Effects of Environmental Conditions on Performance of Vaginal Implant Transmitters

ABSTRACT  Vaginal implant transmitters (VITs) are increasingly used to facilitate capture of neonatal ungulates. Environmental conditions potentially have a significant influence on performance of VITs; however, effects on VIT performance largely are unknown. We exposed VITs to conditions reflective of those present during white-tailed deer fawning season in Alabama and examined effects of ambient air temperature and vegetative structure on their performance. Performance of VITs was inversely related to ambient air temperature, and VIT performance increased along with increasing amounts of shade provided by vegetation. Current devices likely will perform relatively well if expelled in areas where ambient air temperatures are below the user-defined pulse switch point and habitat conditions provide shade. Performance of VITs will be severely compromised if expulsion occurs in areas where ambient air temperatures are above the user-defined pulse switch point and devices are exposed to direct sun. Individuals interested in utilizing VITs should consider local climate and vegetative characteristics prior to initiating projects to evaluate if devices will meet performance requirements.