Hair Trap Research Articles

Cascading effects of mammal host community composition on tick vector occurrence at the urban human–wildlife interface

AbstractHabitat fragmentation and host community composition are implicated as key drivers of changing tick populations and tick‐borne pathogen dynamics, altering infection risk through coupled socioecological pathways that mediate interactions between tick vectors, vertebrate hosts, and humans. Patterns of host diversity may be particularly idiosyncratic across urbanized landscapes, due to trade‐offs between extreme fragmentation that reduces habitat suitability and access, and human activities that artificially increase resource availability for wildlife. We used camera and hair trap surveys and tick sampling to identify links between landscape composition and configuration, the mammalian host community, and the presence of three tick vector species at a human–wildlife interface in New York City, an emerging area within an endemic region for several tick‐borne diseases. We found that human infrastructures, such as the presence of fences in yards, could affect mammal host community composition by changing the “hardness” of edges between urban greenspaces and residential areas. We identified yard‐ and broader landscape‐level features associated with the presence of urban mammal species, and identified cascading effects of host community composition on tick distribution in yards, suggesting management implications for the mitigation of human exposure to tick‐borne pathogens. In particular, we identified a possible role of ubiquitous mesomammals, such as raccoons (Procyon lotor), in transporting Amblyomma americanum ticks between parks and neighboring residential yards, and confirmed the key role of white‐tailed deer (Odocoileus virginianus) for introducing Ixodes scapularis ticks into yards. Our results challenge assumptions that biodiversity loss in human‐modified areas always increases the risk for tick‐borne diseases. Instead, we found many residential sites had higher mammal species richness and higher detection of low reservoir competent (“dilution”) hosts for Borrelia burgdorferi, such as opossums (Didelphis virginiana), than paired forested greenspaces. Our study highlights the importance of disentangling the mechanisms mediating tick‐borne disease hazard as a critical first step toward reducing urban tick‐borne disease risk.

The wildcat (Felis s. silvestris) in the Mediterranean forest: sighting through photo-trapping and non-invasive hair collection for genetic purposes

The European wildcat (Felis silvestris silvestris) is a mesocarnivore species widely distributed in Europe, from Eastern Europe to Portugal and from Scotland to Italy. Recent biogeographical studies of wildcat populations have endeavoured to assess in detail the various issues that pose a threat to this species, including hybridization with domestic cats. The use of non-invasive sampling methods supported by photo-trapping and some attractants has made it possible to gather genetic material for the detection of native wildcats in locally threatened populations, some of which live in the Iberian Peninsula. Testimonies of naturalists, hunters and farm workers led our team to choose specific areas in two large territories of Mediterranean forests where the presence of wildcats has been historically attested: the Almonte River basin and the Sierra de San Pedro Mountains. Between 2014 and 2018, non-invasive hair sampling was performed using valerian (Valeriana officinalis) as an attractant and supported by photo-trapping to guarantee the collection of genuine biological material (hair samples). The hair samples were genetically assessed by sequencing the nuclear gene IRBP (interphotoreceptor retinoid-binding protein) and the mtDNA gene ND4 (NADH dehydrogenase subunit 4). Despite the low density of wildcats, this combined protocol proved to be an applicable tool for detecting the presence of elusive wildcats and other mesocarnivore species in this remote region of southern Europe. In addition, non-invasive hair trapping contributes to the collection of genetic material from current wildcat populations. This procedure could enhance future management actions focused on collecting quality individualized biological material.

Wild boar effects on hair‐tube sampling

AbstractHair tubes are one of the most effective tools for sampling small‐mammal assemblages. Despite their efficiency, they can be damaged by wildlife. We quantified wildlife‐induced disturbance of hair‐tube sampling in the Monte Pisano mountain system in Italy. At each site we tied 2 tubes together to form a hair trap and placed them in 3 different areas. We measured disturbances by counting the number of hair traps disturbed and identified the species that caused damage with cameras. Although approximately 27% (n = 164/600) of hair traps were disturbed, 2 hair traps/site allowed us to collect data from 97% of site checks from undisturbed and retrieved hair traps. Wild boars (Sus scrofa) were attracted to hair traps by olfactory and acoustic signals and caused the most disturbances. Displaced tubes detected a similar number of hairs and number of species as undisturbed tubes; species richness estimates that include retrieved displaced tubes should provide reliable data. To avoid data loss when conducting hair‐trap monitoring, we suggest using ≥2 hair traps per site.

An attempt to evidence post-fire adaptation of red fox diet in a Mediterranean area

Although fires are common in Mediterranean ecosystems, there are substantial knowledge gaps regarding post-fire shifts in animal diets, especially for carnivores. Red fox Vulpes vulpes is a generalist medium-size carnivore known to have a positive post-fire response, probably due to increased prey availability or facility to hunt. As small mammals are often one of its primary food categories, and early successional visitors of post-fire habitats, we hypothesize a change in red fox diet composition in the warm season after a fire. Hair trapping and scat collection were used to investigate selection of small mammals in a typical Mediterranean region, 3 years after a fire. The diet composition of the fox was compared with that of the fox in the same area in 1992, and with other undisturbed Mediterranean areas. Diet selection was evaluated through the Forage ratio and single resource preference tests. Red fox diet was consistent with other Mediterranean areas, with fruits and seeds, invertebrates, and small mammals being the most consumed categories. However, small mammals were consumed significantly less than in 1992, while fruits and seeds significantly more. Resource selection analysis indicated avoidance for some ground-foraging small mammals, including Crocidura spp. house mouse Mus domesticus and voles, whereas Apodemus spp. were selected. Arboreal-foraging species, e.g. red squirrel Sciurus vulgaris and garden dormouse Eliomys quercinus were used in proportion to their availability. We concluded that this mesocarnivore had high feeding plasticity and exploited various resources according to their availability and catchability. Future studies are needed to further investigate red fox and other carnivores’ food shifts after fire disturbance, including various seasons, other successional stages and competition within predator guilds.

