The progenitors of the domestic chickens - the red jungle fowl of southeast Asia - are social birds who prefer habitats with dense vegetation that provides good cover. Neither thousands of years of domestication nor the recent extreme selective breeding for productivity have significantly altered the biological and behavioral characteristics of these birds (Fölsch and Vestergaard, 1981; Rogers, 1995). This has to be kept in mind when suitable housing for chickens is designed.
The different behaviors shown by chickens can be categorized as follows:
|Figure 2. Comfortable laying nests are a "must" for any chicken quarters (Photo by Viktor Reinhardt).|
Whether chickens are kept in rooms or in so-called enriched cages, the following provisions must be made to address the animals' basic species-specific needs: social housing, laying nest, elevated perch(es), natural light, area(s) for pecking, scratching and sand bathing (Figures 2-5).
A chicken should never be kept alone. Separation from conspecifics is a distressing experience (Rajecki et al., 1977) that is bound to have an influence on research data collected. The occurrence of feather-, foot- and claw damage is less in cages equipped with a nest box, a perch and an area for pecking/scratching/bathing, indicating that these items significantly improve the welfare of chickens (Appleby et al., 1993). As far as the hens' immediate response to their environment is concerned, space per se is not the only relevant factor. Just as, if not more, important are the structuring of the vertical dimension and the quality of the flooring. Hens will voluntarily "work" for access to litter, indicating that a litter substrate is highly valued by them (Matthews et al., 1994; Widowski and Duncan, 2000). Chickens should always have access to a sufficiently spacious litter area where they can move around without experiencing the discomfort associated with wire floors. Not surprisingly, chickens show a clear preference for litter over wire floors (Hughes, 1976). Hens with access to litter in an otherwise barren environment spent around 18% of their time in litter-related activities (Hughes and Channing, 1998).
A room may be readily transformed to suitable housing for chickens by placing a wire-mesh covered dropping pit on one side of the room and installing perches along the wall at different heights over the pit. The horizontal distance between two perches should be at least 35 cm (Figure 3). Chickens prefer roosts that are large [5 cm diameter] rather than small, and square or round rather than triangular in shape (Muiruri et al., 1990). The total perch-length is determined by the number of chickens and should be no less than 18 cm per animal. Chickens kept in unstructured enclosures will use locations near walls more than expected and avoid the empty central area (Newberry and Hall, 1990). The provision of different horizontal levels (Fölsch et al., 1988) or vertical panels can ameliorate this problem. Such structures facilitate a more uniform distribution of the birds, thereby increasing their useable floor space (Cornetto and Estevez, 2001) and, probably, also enhancing their well-being (Newberry and Shackleton, 1997).
|Figure 3. For resting, sleeping and withdrawal, chickens prefer elevated places, natural trees and bushes. This is why the provision of perches is an imperative for any housing system of chickens.|
A scratching area is an imperative to allow chickens to exhibit species-typical foraging behavior. Similar to other laboratory animals, the foraging drive is so strong in chickens that they will "work" for food in the presence of freely accessible identical food (Duncan and Hughes, 1972). This suggests that foraging is a rewarding activity in itself independent of caloric intake (Neuringer, 1969). A thin layer of sand covered by approximately 10 cm of chopped straw provides a suitable substratum onto which the grain can be scattered thus triggering prolonged foraging. This scratching/foraging area should take up at least half of the horizontal floor space of the enclosure.
|Figure 4. Chicks and young hens should get perches early in life so that they learn perching and use the third dimension.|
Hens need adequate nest boxes, preferably with manipulable material, like oat husks or chopped straw (Figure 2). One nest box per 5 hens should be provided. Its dimensions should be approximately 40 x 40 cm. If larger family nests are used, a nesting area of 1 m2 per 50 hens is recommended.
It is said that group size should not exceed 80 animals, as chickens are only able to distinguish between 40 to 80 members of their own species. Nevertheless, there is evidence that hens kept in aviary units of 2,200 establish a social organization (Keppler et al., 1997). Stocking density should not exceed 5 birds per square meter of available surface area to avoid stress from overcrowding.
As with other laboratory animals, the presence of a social companion has a stress buffering effect in chickens (Jones and Merry, 1988). In order to avoid data-biasing stress responses, it is therefore advisable to allow individual chicks or hens to maintain visual and acoustic contact with at least one familiar conspecific during experimental procedures.
