SOCIAL FACILITATION ACTS MORE ON THE APPETITIVE THAN THE CONSUMMATORYPHASE OF FEEDING-BEHAVIOR IN DOMESTIC-FOWL

This experiment was designed to quantify the motivation to show social ly facilitated behaviour, by equating the increase in feeding behaviou r shown by a subject chicken, Gallus gallus domesticus, in response to the sight and sound of another bird feeding, with the feeding behavio ur shown by the same subject chicken following food deprivation period s of either 15, 30, 60 or 120 min. Feeding behaviour was recorded both as the amount of food consumed and the number of food pecks in a 30-m in trial period. As expected, the amount of food consumed and the numb er of food pecks following food deprivation increased linearly with le ngth of deprivation and the birds ate more during the social facilitat ion test than during the control when no stimulus bird was present. Wh en this increase in the amount of food consumed during social facilita tion was plotted on a regression line of the amount of food consumed i t was found to be equivalent to 27 min of food deprivation. When the n umber of food pecks due to social facilitation was plotted on the regr ession line of the number of food pecks it was found to be equivalent to 92 min of food deprivation. A reason for the difference between the two estimates of the motivation to feed in the social facilitation te st may be derived from the nature of the relationship between the two variables; food consumed and number of food pecks. A bird cannot eat w ithout pecking at the food, but it can peck at the food without eating it. It is proposed that a satiated bird directs its attention to the food in response to the social facilitation effect of the stimulus bir d feeding but eats relatively little. Thus social facilitation seems t o act more on the appetitive phase of feeding behaviour than on the co nsummatory phase. (C) 1996 The Association for the Study of Animal Beh aviour.