Sham dustbathing

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Sham dustbathing is a behaviour performed by some birds when kept in cages with little or no access to litter, during which the birds perform all the elements of normal dustbathing, but in the complete absence of any substrate. [1] [2] [3] This behaviour often has all the activities and temporal patterns of normal dustbathing, i.e. the bird initially scratches and bill-rakes at the ground, then erects its feathers and squats. Once lying down, the behaviour contains four main elements: vertical wing-shaking, head rubbing, bill-raking and scratching with one leg. Normal dustbathing is a maintenance behaviour whose performance results in dust collecting between the feathers. The dust is then subsequently shaken off which reduces the amount of feather lipids and so helps the plumage maintain good insulating capacity and may help control of ectoparasites. [4]

Contents

Terminology

Sham dustbathing is sometimes referred to as "vacuum dustbathing". In the Konrad Lorenz model of behaviour regulation, vacuum activities occur when motivation for a certain behaviour builds to a sufficiently high level that the behaviour is performed in the complete absence of relevant stimuli. However, hens "dustbathing" on wire floors commonly perform this close to the feed trough where they can peck and bill-rake in the food. [5] Because it seems the birds appear to treat the feed as a dustbathing substrate, the term "sham dustbathing" is more appropriate.

Motivational basis

A hen performing normal dustbathing Hen dustbathing.jpg
A hen performing normal dustbathing

Sham dustbathing, like normal dustbathing, appears to have both internal and external causal factors.

Internal causal factors

Under unrestricted conditions, adult birds dustbathe about every second day, with a diurnal rhythm peaking in the middle of the day, and an average dustbathing bout lasting about 27 minutes. Hens without litter (i.e. an absence of external causal factors) will perform sham dustbathing with a similar temporal pattern. Some hens deprived of litter until they had developed sham dustbathing and then given access to litter, showed sham dustbathing although litter was available. Thus, there is some support for an effect of habit or early experience on sham dustbathing. [1]

Depriving hens of the opportunity to dustbathe results in a rebound when hens are again allowed access to dust. Birds work for access to litter, [6] in which case they sometimes, although not always, dustbathe. There are indications of stress when hens are deprived of the possibility to dustbathe, and if this deprivation is sufficiently long, sham dustbathing behaviour develops.

External causal factors

It has been suggested that the sight of other hens performing the behaviour increases for sham dustbathing, i.e. social facilitation, however, when tested the sight of stimulus birds had no effect on the sham dustbathing behaviour of test birds. [1] As indicated above, hens "dustbathing" on wire floors commonly perform this close to the feed trough where they can peck and bill-rake in the food, [5] indicating this may be an external causal factor.

Welfare

Sham dustbathing raises an interesting question in animal behaviour, motivation and welfare. Hens that have been reared in captivity without ever having encountered litter will perform sham dustbathing. [6] Therefore, it can be questioned how these birds, which have never had the possibility to dustbathe in a functional substrate, perceive sham dustbathing; do they yearn for something that they have never had or known (i.e. litter), or are they content to sham dustbathe? A weighted push-door was used as the operant method to quantify motivation to dustbathe in adult hens with different previous experiences of litter. There was no difference between hens in the weight of doors they pushed open to gain access to peat. Hens that had no previous experience of peat were as motivated to work to gain access to this substrate as birds used to dustbathing in peat. This implies that sham dustbathing is not satisfying to the hen nor is it perceived as normal dustbathing.

See also

Related Research Articles

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Debeaking is the partial removal of the beak of poultry, especially layer hens and turkeys although it may also be performed on quail and ducks. Most commonly, the beak is shortened permanently, although regrowth can occur. The trimmed lower beak is somewhat longer than the upper beak.

An ethogram is a catalogue or inventory of behaviours or actions exhibited by an animal used in ethology.

Battery cages are a housing system used for various animal production methods, but primarily for egg-laying hens. The name arises from the arrangement of rows and columns of identical cages connected together, in a unit, as in an artillery battery. Although the term is usually applied to poultry farming, similar cage systems are used for other animals. Battery cages have generated controversy between advocates for animal rights and industrial producers.

Displacement activity

Displacement activities occur when an animal experiences high motivation for two or more conflicting behaviours: the resulting displacement activity is usually unrelated to the competing motivations. Birds, for example, may peck at grass when uncertain whether to attack or flee from an opponent; similarly, a human may scratch their head when they do not know which of two options to choose. Displacement activities may also occur when animals are prevented from performing a single behaviour for which they are highly motivated. Displacement activities often involve actions which bring comfort to the animal such as scratching, preening, drinking or feeding.

