Non-invasive hair sampling of Neotropical otters

Abstract: Sampling wild animal populations using non-invasive techniques is advised when dealing with threatened species. Hair samples provide ecological information like species and individual identification. However, hair trapping is scarcely used in otters, due to their aquatic habits. Most studies are with captive individuals, so there is the need to test non-invasive hair trapping methods in otters in the wild. The aim of this study was to develop a simple and cost-effective method to collect hair from otter species in a non-invasive way. The study was carried out in the Paranapanema River, São Paulo State, Brazil, with the Neotropical otter (Lontra longicaudis Olfers, 1818), a protected species. Hair traps (wooden sticks and tree roots with adhesive tape or wax bands) were set during six nights on river banks, otter trails and scent-marking sites. Traps were baited with otter fresh spraints from other river locations. From the 23 traps, 10 (43.7%) were successful in collecting otter hairs, mostly guard-hair. The sticks were much more efficient than the roots at capturing otter hair (70.6.% vs. 0%) as well as adhesive tape when compared to wax (71.4% vs. 0%). Method simplicity and efficiency suggest that it can be a cost-effective way for collecting otter hairs without the need for capturing individuals. This method can be used for: assessment of local otter distribution; collecting otter hair samples for sex and individual identification (by molecular analysis), trophic ecology (by isotopic analyses), ecotoxicology (by contamination analysis) or behaviour ecology (by hormonal and stress levels analysis). More trapping campaigns should be implemented to further test the method's efficiency.

摘要：针对受威胁野生动物种群，建议采用非侵入性技术开展抽样调查。毛发样本可提供物种识别、个体鉴定等生态学信息。然而，受水獭水生栖息习性限制，毛发诱捕法极少应用于水獭类群。现有相关研究多聚焦于圈养个体，因此亟需在野生水獭种群中验证非侵入性毛发诱捕方法的可行性。本研究旨在开发一种简便易行且成本可控的非侵入性水獭毛发采集方法。研究于巴西圣保罗州巴拉那帕内马河（Paranapanema River）开展，研究对象为受保护物种新热带水獭（*Lontra longicaudis* Olfers, 1818）。研究人员在河岸、水獭活动路径与气味标记点布设了为期六晚的毛发诱捕装置，包括以黏附胶带或蜡封绑带固定的木棍与树根，并使用其他河段采集的新鲜水獭粪便作为诱饵。在23个诱捕装置中，10个（43.7%）成功采集到水獭毛发，且以针毛为主。其中木棍诱捕装置的捕获效率显著高于树根（70.6% vs. 0%），黏附胶带的捕获效率亦优于蜡封绑带（71.4% vs. 0%）。该方法兼具简便性与高效性，无需捕获个体即可采集水獭毛发，是一种成本可控的可行方案。此方法可应用于以下场景：当地水獭种群分布评估；通过分子分析开展性别鉴定与个体识别的毛发样本采集；通过同位素分析开展营养生态学研究；通过污染物检测开展生态毒理学研究；以及通过激素与应激水平分析开展行为生态学研究。后续应开展更多诱捕实验，以进一步验证该方法的应用效率。