Invasive or non-invasive trapping of otters and the use of scent lures and baits: a review

Animals are often trapped to learn more about a species’ behavioural ecology, either invasively with live traps or non-invasively with hair- or camera traps. The use of scent lures or baits can help to attract animals to the trap site. The aim of this study was to identify the best and most efficient trapping techniques and scent lure or bait for research on Eurasian otters ( Lutra lutra ). The systematic literature review, in accordance with PRISMA guidelines, was designed to include results for all otter species. It recovered 16 papers, most published between 2011 and 2020 covering six otter species. This review identified six different main trapping methods (net traps, leghold traps, cage traps as live- or hair traps, suitcase traps, hair traps using sticks, and camera traps). Scent lures were only utilized in the hair- and camera trapping studies. Due to the limited comparability of the studies, the most effective trapping or scent lure/bait method could not be concluded. The review therefore provides the pros and cons of these various capture techniques for otter research. This study highlights the need for more research on otter trapping focused on the use of scent lures or baits, trap placement, amounts of bycatch, and animal welfare to trap otters in the most effective and least harmful way.