An initial performance review of vaginal implant transmitters paired with GPS collars

Background The vaginal implant transmitter is an effective tool in the study of neonatal survival rates for cervid species. The latest iterations of the vaginal implant transmitter use Global Positioning Systems and ultra-high frequency telemetry technology to create a self-monitoring system in which researchers receive near instantaneous notifications of parturition events via remote transmission. We deployed ultra-high-frequency radio-linked vaginal implant transmitters on 44 adult female white-tailed deer ( Odocoileus virginianus ) and assessed their performance and possible benefits to field research. Results In 2016, 60% of the females expelled transmitters at the birth sites. Failure to locate a birth site was a result of technological failings (20%) and premature expulsions (20%). Following manufacturer updates in 2017, we observed an apparent reduction in technology malfunctions (8%) but similar rates of premature expulsions (33%), which resulted in 58% of radio-linked transmitters expelled at birth sites. We located similar numbers of neonates per device across both years. The likelihood that researchers would locate > 1 neonate at or near the birth site was greater for radio-linked transmitters than has been reported in studies using traditional vaginal implant transmitters. Conclusions Radio-linked transmitters allow researchers to increase sample size, expand spatial distribution of study animals, and reduce personnel requirements.