Nowak, R., Porter, R. H., Blache, D. et al. 2008. Behavior and welfare of the sheep. In: The Welfare of Sheep. Dwyer, C. M. (ed). Springer, New York, NY.

The most important features of the behaviour of sheep are their marked sociality and the bond formation between mother and young. Sheep show a strong need to stay with their group (or subgroup for some breeds), and become very vocal and agitated when separated from their flock mates. Social life requires rules that maintain the stability of the group and increase the fitness of each individual. Under wild or feral conditions, sheep populations contain a wide range of individuals including sexually mature females, juvenile males and females, and lambs, and their composition fluctuates over time. Adult males usually join a flock of females during the mating season. Under domestic conditions humans mainly control the social environment, and animals are usually maintained in single-sex groups of similar age or size, the main exceptions being the mother-young dyad, and male-female groups at mating. Social dominance is not as obvious as in other ruminants, unless the animals are confined and have to compete for resources. Sheep can nonetheless recognise other individuals of the group using various sensory modalities and this necessarily plays a role in group cohesion and bonding. From an animal welfare point of view, the important aspects of sheep behaviour are those related to social stability, abnormal forms of behaviour, and survival of the young. In general, mixing groups of sheep does not lead to increased agonistic behaviour between individuals and therefore social instability has never been a major concern. Separating mother and young is common practice even at an early age, especially in dairy breeds. Despite the existence of a strong affectional bond between the ewe and her lamb, a clear demonstration of behavioural deficits in lambs reared with peers, but without their dam, has never been reported. Early experience can, however, affect later sexual behaviour. Stereotyped behaviours, which are commonly used as an index of poor welfare, are rare in sheep compared to other species. Behavioural research has enormously advanced our understanding of the requirements of ewes and lambs at parturition, and the nature of the social bond that forms at birth. This has provided advances towards practical solutions to reduce lamb mortality. The issues associated with intensive farming relate to confinement and social restriction in pens, but there is a need for further investigation. Animal-human relationships may also be important, especially for intensively farmed sheep that have more contact with humans than do sheep under extensive conditions.