DEFINING BOUTS OF BEHAVIOR - A 3-PROCESS MODEL

Statistical methods used to derive a bout criterion traditionally rely on 'two-process models'. A model based on three processes can, however, provide a biologically and statistically more satisfactory description of the temporal distribution of behavioural events. Using the log frequency method suggested by Sibly et al. (1990, Anim. Behav., 39, 63-69), the explanatory power of both models was tested by analysing the feeding patterns of 13 wild rats, Rattus norvegicus, recorded in semi-natural conditions. Feeding events were significantly distributed into bouts according to the conventional 'two-process model' but the alternative model involving a third process provided a better explanation of the data in 89% of cases. The 'three-process model', whose biological interpretation is very simple, is likely to be applicable to a number of situations although it is likely to go unnoticed on the commonly used log survivorship plots. Since the two models provide significantly different criteria for defining bouts, these results suggest that investigators should be aware of the explanatory power of additional processes when attempting to derive a bout criterion. © 1993 The Association for the Study of Animal Behaviour. All rights reserved.