The vocalizations of suckling piglets were studied during brief tests which involved social isolation, restriction of movement, and exposure to unfamiliar surroundings. Similar trends were shown in most cases by the three classes of call studied - closed mouth grunts, open mouth grunts, and squeals. The rate of calling was much lower when a piglet was in the home pen than when alone in an unfamiliar pen, and more calls were given in both situations when the animal’s movement was restricted by caging. The presence of the dam and four littermates in unfamiliar surroundings caused a large reduction in calling, part of which was seen with only the dam present, and part with only the littermates. Provision of familiar bedding in the unfamiliar situation had no effect. Aspects of piglets’ adaptation to environmental and social change are discussed.
Fraser, D. (1975). Vocalizations of isolated piglets. II. Some environmental factors. Applied Animal Ethology, 2(1), 19-24.