Evaluation of expandable global positioning system collars for white-tailed deer fawns

Abstract

Integrating Global Positioning System (GPS) technology with expandable collars will allow researchers to more accurately and efficiently investigate survival of white-tailed deer (Odocoileus virginianus) fawns. We tested fit and function of 5 expandable GPS collar prototypes on white-tailed deer fawns and conducted behavioral observations during the first 12 weeks of life at the Whitehall Deer Research Facility, Athens, Georgia, USA, during 2018–2020. We fitted 46 fawns with 5 prototype collar designs and ear-tagged 15 control fawns without collars. Prototype collars differed in expandable band materials. Premature expansion and breakage of collar bands composed of cotton and rubber was a problem that resulted in freely moving collars and displacement to the waist of fawns. Fawns retained prototype collar designs with cotton and rubber band materials for a mean 101 (±46 [SD]) and 70 (±37) days, respectively. For 2 collar designs with expandable bands composed of nylon and rubber, fawns retained collars for a mean 246 (±156) and 306 (±99) days, respectively. Vectronic (v1.0 and v2.0; VECTRONIC Aerospace GmbH, Berlin, Germany) and Telonics v2.0 (Telonics Inc., Mesa, AZ, USA) collared fawns were 16–21% less likely to be observed standing compared to uncollared fawns. Bedded Vectronic (v1.0 and v2.0) and Telonics v2.0 collared fawns were 19–28% less likely to be observed with their head up compared to uncollared fawns. Bedded fawns with collars were 11–16% more likely to be observed with their head tilted compared to bedded fawns without collars. Vectronic (v1.0 and v2.0) and Telonics v2.0 collared fawns were 25–34% less likely to exhibit vigilance compared to uncollared fawns, and all collared fawns were 22–37% more likely to exhibit sleeping than uncollared fawns. We recommend that GPS collar designs we evaluated undergo additional modifications before deployment in the field, including improved stitching patterns and threads to facilitate more gradual collar expansion, smaller battery housings and improved weight distribution to mitigate behavioral concerns, and smaller band circumferences to improve collar fit across time.