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The social behaviour of the fowl
84
terns occur in the artificial conditions typical of captivity. The function of social hierarchies. It is still often stated that the function of a social hierarchy is to reduce fighting and to keep peace. Such a point of view is logically weak. A hierarchy is not a structure; it is a consequence of relationships becoming predictable as individuals optimize their own agonistic strategies to maximize their fitness (Deag, 1977). It is therefore more important to look at the component relationships (including submissiveness), than to look at the gross structure of the hierarchy. If an aggression-reducing function is ascribed to a hierarchy it is tempting to assume that all is well when a hierarchy is seen. However, in captivity the reverse can be true; animals may be members of a hierarchy but stressed to an extent not seen in the wild.
REFERENCES Brown, J.L., 1975. The Evolution of Behaviour. Norton, New York. Deag, J.M., 1977. Aggression and submission in monkey societies. Anim. Behav., 465-474. Deag, J.M., 1980. Social Behaviour of Animals. Edward Arnold, London. Wilson, E.O., 1975. Sociobiology. Belknap Press, Cambridge, MA.
THE SOCIAL BEHAVIOUR
25:
OF THE FOWL
B.O. HUGHES ARC
Poultry
Research
Centre,
Roslin,
Midlothian
(Gt. Britain)
ABSTRACT
In this review the social and structural flock organisation of the feral fowl was briefly described. Groups are generally rather small and social organization is complex, for it includes individuals of widely different status and age. The situation in intensive husbandry is quite different. Groups are usually single-age and mono-caste, and the social structure tends to fall at one or the other of two extremes. Deep-litter flocks of layers or broiler chickens can number up to 10 000 or more, whereas cages normally contain 4-8 hens. These changes in group size, composition and spacing have greatly distorted what might be termed the “normal” social organization. Certain behavioural problems encountered in intensive husbandry, such as cannibalism, hysteria and high levels of flightiness, may be related to such changes. In small groups, any activity caused by a disturbing event soon dies away, due to habituation, whereas in very large groups there is a positive feedback effects, and the social disturbance engendered can sometimes spread until many thousands of individuals are involved. The processes of
85
natural selection in the fowl have not equipped it to deal with this situation. In battery cages, too, the social structure is abnormal, even though group size is much closer to that found in the natural situation. Crowding has the effect of greatly reducing agonistic interactions, partly, it is thought, by the immediate presence of a dominant individual having an inhibiting influence. In addition, birds may habituate to the point where close contact no longer stimulates an overt aggressive response. The price which has to paid for this low level of aggression may be the enhanced level of fear which is often found in caged, as opposed to penned, hens. The social organization and behaviour of intensively-housed fowls are very different from that seen in feral conditions, and are related both to group size and to social spacing. Pen and cage systems both show departures from the norm, but in different directions, suggesting it would be worthwhile investigating systems which occupy intermediate positions.
SOCIAL INTERACTIONS
AMONGST
FOSTERED
PIGLETS
I. HORRELL Department
of Psychology,
University of Hull, Hull (Gt. Britain)
ABSTRACT
It has previously been demonstrated that fostering one-week-old piglets can disrupt the regular association between individual piglets and particular teats, and retard growth during the following week (Horrell and Bennett, 1981). A detailed examination was therefore made of the behavioural events in the period immediately after fostering. Twenty-four litters of piglets, between 5 and 8 days old, were observed in batches of 4. Piglet-teat relations and the timing of suckling periods were recorded for at least 3 successive suck. lings. Two litters were then selected as experimental litters and 2 piglets exchanged between them. The other 2 litters were kept intact for the collection of control data. Observations were made for 3 hours after fostering. The whole suckling process was found to be disturbed in experimental litters; experimental sows initiated more suckling periods than did controls (8.3 suckling periods per sow per observation period in experimental litters versus 4.6 in controls), but these were frequently disrupted at an early stage and only 35% of all suckling periods reached milk let-down (compared to 93% in controls over the same period). Many sows showed aggression directed quite specifically towards fostered piglets. Many fostered piglets engaged in a behavioural syndrome involving perambulating the periphery of the pen, prolonged squealing and intermittent attempts to escape. Fostered piglets were significantly slower to reach the udder at the beginning of a suckling period and less likely to be present at milk let-down. They were also involved in a
terns occur in the artificial conditions typical of captivity. The function of social hierarchies. It is still often stated that the function of a social hierarchy is to reduce fighting and to keep peace. Such a point of view is logically weak. A hierarchy is not a structure; it is a consequence of relationships becoming predictable as individuals optimize their own agonistic strategies to maximize their fitness (Deag, 1977). It is therefore more important to look at the component relationships (including submissiveness), than to look at the gross structure of the hierarchy. If an aggression-reducing function is ascribed to a hierarchy it is tempting to assume that all is well when a hierarchy is seen. However, in captivity the reverse can be true; animals may be members of a hierarchy but stressed to an extent not seen in the wild.
