INTRODUCTION

There are many reasons to capture study animals. They include marking or radio-collaring (Chapter 10), taking morphological measurements (Chapter 9), or biological samples (Chapters 1 and 8), and estimating age and condition. For small nocturnal primates, capture is essential to radio-tag animals for direct observation, the most effective method of determining the spatial distribution and social interactions of individuals and estimating population densities (Chapter 6; Sterling et al., 2000). Historically, studies in which wild, larger-bodied, primates are habituated for long-term observation have rarely included capture, perhaps because researchers have been understandably wary of its effects on subsequent behaviour and habituation (Chapters 2 and 11). However, a survey of more than 120 studies that combined observation with capture, and which involved about 65 primate species, showed that a careful capture–release programme using trapping will not cause a previously habituated population to change its behaviour towards human observers, and will not be associated with excess mortality or serious injury (Jolly & Phillips-Conroy, 1993 and unpublished data). Changes in ranging habits will be temporary at worst, and basic social organization and structure will not be affected. The survey also provided a comparison between capture methods. Trapping has been used most often to catch diurnal-terrestrial and nocturnal-arboreal species. Diurnal-arboreal primates (apart from callitrichines) have generally been captured by darting (Chapter 8), a bias that seems unjustified.