A variety of food should be offered to the chickens. If only meal or pellets are fed, the animals consume their ration too fast and do not spend enough time foraging. Feather pecking can easily develop under such conditions. To prevent this, grain should be thrown onto the litter to promote scratching and pecking behaviors. Fruit, grass, straw and hay should be provided in racks or in baskets hanging from the ceiling, so that the animals can pull and peck at the contents rather than at each other. Rearing chicks with access to sand, peat or straw as litter substrates for dustbathing, pecking and foraging reduces later tendencies to engage in feather pecking (Nørgaard-Nielsen et al., 1993; Huber-Eicher and Wechsler, 1997; Nicol et al., 2001). It is, therefore, advisable to offer chicks access to litter from day one on (Huber-Eicher and Sebö, 2001). If straw is provided as litter substrate, special attention should be paid to its form, as long-cut straw is more efficient in reducing feather pecking than straw in shredded form (Wechsler and Huber-Eicher, 1998).
Feeding space should be 5 cm per bird on circular feeders and 12 cm per bird on feeding belts. There should be one watercup or one nipple drinker per 8 birds and a watertrough length of 2-3 cm per bird, respectively. Chickens can drink much better from open receptacles than from nipple drinkers. It is therefore recommended to provide water in troughs or cups rather than forcing the birds to drink from nipple drinkers.
Chickens should have access to a box filled with sand so that they can take dust-baths. Dustbathing is a social activity that is usually performed by several birds at the same time (Figure 5). The sand box has to be relatively spacious, i.e., 80 x 80 cm per 50 birds.
A dustbath is used for care and cleaning of plumage and|
enhances well-being. Chickens prefer to dustbathe in groups. If
the dustbath is provided outside, it should be roofed and should give
protection from drafts. Quartz sand with charcoal and flowers of
sulphur is recommended as a dustbathing substrate.
A bad-weather run should be provided so that the chickens have exposure to natural daylight and seasonal temperature variations throughout the year. The run should have a roof so that the birds have access to the sheltered area even in bad weather. Wire-mesh walls or a meshed plastic netting will protect the animals from predators. The sheltered run should be about half the size of the hen house and have a concrete floor covered with a layer of straw and sand (Figure 6-7).
|Figure 7. A bad-weather run should be provided so that the chickens have exposure to natural daylight and seasonal temperature variations throughout the year.|
Chickens clearly prefer an outside run to a cage, once initial unfamiliarity with the run has been overcome (Dawkins, 1977). An outdoor run is, therefore, highly recommended. It should be covered to protect the animals from prey birds or provisioned with bushes and trees so that the animals have places where they can take cover (Figure 8). The addition of organic material or a compost heap gives the chickens optimal opportunities to perform a wide array of species-specific behaviors. The stocking density in the outdoor run may be up to 10 hens/m2 if pastures are used alternately. It should be no more than 2 hens/m2 if no rotation of pastures is possible. Animals who spend more than half of their time outside are less fearful, and the time of tonic immobility is shorter compared with animals who have no access to an outdoor run (Grigor et al., 1995). Also, hens who have been kept in free-range systems show less fear reactions after being transported than hens who have been kept in cages (Scott et al., 1998). These findings indicate keeping chickens in free range systems fosters their capability to adapt to potentially stressful situations.
|Figure 8. An outside run is highly recommended. It should have bushes and trees for cover.|
A cage is not an appropriate housing environment for chickens. The birds demonstrate this by exhibiting more pronounced fear responses when kept in cages versus floor pens (Jones and Faure, 1981a). It should be emphasized again that any cage for chickens has to be equipped at a minimum with a laying nest, a high perch, and an area for pecking, scratching and dustbathing to meet fundamental behavioral needs of the animals (Figure 9).
| Hen cage
for laboratory purposes|
Globogal AG, CH-5600 Lenzburg (Switzerland)
Figure 9. Plan view [left drawing] and cross
section [right drawing] of a cage design addressing the minimum behavioral needs
of the chickens kept in research institutions. Note that provision is made for a
nestbox, a scratching area, perches and a water receptacle.
If chickens are kept in cages in a research institution [e.g., for metabolic studies], the cages should not be arranged in multiple tiers in order to avoid data-confounding variables resulting from different degrees of fear responses in birds kept at different levels of the room (Sefton, 1976; Jones, 1985; Hemsworth et al., 1993) and different illumination in cages at different distances from the light source.
The greatest risk of physical injury will occur if chickens become frightened and attempt to escape from their cages, either during catching procedures or simply when disturbed by human presence. It is, therefore, important to allow sufficient space for running and wing flapping to maintain good bone strength (Whitehead et al., 1997/98). This freedom must be coupled with the provision of a small, safe catching area. The birds can often be enticed into such areas if these are well lit while the rest of the room is temporarily darkened (Nicol, 1995).
