Seeking efficiency with carnivore survey methods: A case study with elusive martens

Abstract

Obtaining reliable information on species distributions is often the first step in conservation. Distribution information can be used to focus survey efforts to estimate population size and examine drivers of occupancy or other population parameters. We compared detection rates and survey costs for 2 techniques (remote cameras and scent detection teams) used to evaluate distribution of a rare carnivore, Humboldt subspecies of Pacific marten (Martes caurina humboldtensis). We used remote cameras at randomly placed sites in coastal Oregon, USA, to compare camera set type (baited, unbaited), bait height (<0.5 m, 1.37 m), and bait types (chicken and lure, cat food) for a 21‐day survey period during winter (27 Jan–12 Apr) and summer (04 Jul–14 Oct) 2015. When a marten was detected, we completed an additional survey within 25 m. Scent detection teams (human handler and dog) performed area‐constrained searches for scat deposited. We used a Bayesian occupancy model to compare detection probabilities for baited camera treatments. We detected martens at 26 sites, and offset stations detected martens at 15 of 24 sites (62.5%). Survey‐level detection probability for martens (the probability of detecting ≥1 marten during a survey) was high for the camera survey during summer and winter (estimates ranged from 60% to 99% and 33% to 82%, respectively), and similar for all treatments. We surveyed 50 sites with both remote cameras and scent detection teams 25 April–25 May 2015. Of 33 sites with ≥1 marten detection, 36.4% of units had a marten detected only by scent detection teams, 30.3% only by remote camera, and 33.3% by both techniques. When the objective was marten detection, survey costs were less for scent detection teams. For identifying individual martens and their sex, cameras paired with hair snares were more cost‐efficient. Scent detection teams provided a complementary method to baited remote cameras for assessing distribution. Using multiple techniques provided an opportunity to quantify limitations of survey methods. © 2018 The Wildlife Society.

Status of Pacific Martens (Martes caurina) on the Olympic Peninsula, Washington

“…Nonetheless, recent climate trends involving increased winter temperatures and decreased snowfall in western Washington could reduce available habitat and refugia at high elevations and further threaten the viability of montane marten populations (Dawson et al 2011, Pauli et al 2013, while increasing the extent of available habitat for fishers , Halofsky et al 2017, Suffice et al 2017. Increased surveillance for martens involving more intensive and efficient survey methods, such as scent detection dog teams (Moriarty et al 2018) or over-winter remote camera surveys, would help delineate other areas where martens still occur on the Olympic Peninsula. Further, surveys designed to collect additional genetic samples are essential for evaluating the genetic diversity and demographic characteristics of these potentially threatened marten populations.…”

Describing vegetation characteristics used by two rare forest-dwelling species: Will established reserves provide for coastal marten in Oregon?

“…Scent detection teams consisted of a handler and a dog with at least 480 hours of training using lab and simulated field trails (e.g., hidden scats on training boards and in the duff). Detection dog team surveys occurred near recent records of Humboldt marten locations identified using a stratified random design (see [37] for methods). During winter 2015, field teams surveyed 74 randomly located sample units with 2 remote cameras and detected Humboldt martens at 11 locations [26, 37].…”

“…Detection dog team surveys occurred near recent records of Humboldt marten locations identified using a stratified random design (see [37] for methods). During winter 2015, field teams surveyed 74 randomly located sample units with 2 remote cameras and detected Humboldt martens at 11 locations [26, 37]. Detection dog teams conducted time- and area-constrained search of 1 km 2 areas centered around all 11 remote camera detections and 11 random remote camera locations without prior Humboldt marten detections.…”

“…Surveys occurred for at least 6 hours within each area and dog teams were unaware as to whether a Humboldt marten was detected prior. We assumed this level of effort would allow adequate effort to locate scats, especially in areas that Humboldt martens used more frequently [37]. We assume this technique identified a mixture of resting and foraging locations since latrines were often located at martens’ resting areas.…”

Habitat selection and spatiotemporal interactions of a reintroduced mesocarnivore

“…We placed bait at this height to keep the bait in the frame while having a substantial portion of foreground visible. Moriarty et al () found no difference in detection of Pacific martens ( Martes caurina ) with bait placed at <0.5 m or 1.4 m. We placed bait north of cameras (with few exceptions) to minimize sun glare in photos (Fig. ).…”