Performance of detection dogs and visual searches for scat detection and discrimination amongst related species with identical diets

Abstract

Ecology often faces the problem that many threatened species are highly elusive but also conflict-laden. Thus, proper monitoring data are inevitable for their conservation and management. Indirect monitoring through scats is frequently used for such species, but scats of related species or species with similar diet are often visually indistinguishable. Since genetic methods for species identification are time-consuming and cost-intensive, a verification of the target species beforehand would be extremely beneficial in reducing effort to the analysis of the target species only. Such species discrimination could be provided through species-specific scat detection dogs. Therefore, we evaluated the reliability of species-specific scat detection dogs for two mustelid species feeding on identical diets: the Eurasian otter (Lutra lutra) and the American mink (Neovison vison), both of which are conflict-laden and increasing their populations and distribution ranges in central Europe. Their scats resemble each other in morphology and odour, exacerbating the differentiation even for experts. To evaluate whether detection dogs can reliably discriminate between related species feeding on similar diets and if their use would be beneficial, we tested their abilities against those of humans. We first proved that scat characteristics are not statistically different between species. Likewise, visual species identification through people with different experience levels was only partly successful. Experts showed higher average accuracy (0.89) than non-experts (0.72 and below), but detection dogs (4 dogs) were able to discriminate otter and mink scats under laboratory conditions with an accuracy of 0.95. Moreover, otter scat detection dogs found up to four times more scat samples in the field, were twice as fast as human searchers and found an almost equal number of scats with different characteristics, while humans mostly found older and larger scats placed on hotspots. We conclude that using detection dogs for species identity will allow subsequent laboratory analyses to be species-specific and avoid spending time and money on laboratory work of the wrong species. It also provides more precise and unbiased information about the target species.

Benefits of incorporating a scat-detection dog into wildlife monitoring: a case study of Pyrenean brown bear

“…This situation facilitates scat detection by the dogs but not necessarily by humans. Indeed, because they operate largely by scent rather than sight, dogs assist in finding visually concealed targets, such as scats hidden below dead leaves, in grass or under dense understory (see also Grimm-Seyfarth et al 2019). In addition, dogs help in minimizing sampling bias towards scats with traits that enhance their visibility (e.g.…”

“…Early on, the puppy expressed enthusiasm for a toy then learned to associate brown bear scats with the reward of playing with this toy (Sentilles et al 2016). The dog training consisted of hiding bear scats in vegetation and bringing the dog to the area and allowing it to search off leash, so that searching was not biased towards a particular location by the handler (Grimm-Seyfarth et al 2019). The dog was taught to lie down facing the scat and bark after locating a brown bear scat.…”

“…In the Pyrenees, bear cub scats, in particular, can be easily confused with those of red foxes (Vulpes vulpes Linnaeus, 1758) and European badgers (Meles meles Linnaeus, 1758). In North America, it has been fairly well established that large carnivore scat detection can be improved through the use of scat detection dogs (see references in Orkin et al 2016, Grimm-Seyfarth et al 2019. In 2013, we therefore decided to incorporate this technique in future efforts to monitor the Pyrenean brown bear population, by training a dog from an early age to detect bear scats.…”

Jackal in hide: detection dogs show first success in the quest for golden jackal (Canis aureus) scats

“…For many species, the analysis of fresh scats provides a secure, reliable and non-invasive method to receive genetic information (Frantz et al 2003;Janečka et al 2008;DeMatteo et al 2014). The substantially overlapping food niches of closely related species (Lanszki and Heltai 2010;Akrim et al 2019;Grimm-Seyfarth et al 2019) complicate the identification of scats based on morphological criteria (Foran et al 1997;Baines et al 2013;Spitzer et al 2019). In some cases, only DNA analyses can remove doubts about the origin of collected scats.…”

“…In contrast, we assume that humans are not able to distinguish reliably between golden jackal scats and those from closely related canid species, especially in areas of coexistence with the red fox (Vulpes vulpes), a species widespread all over Europe. Moreover, humans have a much smaller overall detection success than dogs (Böcker 2016;Ramsey et al 2017;Grimm-Seyfarth et al 2019).…”