5.2 Sexing and ageing 5.2.1 Sex and reproductive assessment Reliable assessment of the reproductive status of bats is important to field and laboratory studies. 5.1 FIELD IDENTIFICATION bats A. M. Hutson & PA. Racey However, it is often difficult to assess age and reproductive status accurately (see Kunz, 1988; Crighton & Krutzsch, 2000). 5.2.2 Sexing and sexual dimorphism Males of all species have a conspicuous penis. Females have a single anterior pair of mammary glands and nipples. Pubic false nipples are found in rhinolophids and are used by young bats to hang onto their mothers. Although sexual dimorphism is well documented in bats, with females larger than males, it is seldom marked enough to be of use as afield characteristic. Males make characteristic social calls during the mating season, which may allow identification of sex in the future.