AN EMPIRICAL-COMPARISON OF FOCAL AND AD-LIBITUM SCORING WITH COMMENTARY ON INSTANTANEOUS SCANS, ALL OCCURRENCE AND ONE-ZERO TECHNIQUES

An empirical comparison of ad libitum and focal-animal scoring of agonistic behaviour in rhesus monkeys, Macaca mulatta, indicated that, although frequencies were underestimated by ad libitum scoring, many ordinal relationships were preserved. Ad libitum scoring missed silent and brief responses and underestimated the participation of younger individuals. Relatively more chasing and less slapping were detected, but both techniques indicated a greater frequency of non-contact forms of aggression, and more slapping than biting in contact aggression. Ad libitum scoring, however, failed to detect the tentative and ambiguous nature of many agonistic interactions engaged in by adult males. An evaluation of alternative methodologies concludes that appropriate uses can be found for all. Ad libitum data can be used for directionality and pilot work. All occurrence scans provide frequency data in special cases but otherwise may approximate ad libitum scoring. Instantaneous scans must take into account mean state durations and one-zero scoring may be the method of choice when acts are clustered and the goal is to predict the probability of at least one such act in a given unit of time. © 1991 The Association for the Study of Animal Behaviour.