Vaginal Implant Transmitters as a Tool for Pronghorn Fawn Capture

Abstract

During a pronghorn (Antilocapra americana) translocation study in New Mexico, USA, in 2014, we outfitted 26 pregnant female pronghorn with vaginal implant transmitters (VITs) to better understand cause‐specific fawn mortality. All VITs were equipped with both temperature and photo (i.e., light) sensors. Partial expulsions were detected from VITs in April 2014, at least 2 weeks prior to fawn observations. In these instances, VITs were exposed to ambient daylight activating the photo sensor, which was “reset” daily after sunset. These false signals likely compromised both battery life as well as detection of actual fawn births as a result of time spent tracking false expulsions rather than focusing efforts on fawn capture. We tracked VITs of 19 females (n = 16 confirmed expelled). Expelled VITs assisted with fawn captures (n = 12) from 8 females. We were unable to capture fawns from some females with VITs because fawns were too old to capture or VIT signal failure limited our ability to correctly determine whether a birth occurred. Failure here is defined as a signal we were unable to hear due either to battery failure or geographic location of the VIT post‐expulsion. We also opportunistically captured fawns, either by monitoring and observing females outfitted with very‐high‐frequency (VHF) collars or using long‐range observations of unmarked females. Opportunistic captures resulted in fawn captures (n = 4) from 3 females with only VHF collars, and 13 fawns from 13 unmarked females. Fawn capture success from females whose VIT expelled was greater because fawns were smaller and less likely to flee. To minimize false expulsion signals in VITs, we recommend 1) modification of VIT wings to maintain position inside the vaginal canal until parturition, and 2) change VIT design to specifically fit pronghorn (i.e., design VITs using specific pronghorn vaginal canal measurement to ensure better VIT fit) to prevent premature partial or total expulsion. © 2019 The Wildlife Society.

A novel intrauterine satellite transmitter to identify parturition in large sharks

“…Used in terrestrial systems, intrauterine tags, or vaginal implant transmitters (VITs), are radio transmitters inserted into the vaginal canal of a female ungulate, and sealed with a flexible material, to be expelled at parturition ( 21 ). Since the 1980s, VITs have been used to identify the timing and location of parturition sites of ungulates for estimating juvenile survival ( 21 ).…”

“…Used in terrestrial systems, intrauterine tags, or vaginal implant transmitters (VITs), are radio transmitters inserted into the vaginal canal of a female ungulate, and sealed with a flexible material, to be expelled at parturition ( 21 ). Since the 1980s, VITs have been used to identify the timing and location of parturition sites of ungulates for estimating juvenile survival ( 21 ). However, to date, this tool had never been applied to marine systems, likely owing to the inherent technical and logistical challenges of working in open aquatic systems and with large marine megafauna.…”

Optimizing methods for capturing neonate elk when using vaginal implant transmitters

“…Capturing neonate ungulates with the aid of VITs has advantages over alternative capture methods, which often are challenging and time-intensive (Carstensen et al 2003, Swanson et al 2008, Conant et al 2020.…”

“…Capturing neonate ungulates with the aid of VITs has advantages over alternative capture methods, which often are challenging and time‐intensive (Carstensen et al 2003, Swanson et al 2008, Conant et al 2020). Neonates are typically captured without VITs through the observation of potential post‐parturition behaviors by adult females (Vore and Schmidt 2001, Vreeland et al 2004, Seward et al 2005, Hurley et al 2011, Pitman et al 2014).…”

“…Very high frequency (VHF) transmissions produced by the VIT allow researchers to locate expelled VITs and parturition sites. At least 9 species of ungulates in North America have been studied using VITs: bighorn sheep ( Ovis canadensis ), bison ( Bison bison ), elk ( Cervus canadensis ), feral pigs ( Sus scrofa ), moose ( Alces alces ), mule deer ( Odocoileus hemionus ), muskoxen ( Ovibos moschatus ), pronghorn ( Antilocapra americana ), and white‐tailed deer ( Odocoileus virginianus ; Kaze et al 2016, Conant et al 2020, Schmidt et al 2020).…”