THE EFFECT OF CONTRACEPTIVE IMPLANTS ON THE BEHAVIOR OF FEMALE RODRIGUES FRUIT BATS, PTEROPUS-RODRICENSIS

This study investigated the effects of a melengestrol acetate contrace ptive implant on the behavior of captive Rodrigues fruit bats (Pteropu s rodricensis). Eighteen female bats (nine controls and nine implanted animals) were studied over three 4 week periods: prior to implantatio n, immediately postimplantation, and 6 months postimplantation. The on ly significant differences found 6 months postimplantation were that t ime spent hanging alert decreased in both groups and, concurrently, am ount of time spent engaged in other activities, most noticeably social interactions, increased. In connection with this, the number of neare st neighbors increased. However, these changes were seen in all bats a nd were also associated with the increasing size of the resident colon y. There were no significant differences between the two groups of bat s in the number of nearest neighbors or sexual partners over the cours e of the study. The physical effects of the contraceptive implants, in creased weight gain and retarded hair regrowth above the incision site , were very clearly shown. There was a 22% rate of rejection/loss of t he implants. None of the implanted bats produced offspring postimplant ation. This study has shown that melengestrol acetate implants are an effective way to limit reproduction in female Rodrigues fruit bats, at least in the short term, and have no effect on the behavior of this h ighly social species. (C) 1996 Wiley-Liss, Inc.