Chickens are highly susceptible to stress
when they are caught and handled. Regular gentle interactions with chickens
reduces fear and facilitates easier, i.e., less stressful handling during
procedures (Hughes and Black, 1976; Jones and Faure, 1981b; Gross and Siegel,
1982; Jones, 1994; Figure 10). The stress response can further be minimized by
performing any procedures during dim-lighting conditions. At dusk, dawn, or when
lights are turned off, chickens can normally be picked up from the floor or from
perches without causing undue commotion. A chicken should always be carried by
holding both legs while supporting the body with the hands. Gently tucking the
head under the arm helps to keep the animal calm.
|Figure 10. Regular, friendly contact with people allows chickens to overcome their instinctive fear of the human predator. Tame chickens are more reliable research models because they show little or no stress responses during handling procedures (Photo by Annie Reinhardt).|
Appleby MC, Smith SF, Hughes BO 1993. Nesting, dust bathing and perching by laying hens in cages: Effects of design on behaviour and welfare. British Poultry Science 34, 835-847
Blokhuis HJ 1984. Rest in poultry. Applied Animal Behaviour Science 12, 289-303
Blokhuis HJ, Arkes JG 1984. Some observations on the development of feather pecking in poultry. Applied Animal Behaviour Science 12, 145-157
Brake J 1987. Influence of presence of perches during rearing on incidence of floor laying in broiler breeders. Poultry Science 66, 1587-1589
Cornetto TL, Estevez I 2001. Influence of vertical panels on use of space by domestic fowl. Applied Animal Behaviour Science 71, 141-153
Dawkins M 1977. Do hens suffer in battery cages? Environmental preferences and welfare. Animal Behaviour 25, 1034-1046
Duncan IJH, Hughes BO 1972. Free and operant feeding in domestic fowls. Animal Behaviour 20, 775-777
Fölsch DW, Vestergaard K 1981. The Behaviour of Fowl - The Normal Behaviour and the Effect of Different Housing Systems and Rearing Methods - Animal Management Volume 12 Birkäuser, Basel, Switzerland
Fölsch DW, Huber H-U, Bölter U, Gozzoli I 1988. Research on alternatives to the battery systems for laying hens. Applied Animal Behaviour Science 20, 29-45
Gentle MJ, Waddington D, Hunter LN, Jones B 1990. Behavioural evidence for persistent pain following partial beak amputation in chicken. Applied Animal Behaviour Science 27, 149-157
Grigor PN, Hughes BO, Appleby MC 1995. Effects of regular handling and exposure to an outside area on subsequent fearfulness and dispersal in domestic hens. Applied Animal Behaviour Science 44, 47-55
Gross WB, Siegel PB 1982. Socialization as a factor in resistance to infection, feed efficiency, and response to antigen in chickens. American Journal of Veterinary Research 43, 2010-2012
Gunnarsson S, Matthews LR, Foster TM, Temple W 2000. The demand for straw and feathers as litter substrates by laying hens. Applied Animal Behaviour Science 65, 321-330
Hemsworth PH, Barnett JL, Jones RB 1993. Situational factors that influence the level of fear of human by laying hens. Applied Animal Behaviour Science 36, 197-210
Huber H-U, Fölsch DW, Stähli U 1985. Influence of various nesting materials on nest site selection of the domestic hen. British Poultry Science 26, 367-373
Huber-Eicher B, Wechsler B 1997. Feather pecking domestic chicks: Its relation to dustbathing and foraging. Animal Behaviour 54, 757-768
Huber-Eicher B, Sebö F 2001. Reducing feather pecking when raising laying hen chicks in aviary systems. Applied Animal Behaviour Science 73, 59-68
Hughes BO 1976. Preference decisions of domestic hens for wire or litter floors. Applied Animal Ethology [Applied Animal Behaviour Science] 2, 155-165
Hughes BO, Black AJ 1976. The influence of handling on egg production, egg shell quality and avoidance behaviour of hens. British Poultry Science 17, 135-144
Hughes BO, Channing CE 1998. Effects of restricting access to litter trays on their use by caged laying hens. Applied Animal Behaviour Science 56, 37-45
Jones RB 1982. Effects of early environmental enrichment upon open-field behavior and timidity in the domestic chick. Developmental Psychobiology 15, 105-111
Jones RB 1985. Fear responses of individually-caged laying hens as a function of cage level and aisle. Applied Animal Behaviour Science 14, 63-75
Jones RB 1994. Regular handling and the domestic chick's fear of human beings: generalisation of response. Applied Animal Behaviour Science 42, 129-143
Jones RB, Faure JM 1981a. Tonic immobility ("righting time") in laying hens housed in cages and pens. Applied Animal Ethology 7, 369-372
