The influence of body condition on sexual development of male Brown long‐eared bats (Plecotus auritus) in the wild

Abstract

The relationship between sexual maturity and body condition was examined in a sample of 57 male Brown long‐eared bats (Plecolus auritus) captured in autumn 1984 from nursery roosts in north‐east Scotland (57°N). A direct relationship was found between reproductive status, which was established by external examination of the genitalia, and body weight. No such relationship was established between reproductive status and forearm length. A strong direct relationship was found between reproductive status and an index of body condition (body weight/forearm length). Three of the males examined had distended epididymides, suggesting they were filled with spermatozoa, and that the bats concerned had recently undergone spermatogenesis.Reproductive status also varied between maternity roosts. Bats from roosts in areas with a high proportion of tree cover were more sexually developed, and in better body condition, than bats from roosts in areas with less tree cover.