Social Facilitation of Eating Behavior in Armadillos

Abstract

The fact that organisms eat more in the presence of other members of the same species than when alone has been well documented in a wide variety of species (James, 1960). In only one study (Platt, Sutker, & James, 1967), utilizing opossums, has this effect not been demonstrated, and these results could be accounted for as a function of the amount of early social stimulation. The current study reports an attempt to demonstrate social facilitation of eating behavior, as evidenced by increased food intake under social versus solitary feeding conditions, in the armadillo (Dasypus novemcinctzls) . Utilizing a method similar to that reported in detail in a previous study with opossums (Platt & James, 1966), 5 adult armadillos were fed, on randomly alternated days, under either a social or isolated condicion. Under the social condicion Ss ate in a large enclosed area 30 in. X 48 in., while under the solitary condition Ss ate in individual enclosures approximately 18 in. X 30 in. Ss were weighed daily upon removal from the home cage, before being placed in the feeding area, and again upon being removed from the feeding area. Ss were allowed 25 min. daily to eat, the daily feeding sessions always starting and terminating at approximately the same time. Water was available ad lib. in the common home cage, and Ss were fed their normal ration, moistened Purina cat chow, during the experiment. Over a period of 22 sessions, 11 under each condition, Ss ate significantly more under the social than under the isolated condition. The results, calculated in terms of food intake as percentage of daily body weight, were analyzed by means of a 2 X 11 repeated measures analysis of variance design. The results were significant for condition of feeding (2; = 7.51; df = 1/8; p < .05) but not for days or condition of feeding X days interaction. These results suggest that the armadillo, like a number of other animals, is responsive to social cues received from the presence of other members of the same species.