Poultry farming Part of animal husbandry

Poultry farming is the form of animal husbandry which raises domesticated birds such as chickens, ducks, turkeys and geese to produce meat or eggs for food. Poultry – mostly chickens – are farmed in great numbers. More than 60 billion chickens are killed for consumption annually. Chickens raised for eggs are known as layers, while chickens raised for meat are called broilers.

Vacuum activities are innate, fixed action patterns (FAPs) of animal behaviour that are performed in the absence of a sign stimulus (releaser) that normally elicit them. This type of abnormal behaviour shows that a key stimulus is not always needed to produce an activity. Vacuum activities often take place when an animal is placed in captivity and is subjected to a lack of stimuli that would normally cause a FAP.

Dust bathing

Dust bathing is an animal behavior characterized by rolling or moving around in dust, dry earth or sand, with the likely purpose of removing parasites from fur, feathers or skin. Dust bathing is a maintenance behavior performed by a wide range of mammalian and avian species. For some animals, dust baths are necessary to maintain healthy feathers, skin, or fur, similar to bathing in water or wallowing in mud. In some mammals, dust bathing may be a way of transmitting chemical signals to the ground which marks an individual's territory.

Feather pecking

Feather pecking is a behavioural problem that occurs most frequently amongst domestic hens reared for egg production, although it does occur in other poultry such as pheasants, turkeys, ducks, broiler chickens and is sometimes seen in farmed ostriches. Feather pecking occurs when one bird repeatedly pecks at the feathers of another. The levels of severity may be recognized as mild and severe. Gentle feather pecking is considered to be a normal investigatory behaviour where the feathers of the recipient are hardly disturbed and therefore does not represent a problem. In severe feather pecking, however, the feathers of the recipient are grasped, pulled at and sometimes removed. This is painful for the receiving bird and can lead to trauma of the skin or bleeding, which in turn can lead to cannibalism and death.

Abnormal behaviour of birds in captivity

Abnormal behavior of birds in captivity has been found to occur among both domesticated and wild birds. Abnormal behavior can be defined in several ways. Statistically, 'abnormal' is when the occurrence, frequency or intensity of a behaviour varies statistically significantly, either more or less, from the normal value. This means that theoretically, almost any behaviour could become 'abnormal' in an individual. Less formally, 'abnormal' includes any activity judged to be outside the normal behaviour pattern for captive birds of that particular class or age. For example, running rather than flying may be a normal behaviour and regularly observed in one species, however, in another species it might be normal but becomes 'abnormal' if it reaches a high frequency, or in another species it is rarely observed and any incidence is considered 'abnormal'. This article does not include 'one-off' behaviours performed by individual birds that might be considered abnormal for that individual, unless these are performed repeatedly by other individuals in the species and are recognised as part of the ethogram of that species.

Vent pecking is an abnormal behaviour of birds performed primarily by commercial egg-laying hens. It is characterised by pecking damage to the cloaca, the surrounding skin and underlying tissue. Vent pecking frequently occurs immediately after an egg has been laid when the cloaca often remains partly everted exposing the mucosa, red from the physical trauma of oviposition or bleeding if the tissue is torn by her laying an egg. Vent pecking clearly causes pain and distress to the bird being pecked. Tearing of the skin increases susceptibility to disease and may lead to cannibalism, with possible evisceration of the pecked bird and ultimately, death.

Animal welfare science is the scientific study of the welfare of animals as pets, in zoos, laboratories, on farms and in the wild. Although animal welfare has been of great concern for many thousands of years in religion and culture, the investigation of animal welfare using rigorous scientific methods is a relatively recent development. The world's first Professor of Animal Welfare Science, Donald Broom, was appointed by Cambridge University (UK) in 1986.

Cannibalism in poultry

Cannibalism in poultry is the act of one individual of a poultry species consuming all or part of another individual of the same species as food. It commonly occurs in flocks of domestic hens reared for egg production, although it can also occur in domestic turkeys, pheasants and other poultry species. Poultry create a social order of dominance known as pecking order. When pressure occur within the flock, pecking can increase in aggression and escalate to cannibalism. Cannibalism can occur as a consequence of feather pecking which has caused denuded areas and bleeding on a bird's skin. Cannibalism can cause large mortality rates within the flock and large decreases in production due to the stress it causes. Vent pecking, sometimes called 'cloacal cannibalism', is considered to be a separate form of cannibalistic pecking as this occurs in well-feathered birds and only the cloaca is targeted. There are several causes that can lead to cannibalism such as: light and overheating, crowd size, nutrition, injury/death, genetics and learned behaviour. Research has been conducted to attempt to understand why poultry engage in this behaviour, as it is not totally understood. There are known methods of control to reduce cannibalism such as crowd size control, beak trimming, light manipulation, perches, selective genetics and eyewear.

