76. Conditions should be provided in which the birds can show those behaviours which are important to them. Systems providing an enriched and varied environment offer more scope for hens to express normal behaviour and our problem has been how to assess the significance of restrictions to this freedom experienced by birds in certain systems. We have seen evidence which suggests that nesting, foraging, dust bathing, perching and other activities are all of importance. Opportunity to express these behaviours is largely prevented in certain systems, yet it is clearly possible for hens to survive and perform well, albeit with some restriction or modification of patterns of behaviour.
77. Any definition of space allowances must include both horizontal surface area and height, both of which affect bird behaviour. The scientific literature provides relatively little information on the use of space by hens. There is a need for a clearer understanding of how hens share space and the effect of this on their individual space requirements, and for more information upon the effects of group sizes on hen behaviour and their use of space. Whenever possible, they should have space sufficient to allow them to walk from one resource to another, investigate their surroundings, flap their wings and have safe access to perches.
78. Further research, under a range of conditions which reflect practice, is required to clarify understanding of the space requirements of hens which can be translated into more precise and practical recommendations.
79. It is difficult to find clear experimental evidence to support an optimum size for groups of laying hens. Over a wide range of conditions, it appears that large group sizes may be detrimental in respect of a number of behavioural factors including: injurious feather pecking and cannibalism, fearfulness, hysteria and mortality.
80. We have reviewed the extensive evidence about normal behaviour patterns of hens when offered uninhibited opportunities. Whilst we would like to see all hens have the opportunity to exhibit the widest possible range of behaviour patterns, we find it difficult to quantify the degree of frustration or indeed suffering experienced by birds restricted by lack of space or provision of any particular facilities. The evidence suggests that the behavioural activities which are most important are nesting, perching and using litter for scratching, pecking and dust bathing.
81. Hens are strongly motivated to nest and may be frustrated if deprived of the opportunity to perform pre-nesting behaviour and to lay in a nest. It has been suggested to us that hens have difficulty in dealing with this deprivation. In the FAWC Assessment of Egg Production Systems (1986), it was stated that the "Inability to perform normal pre-laying behaviour is generally assessed as one of the most important problems for the welfare of hens in cages". In our current appraisal, scientific opinion has concurred with this statement. On the other hand, the industry suggests that battery hens can cope with the problem as evidenced by their productivity.
82. We recommend that further research be carried out to determine what a hen perceives as a nest and to define the attributes of such a nest to aid practical developments which would suit a range of systems.
83. In their natural surroundings, hens make considerable use of perches, particularly to roost at night. Hens are strongly motivated to perch and we are aware of benefits to the birds in reducing foot problems and improving bone strength. Ideally, therefore, hens should be provided with a perch. We believe that perching opportunities are important to the hen but we remain uncertain about how much frustration and suffering is caused by deprivation.
84. Where a friable litter substrate is provided, it is intensively used by hens for scratching, dust bathing and pecking. There is experimental evidence to show that hens, when given the choice, strongly prefer litter to a wire mesh floor. Hens which are deprived of litter may have a greater tendency towards injurious pecking. We are not clear how difficult it is for hens to cope without litter but ideally we feel that hens should have daily access to litter in order to dust bathe and forage.