Comfortable Quarters for Chickens in Research Institutions

Detlef W. Fölsch, Marlene Höfner, Marion Staack and Gerriet Trei

University of Kassel, Faculty of Agriculture
International Rural Development and Environmental Protection
Department of Animal Behavior and Management, Nordbahnhofstraße 1a
D-37213 Witzenhausen, Germany

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 1. Chickens spend 35 to 50% of the day scratching and pecking for food.

 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.

Figure 5. 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).


1. Water
2. Used air
3. Fresh air
4. Family nest
5. Food trough
6.  Nipple drinker
7.  Litter
8.  Perches
9.  Dropping pit
10. Drainage
11. Drainpipe
12. Covered run with bas-
ket for greenstuff and extra
space gained through use
of third dimension

Figure 6. Suggestions for hen house with covered bad weather run.


 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).

 Plan View

 Cross Section


     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).


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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.

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