Jones RB, Faure JM 1981b. The effects of regular handling on fear responses in the domestic chick. Behavioural Processes 6, 135-143
Jones RB, Merry BJ 1988. Individual or paired exposure of domestic chicks to an open field: some behavioural and adrenocortical consequences. Behavioural Processes 16, 75-86
Keppler C, Schnurrenberger-Bölter U, Fölsch DW 1997. Activity and social relationships of chickens (Gallus gallus f. domesticus) in aviary systems - methods and preliminary results. In 5th Symposium on Poultry Welfare Koene P, Blockhuis, HJ (eds), 105-106. World´s Poultry Science Association, University of Wageningen, Netherlands
Keppler C, Fölsch DW 2000. Locomotive behaviour of hens and cocks (Gallus gallus f. domesticus): Implications for housing systems. Archiv für Tierzucht 43, 184-188
Matthews LR, Temple W, Foster TM, McAdie TM 1994. Quantifying the environmental requirements of layer hens by behavioural demand functions. Applied Animal Behaviour Science 40, 91
Muiruri HK, Harrison PC, Gonyou HW 1990. Preferences of hens for shape and size of roosts. Applied Animal Behaviour Science 27, 141-147
Neuringer AJ 1969. Animals respond for food in the presence of free food. Science 166, 399-401
Newberry RC, Hall JW 1990. Use of pen space by broiler chickens: effects of age and pen size. Applied Animal Behaviour Science 25, 125-136
Newberry RC, Shackleton DM 1997. Use of visual cover by domestic fowl: a Venetian blind effect? Animal Behaviour 54, 387-395
Nicol CJ 1995. Environmental enrichment for birds. AWIC Resource Series No. 2 - Environmental Enrichment Information Resources for Laboratory Animals 1995-1995, Birds, Cats, Dogs, Farm Animals, Ferrets, Rabbits, and Rodents, 1-3
Nicol CJ, Lindberg AC, Phillips AJ, Pope SJ, Wilkins LJ, Green LE 2001. Influence of prior exposure to wood shavings on feather pecking, dustbathing and foraging in adult laying hens. Applied Animal Behaviour Science 73, 141-155
Nørgaar-Nielsen G, Vestergaard K, Simonsen HB 1993. Effects of rearing experience and stimulus enrichment on feather damage in laying hens. Applied Animal Behaviour Science 38, 345-352
Rajecki DW, Suomi SJ, Scott EA, Campbell B 1977. Effects of social isolation and social separation in domestic chicks. Developmental Psychology 13, 143-155
Rogers LJ 1995. The Development of Brain and Behaviour in the Chicken CAB International, Wallingford, UK
Scott GB, Connell BJ, Lambe NR 1998. The fear levels after transport of the hens from cages and a free-range system. Poultry Science 77, 62-66
Sefton AE 1976. The interactions of cage size, cage level, social density, fearfulness and production of Single Comb White Leghorns. Poultry Science 55, 1922-1926
van Liere DW, Bokma S 1987. Short-term feather maintenance as a function of dust-bathing in laying hens. Applied Animal Behaviour Science 18, 197-204
Wechsler B, Huber-Eicher B 1998. The effect of foraging material and perch height on feather pecking and feather damage in laying hens. Applied Animal Behaviour Science 58, 131-141
Whitehead C, Fleming B, Bishop S 1997/98. Towards a Genetic Solution to Osteoporosis in Laying Hens: Annual Report Roslin Institute, Midlothian, UK
Widowski TM, Duncan IJH 2000. Working for a dustbath: are hens increasing pleasure rather than reducing suffering? Applied Animal Behaviour Science 68, 39-53
Detlef W. Fölsch is Professor of Farm Animal Ethology and Management at the University of Kassel/Witzenhausen, Germany. His extensive research in chicken ethology and commitment to animal welfare and responsible agriculture were instrumental in the implementation of the ban on battery cages for laying hens in Switzerland in 1986. He and his co-workers were also instrumental in adoption of a German law mandating that, beginning in 2007, laying hens will have to be kept in systems other than battery cages.
Marlene Höfner is a graduate agriculturist. She investigated the effects on optimizing outside runs on the behavior of hens and on the environment at the University of Kassel/Witzenhausen, Germany.
Marion Staack is a graduate agriculturist with a Master of Science degree in Applied Animal Behavior and Animal Welfare. She has collaborated with Detlef Fölsch in the project Alternative Housing Systems for Poultry.
Gerriet Trei is a Ph.D. student with Professor Fölsch. He works on feeding behaviour, optimizing the composition of food for hens. He has collaborated with Detlef Fölsch in the projects “Alternative Housing Systems for Poultry in Hessia” and “Animal and Environmental Friendly Housing Systems for Poultry“ of the German Ministry for Consumer Protection, Food and Agriculture.
Back to Table of Contents