INTRODUCTION

Social organization in bats varies enormously. At one extreme, animals may remain solitary for much of the time. Several megachiropteran species are found solitarily or as mother-young pairs for most of the year (Bradbury 1977). On the other hand, roosts of the Brazilian free-tailed bat Tadarida brasiliensis encompass some of the largest aggregations of vertebrates known. Maternity colonies of this species often contain millions of individuals, with up to 30–50 million bats estimated at one site earlier this century (Wilson 1997). Most species have varied social organizations according to season, and according to the age and sex of the individuals concerned (Bradbury 1977). Most bat species clearly have ample opportunities for social interactions, both at roosts and away from them, for example at foraging sites.

Several authors (e.g., Bradbury 1977; Fenton 1985; McCracken 1987; Wilkinson 1995) have reviewed aspects of social organization and communication in bats. Although much attention has been paid to describing different patterns of social organization, and to communication among adult bats and mother-young pairs, there are few data on the ontogeny of social behavior. Most studies at maternity colonies have concentrated on behavior of females and on mother-young interactions, rather than on the development of social behavior in infants. In this chapter I will attempt to fill this gap by reviewing several recent studies that have addressed the ontogeny of behavior, especially behaviors that have a social context.

I begin by examining the scant literature on social interactions among pups in maternity colonies. I will then address social interactions between mothers and pups.