Introduction

In this Chapter we discuss methods for estimating the time spent in different behaviors. The Chapter is intended primarily for researchers who collect behavioral data, and we have therefore felt justified in discussing practical problems in some detail. We also assume a moderate familiarity with the goals of behavioral sampling and the practical difficulties often encountered. Lehner (1996) and Martin and Bateson (1993) discuss many other aspects of measuring and describing behavior as well as some of the points discussed here.

By ‘sampling behavior’ we mean that one or (usually) more types of behavior have been defined, and the objective is to estimate how often they occur. ‘How often’ may mean any of the following: proportion of time spent in the behavior, frequency of the behavior (e.g., number/hour), average duration of the behavior. All three estimates might be of interest for some behaviors (e.g., fights with intruders) while for other behaviors this might not be true. For example, it might be feasible to count the number of pecks/minute but difficult, due to the speed with which a peck occurs, to estimate either the average duration of a peck or the proportion of time spent pecking.

Defining behaviors and bouts

A first task in designing the sampling plan is to define the behaviors. The definitions should be specific enough that different observers would interpret them the same way and that they can be explained clearly. Defining positions of the body (head up/head down), type of movement (walking, running, flying), and different types of vocalizations generally meet these criteria better than broader terms such resting, feeding or scanning for predators.