pain, frustration, fighting and crowing.
  • There's a well-recognised daily pattern of crowing near dawn followed by feeding calls, egg-laying calls and finally roosting calls. Chicken distress calls immediately get the attention of their broody mother, and the regular "cluck -cluck" is a reassuring call from the mother to the chicks.
  • Large groups of hens can create very high noise levels. They are around 72-87dB at normal times, 73-100 dB at feeding and 75-85 dB during egg laying.
  • A study showed that laying hens were affected by levels above 83dB, while higher levels induced fear and panic.
Body posture
  • When hens can see each other, they communicate by body postures e.g. head up or down, tail up or down, feathers spread or not.
  • The tail is especially important and studies of feral birds showed that they stood upright with tail erect with wings diamond-pointed almost vertically down. This is called "wing-down alert".
  • Body postures are particularly important to dominant males to send messages to his harem and possible competitors for his job.
  • Individual recognition.Studies have shown that birds recognise each other using a combination of comb, head and wattle. Single elements were more difficult for hens to recognise, but the comb was the simplest.
  • Colour changes to plumage were noticed, with intense colours more easily seen than pale colours.
  • Only abrupt and very dramatic changes cause a hen to be treated as a stranger.

Pecking and peck order
  • Pecking is very much a species-specific behaviour of hens. Hens peck to:
  • Release them from the shell.
  • To find feed and eat it.
  • To drink.
  • To obtain space.
  • To get recognition from others.
  • To mate.
  • And many more highly sophisticated actions.
  • Hens maintain a personal space around their heads and keep a distance from each other by holding their heads at an angle and maintaining a specific body orientation.
  • If a direct head-to-head stance is taken, then pecking will ensue.
  • The main purpose of pecking is in eating and it's a very precisely tuned movement of the head and neck, the feed being first picked up and then in a further movement of the head, it is swallowed.
  • Incorrect timing of these movements would severely jar the neck. The bird's binocular vision is important in judging the distance to peck with the eye membranes closed at the moment of impact.
  • The relationship of body stance and head position is important during pecking attacks. These include threats in which one bird lifts its head above the level of the other bird's head, then pecks the comb, head, neck or nape, wattles and then chases the subordinate away.
  • If two birds face up to each other to fight, they peck, kick with their feet and slash with their spurs. Crouching or running away shows submission. These fights are not common outdoors but they increase as stocking rates increase towards 400 square cm/bird.
  • In free-living birds, pecking is greatly reduced when males are present, as presumably the peck order is more clearly established.
  • Pecking is often greatest in adolescent hens and observations have shown the incidence to be 30-50% greater on floors than in cages. Pecking was 70% higher when males were absent.
  • Practical suggestions to help stabilise a peck order quickly to avoid any negative impact on egg production are:
  • Form new groups of hens by mixing them before they start laying.
  • Do not revolve birds around groups - leave them settled.
  • Provide plenty of feed and watering points and plenty of floor space when the flock is settling.
  • If two groups have to be mixed, put equal numbers of each subgroup together.
  • Make sure males have been together in a group before mixing with the hens.
  • Putting a male among hens will reduce pecking.
  • Much of the pecking in caged birds occurs during feeding bouts, and depends on the feeder space and number of birds in the cage.
Dust bathing
  • Hens love to dust bath, and it is clearly an innate behaviour.
  • Dust bathing behaviour actions are even seen by birds bred with no feathers.
  • We assume that hens dust bathe to control parasites and align their feathers. Normally free-living hens spend their time dispersed except when it comes to dust bathing, which they seem to love to do communally.
  • Dust bathing is also thought to be a type of vacuum activity seen in birds that have been released from cages after at least 100 hours without a bath, or in birds with previous experience of the practice.
  • Dust bathing usually starts with pecking into an area of dry dust, squatting in it, turning and raising dust into the feathers and then shaking it out again.
Preening and feather care
  • In preening, the hen raises the feathers and cleans them by stroking and nibbling them with the beak.
  • Grooming in the hen is described as actions related to maintaining body surface including preening with the beak, scratching with the foot, dust bathing and oiling.
  • Oil is produced from the urophygial gland near the tail and birds use their beak to spread oil from it over their feathers.
  • Hens preen or groom to remove lice, and females are more efficient groomers than males.
  • Hens also spend more time grooming and using their oil gland than cocks.
Other comfort behaviours
  • Bill wiping is seen after birds have been eating wet mash.
  • The bird wipes one side of the beak on the ground, and in one continuous movement wipes the other side.
  • Unilateral stretching of the leg and wing is also common comfort behaviour along with wing flapping while standing still.
Roosting or perching
  • The feet of a bird are designed for holding on to branches while resting and roosting.
  • The wild jungle fowl roosts up off the ground in a communal roost in the centre of its territory.
  • Wild birds will also perch at different levels.
  • Depriving birds of these behaviours is one of the main concerns with modern poultry husbandry.

This material is provided in good faith for information purposes only, and the author does not accept any liability to any person for actions taken as a result of the information or advice (or the use of such information or advice) provided in these pages.

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