Eyes, ears, or nose? Comparison of three non-invasive methods to survey wolf recolonisation

Abstract

The development and use of cost-effective and appropriate survey methods to assess species distribution and to monitor range expansion and contraction of wild populations is crucial due to the limited financial resources for conservation. Of particular importance, yet little studied, is the ability to collect information before a wild population is well established, i.e. at the early stages of recolonisation. During 2018 and 2019, we used camera traps, audio recorders, and scat detection dogs simultaneously to investigate composition, detection probability, and territorial extent of a pack of wolves in the Swiss Alps. We compared the efficacy of these survey methods by assessing sampling effort, data obtained, and costs. We show that, under the presented setup, camera traps and scat detection dogs substantially outperformed audio recorders in detecting wolves, representing the packs’ territorial extent, and revealing the number of adult wolves. The detection dogs did not detect pups but, unlike the other methods, allowed the identification of single individuals. The use of four camera traps during 13 weeks, a 24-km-long transect walked with the detection dog, or the use of one audio recorder during 148 weeks were necessary to obtain a comparable wolf detection probability. Our results show that no single method was able to return all information that we hoped to collect. Comprehensive and cost-effective information was best obtained by combining data from camera traps and detection dogs. We suggest both methods to be simultaneously used to successfully investigate wolf recolonisation into historical range.

Conservation detection dogs: A critical review of efficacy and methodology

“…CDD efficacy should be evaluated during training and testing rather than waiting until operational searches to assess performance, however, many published studies simply investigate whether CDD can discriminate the target odour in a simple controlled trial and do not progress to testing the CDD in a field environment under operational conditions. Indeed, of the 67 studies examined in this review, Of studies assessing performance in the field, scat surveys of mammals are the most prevalent with precision rates of between 30.8% to 100% (Beckmann, 2006;Clare et al, 2015;Cozzi et al,…”

“…Indeed, modern guidelines for conservation methods, such as 'What Works in Conservation 2021' by Sutherland et al (2021) along with governmental protocols for target species searches (Thompson et al, 2020), do not include CDD despite their widespread use, which may be indicative of the concerns around their efficacy. Given that conservation suffers from underfunding (Cozzi et al, 2021;Cristescu et al, 2020), the tool used for a project must be worth the cost.…”

“…(2011) achieved rates of 100% meaning all indications were true positives. Of studies assessing performance in the field, scat surveys of mammals are the most prevalent with precision rates of between 30.8% to 100% (Beckmann, 2006; Clare et al., 2015; Cozzi et al., 2021; Davidson et al., 2014; DeMatteo et al., 2014; Furtado et al., 2008; Harrison, 2006; Hatlauf et al., 2021; Hollerbach et al., 2018; Kretser et al., 2016; Orkin et al., 2016; Sentilles et al., 2021; Smith et al., 2003; Statham et al., 2020; Thompson et al., 2012; Vynne et al., 2011). Low rates of precision may occur as it can be difficult for the handler to accurately identify scats visually which can lead to them accidentally rewarding indications on non‐target scats (i.e.…”

How to Choose? Comparing Different Methods to Count Wolf Packs in a Protected Area of the Northern Apennines

“…Some of them showed that different applied methods could lead to similar outcomes, suggesting that the sampling protocol choice should be based on the available resources and ecological features of the study area [ 15 , 16 ]. Conversely, other studies found that only the combination of different methods could ensure reliable results [ 17 , 18 , 19 , 20 ]. Several research projects have been carried out so far to investigate the population ecology of the Italian wolf ( C. l. italicus ) and possible threats to its conservation status, mainly in the central-northern Apennines, through WH [ 21 , 22 ], CT [ 13 , 23 ] and NGS [ 24 , 25 ].…”