REFERENCES Brown, J.L., 1975. The Evolution of Behaviour. Norton, New York. Deag, J.M., 1977. Aggression and submission in monkey societies. Anim. Behav., 465-474. Deag, J.M., 1980. Social Behaviour of Animals. Edward Arnold, London. Wilson, E.O., 1975. Sociobiology. Belknap Press, Cambridge, MA.
THE SOCIAL BEHAVIOUR
25:
OF THE FOWL
B.O. HUGHES ARC
Poultry
Research
Centre,
Roslin,
Midlothian
(Gt. Britain)
ABSTRACT
In this review the social and structural flock organisation of the feral fowl was briefly described. Groups are generally rather small and social organization is complex, for it includes individuals of widely different status and age. The situation in intensive husbandry is quite different. Groups are usually single-age and mono-caste, and the social structure tends to fall at one or the other of two extremes. Deep-litter flocks of layers or broiler chickens can number up to 10 000 or more, whereas cages normally contain 4-8 hens. These changes in group size, composition and spacing have greatly distorted what might be termed the “normal” social organization. Certain behavioural problems encountered in intensive husbandry, such as cannibalism, hysteria and high levels of flightiness, may be related to such changes. In small groups, any activity caused by a disturbing event soon dies away, due to habituation, whereas in very large groups there is a positive feedback effects, and the social disturbance engendered can sometimes spread until many thousands of individuals are involved. The processes of
85
natural selection in the fowl have not equipped it to deal with this situation. In battery cages, too, the social structure is abnormal, even though group size is much closer to that found in the natural situation. Crowding has the effect of greatly reducing agonistic interactions, partly, it is thought, by the immediate presence of a dominant individual having an inhibiting influence. In addition, birds may habituate to the point where close contact no longer stimulates an overt aggressive response. The price which has to paid for this low level of aggression may be the enhanced level of fear which is often found in caged, as opposed to penned, hens. The social organization and behaviour of intensively-housed fowls are very different from that seen in feral conditions, and are related both to group size and to social spacing. Pen and cage systems both show departures from the norm, but in different directions, suggesting it would be worthwhile investigating systems which occupy intermediate positions.
SOCIAL INTERACTIONS
AMONGST
FOSTERED
PIGLETS
I. HORRELL Department
of Psychology,
University of Hull, Hull (Gt. Britain)
ABSTRACT
It has previously been demonstrated that fostering one-week-old piglets can disrupt the regular association between individual piglets and particular teats, and retard growth during the following week (Horrell and Bennett, 1981). A detailed examination was therefore made of the behavioural events in the period immediately after fostering. Twenty-four litters of piglets, between 5 and 8 days old, were observed in batches of 4. Piglet-teat relations and the timing of suckling periods were recorded for at least 3 successive suck. lings. Two litters were then selected as experimental litters and 2 piglets exchanged between them. The other 2 litters were kept intact for the collection of control data. Observations were made for 3 hours after fostering. The whole suckling process was found to be disturbed in experimental litters; experimental sows initiated more suckling periods than did controls (8.3 suckling periods per sow per observation period in experimental litters versus 4.6 in controls), but these were frequently disrupted at an early stage and only 35% of all suckling periods reached milk let-down (compared to 93% in controls over the same period). Many sows showed aggression directed quite specifically towards fostered piglets. Many fostered piglets engaged in a behavioural syndrome involving perambulating the periphery of the pen, prolonged squealing and intermittent attempts to escape. Fostered piglets were significantly slower to reach the udder at the beginning of a suckling period and less likely to be present at milk let-down. They were also involved in a