title: Responses of male and female domestic chicks to a startling stimulus and the effects of a tranquilliser.
abstract: The present study examined sex differences in the responses of domestic chicks to novelty and exposure to a startling stimulus. In the first experiment, 7-day-old male and female chicks were placed individually in a novel environment for 10-min periods. After 5 min, half of the chicks were exposed to a loud bell. Males showed more passive behaviour such as freezing, sitting and eye-closure and were less active and less vocal than females, both before and after exposure to the bell. Ringing the bell increased immobility and reduced activity and vocalisation in both sexes thus confirming its effectiveness as a fear-elicitor. The second experiment involved injecting males and females with either a tranquilliser (Pacitran) or water. Immobility decreased whereas peeping and walking increased in the Pacitran-injected groups both before and after the bell was rung. The behaviour of untranquillised, water-injected females was comparable to that of Pacitran- treated males. These results may reflect sex differences in either the form of fear responding or the underlying levels of fearfulness; the latter seems more likely.
authors.affiliation: Agricultural Research Council's Poultry Research Centre, King's Buildings, West Mains Road, Edinburgh EH9 3JS Great Britain.
authors.forename: R B
authors.initials: RB
authors.lastname: Jones