Performance of helicopter-based biopsy darting of polar bears (Ursus maritimus) on the spring sea ice

For over 40 years, biopsy darting has been increasingly used to obtain DNA and other samples from cetaceans; however, its application to other species is more recent. We assessed the performance of helicopter-based biopsy darting of polar bears (Ursus maritimus) on the spring sea ice. Our aim was to provide an overview and evaluation of our protocols for others considering helicopter-based biopsy darting. We shot 55 biopsy darts at 46 polar bears. Most darts (n = 51; 93%) hit the bear, but four of these were likely glancing shots that did not collect a biopsy sample. Mean chase time by the helicopter was short (x¯\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\overline x$$\end{document} = 23 s; range = 8–60 s), but chase time was significantly greater for bears with cubs than those without. There was no significant difference in chase time between bears that ran from the helicopter and those that charged it, but missed shots occurred more frequently for bears initially charging the aircraft, necessitating a second shot. We observed minor reactions (flinching or glancing backward) by 24% of the bears to the dart itself; however, all bears had a flight or fight response to the helicopter. All but one dart was retrieved. The dart success rate—the percentage of darts that hit the bear and collected a tissue (skin) sample—was 88%. However, only 53% collected more than a minimal amount of fat. All of the skin samples collected yielded DNA. Our study, along with the experiences of others, demonstrates that biopsy darting of polar bears has potential for genetic tagging of individuals for capture-mark-recapture studies. While we provide further information on equipment, protocols, and performance of helicopter-based biopsy darting, work remains to improve equipment and protocols, and better assess the impacts to affected individuals. We encourage further research on biopsy darting terrestrial mammals to spur technological advancements and guide the development of best practices.