Furnished cages, sometimes called enriched or modifiedcages, are cages for egg laying hens which have been designed to overcome some of the welfare concerns of battery cages whilst retaining their economic and husbandry advantages, and also provide some of the welfare advantages of non-cage systems. Many design features of furnished cages have been incorporated because research in animal welfare science has shown them to be of benefit to the hens.

Blinders (poultry) devices fitted to, or through, the beaks of poultry to block their forward vision

Blinders, also known as peepers, are devices fitted to, or through, the beaks of poultry to block their forward vision and assist in the control of feather pecking, cannibalism and sometimes egg-eating. A patent for the devices was filed as early as 1935. They are used primarily for game birds, pheasant and quail, but also for turkeys and laying hens. Blinders are opaque and prevent forward vision, unlike similar devices called spectacles which have transparent lenses. Blinders work by reducing the accuracy of pecking at the feathers or body of another bird, rather than spectacles which have coloured lenses and allow the bird to see forwards but alter the perceived colour, particularly of blood. Blinders are held in position with a circlip arrangement or lugs into the nares of the bird, or a pin which pierces through the nasal septum. They can be made of metal (aluminium), neoprene or plastic, and are often brightly coloured making it easy to identify birds which have lost the device. Some versions have a hole in the centre of each of the blinders, thereby allowing restricted forward vision.

Preference test

A preference test is an experiment in which animals are allowed free access to multiple environments which differ in one or more ways. Various aspects of the animal's behaviour can be measured with respect to the alternative environments, such as latency and frequency of entry, duration of time spent, range of activities observed, or relative consumption of a goal object in the environment. These measures can be recorded either by the experimenter or by motion detecting software. Strength of preference can be inferred by the magnitude of the difference in the response, but see "Advantages and disadvantages" below. Statistical testing is used to determine whether observed differences in such measures support the conclusion that preference or aversion has occurred. Prior to testing, the animals are usually given the opportunity to explore the environments to habituate and reduce the effects of novelty.

Consumer demand tests (animals)

Consumer demand tests for animals are studies designed to measure the relative strength of an animal's motivation to obtain resources such as different food items. The test results are analogous to human patterns of purchasing resources with a limited income. For humans, the cost of resources is usually measured in money; in animal studies the cost is usually represented by energy required, time taken or a risk of injury. Costs of resources can be imposed on animals by an operant task, a natural aversion, or a homeostatic challenge. Humans usually decrease the amount of an item purchased as the cost of that item increases. Similarly, animals tend to consume less of an item as the cost of that item increases . Such demand tests quantify the strength of motivation animals have for resources whilst avoiding anthropomorphism and anthropocentrism.

Comfort behaviour in animals

Comfort behaviours in animals are activities that help maintain the pelage, feathers, integuement or musculoskeletal system and increase the physical comfort of the animal.

Social facilitation in animals

Social facilitation in animals is when the performance of a behaviour by an animal increases the probability of other animals also engaging in that behaviour or increasing the intensity of the behaviour. More technically, it is said to occur when the performance of an instinctive pattern of behaviour by an individual acts as a releaser for the same behaviour in others, and so initiates the same line of action in the whole group. It has been phrased as "The energizing of dominant behaviors by the presence of others."

Chris Sherwin English veterinary scientist

Christopher M. Sherwin was an English veterinary scientist and senior research fellow at the University of Bristol Veterinary School in Lower Langford, Somerset. He specialised in applied ethology, the study of the behaviour of animals in the context of their interactions with humans, and of how to balance the animals' needs with the demands placed on them by humans.

References

  1. 1 2 3 Olsson, I.A.S., Keeling L.J. and Duncan, I.J.H., 2002. Why do hens sham dustbathe when they have litter? Applied Animal Behaviour Science, 76: 53–64
  2. Merrill, R.J.N., Cooper, J.J., Albentosa M.J. and Nicol, C.J., 2006. The preferences of laying hens for perforated Astroturf over conventional wire as a dustbathing substrate in furnished cages. Animal Welfare, 15:173–178
  3. van Liere, D.W., 1992. The significance of fowls' bathing in dust. Animal Welfare, 1:187–202
  4. Olsson, I.A.S. and Keeling, L.J., 2005. Why in earth? Dustbathing behaviour in jungle and domestic fowl reviewed from a Tinbergian and animal welfare perspective. Applied Animal Behaviour Science, 93: 259-282
  5. 1 2 Lindberg, A.C. and Nicol, C.J. 1997. Dustbathing in modified battery cages: is sham dustbathing an adequate substitute? Applied Animal Behaviour Science, 55: 113–128
  6. 1 2 Wichman, A. & Keeling, L.J., 2008. Hens are motivated to dustbathe in peat irrespective of being reared with or without a suitable dustbathing substrate. Animal Behaviour, 75: 1525-1533