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

Abstract

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.

Continental synchrony and local responses: Climatic effects on spatiotemporal patterns of calving in a social ungulate

“…While this difference is nontrivial (23%), there are considerable advantages in terms of time and energy compared with other methods. Indeed, among the existing methods to detect calving events, most are either invasive (e.g., vaginal implants) or require intensive aerial or ground surveys (Adamczewski et al, 2019; Dion et al, 2019).…”

Improving the precision and accuracy of wildlife monitoring with multi‐constellation, multi‐frequency GNSS collars

“…Nevertheless, habitat‐biased locations and imprecise movement paths, also affected by the fix interval, may become unsuitable for ecological analyses. The recent scientific literature contains numerous examples of how GPS collar data are used in wildlife monitoring for habitat modeling (Laguna et al 2021), and identifying animal movement and landscape use (Wittemyer et al 2019, Gray et al 2022), migratory strategies (Peterson et al 2022), predation sites (Irvine et al 2022), birth sites (Dion et al 2019, Marchand et al 2021, Hooven et al 2022), and capture locations (Hampton et al 2020, Bengsen et al 2021), or to define social behavior (Davis et al 2018, Wielgus et al 2021). Improvements to GNSS technology allow for more reliable data collection from collars; thus, new ecological questions can be investigated.…”

Using low-fix rate GPS telemetry to expand estimates of ungulate reproductive success

“…Established field methods to obtain these data included opportunistic sampling of reproductive organs from harvested females [17], pregnancy determination via palpation [18,19] or serological analysis [20][21][22], characterization of juvenile/adult ratios from visual observation [21,[23][24][25], and radio-marking and monitoring of juveniles [26][27][28]. Vaginal implant transmitters (VITs) have become a reliable field method for determining the timing and location of ungulate parturition [29][30][31]. VITs allow researchers to rapidly deploy to parturition sites and mark neonates for survival studies, thereby reducing potential bias inherent in other methods that often rely on opportunistic captures of older individuals [32,33].…”

“…Population expansion of elk and an increase in annual harvest highlight the need for up-to-date estimates of demographic parameters to inform population models [60]. In an effort to update vital rate estimates used in the state's elk population model, we initiated a study of reproductive rates and neonatal survival using "natal-linked" GPS collar systems with paired VITs [31].…”