Shooting for abundance: Comparing integrated multi‐sampling models for camera trap and hair trap data

AbstractAbundance estimation is a vital goal in wildlife monitoring. Camera‐traps are a tool to survey wildlife populations noninvasively and can be used for abundance estimation if individuals are identifiable. However, for species without individual identification characteristics, camera‐trap surveys have often been combined with some other survey method such as capture‐recapture (CR, using traditional tags or DNA through hair snags or scat) to inform an integrated model. We discuss and apply two integrated models involving presence‐absence data from camera traps and CR data from hair traps to compare bias and precision to estimate the population density of grizzly bears of the central Rocky Mountains of Alberta, Canada. Unlike many other studies, we found that integrating presence‐absence data with CR data does not improve the precision of the density estimates. The possible reasons for such results are discussed in detail.

Noninvasive sampling of mountain lion hair using modified foothold traps

AbstractAlthough genetic analysis is an increasingly affordable option for wildlife studies, obtaining high‐quality samples from cryptic carnivores remains difficult. To address this, we modified and tested 20.3‐cm (8‐inch) foot snares in unbaited trail sets for noninvasive collection of hair samples from mountain lions (Puma concolor). We deployed 22 hair traps in the Black Range in southern New Mexico from May to November 2017, monitored by remote cameras, at 66 locations for 1,618 trap nights ( = 24.5 nights, SD = 7.2 nights). Photos indicated 20 instances of mountain lions passing within 2 m of a hair trap and we collected 7 mountain lion hair samples, which averaged >20 hairs/sample. All samples contained hair with visible roots and were identifiable to species; 6 of the 7 (85.7%) yielded sufficient DNA for individual identification. We attributed failure to obtain samples to 3 primary causes: individual trap saturation (2 instances), trap failure (2 instances), and non‐trigger events (9 instances). Black bears (Ursus americanus) and heavy rains were the primary sources of disturbance to hair trap sets, contributing to individual trap saturation and trap failure. We speculate that low trigger rates were associated with pan tension having been set too high in the first month of the study, as well as disturbance of hair traps or leading foot placements by nontarget species. We discuss strategies to increase hair sample collection rates, including seasonal use of hair traps, more selective placement on the landscape, and altering physical attributes of the hair traps. The quality of hair samples we collected and subsequent amplification rates indicated that, along with proper deployment strategies, hair traps are a viable tool for noninvasively collecting genetic material for individual identification of mountain lions and other elusive species.

Breaking down population density into different components to better understand its spatial variation

BackgroundPopulation size and densities are key parameters in both fundamental and applied ecology, as they affect population resilience to density-dependent processes, habitat changes and stochastic events. Efficient management measures or species conservation programs thus require accurate estimates of local population densities across time and space, especially for continuously distributed species. For social species living in groups, population density depends on different components, namely the number of groups and the group size, for which relative variations in space may originate from different environmental factors. Whether resulting spatial variations in density are mostly triggered by one component or the other remains poorly known. Here, we aimed at determining the magnitude of the spatial variation in population densities of a social, group-living species, i.e. the European badger Meles meles, in 13 different sites of around 50 km2 across France, to decipher whether sett density, group size or proportion of occupied sett variation is the main factor explaining density variation. Besides the intrinsic factors of density variation, we also assessed whether habitat characteristics such as habitat fragmentation, urbanisation, and resource availability, drove both the spatial variation of density components and local population densities.ResultsWe proposed a new standardised approach combining use of multiple methods, namely distance sampling for estimating the density of occupied sett clusters, i.e. group density, and camera and hair trapping for genetic identification to determine the mean social group size. The density of adult badgers was on average 3.8 per km2 (range 1.7–7.9 per km2) and was positively correlated with the density of sett clusters. The density of adult badgers per site was less related to the social group size or to the proportion of occupied sett clusters. Landscape fragmentation also explained the spatial variation of adult badger density, with highly fragmented landscapes supporting lower adult densities. Density components were linked differently to environmental variables.ConclusionsThese results underline the need to break down population density estimates into several components in group-living species to better understand the pattern of temporal and spatial variation in population density, as different components may vary due to different ecological factors.

Population genetic structures at multiple spatial scales: importance of social groups in European badgers

AbstractPopulation viability and metapopulation dynamics are strongly affected by gene flow. Identifying ecological correlates of genetic structure and gene flow in wild populations is therefore a major issue both in evolutionary ecology and species management. Studying the genetic structure of populations also enables identification of the spatial scale at which most gene flow occurs, hence the scale of the functional connectivity, which is of paramount importance for species ecology. In this study, we examined the genetic structure of a social, continuously distributed mammal, the European badger (Meles meles), both at large spatial scales (among populations) and fine (within populations) spatial scales. The study was carried out in 11 sites across France utilizing a noninvasive hair trapping protocol at 206 monitored setts. We identified 264 badgers genotyped at 24 microsatellite DNA loci. At the large scale, we observed high and significant genetic differentiation among populations (global Fst = 0.139; range of pairwise Fst [0.046–0.231]) that was not related to the geographic distance among sites, suggesting few large-scale dispersal events. Within populations, we detected a threshold value below which badgers were genetically close (< 400 m), highlighting that sociality is the major structuring process within badger populations at the fine scale.

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.

No flood effect on recruitment in a Louisiana black bear population

ABSTRACTA flood event in 2011 had minor impacts on apparent survival and movement probabilities of a small, isolated population of Louisiana black bears (Ursus americanus luteolus) in the Upper Atchafalaya River Basin, Louisiana, USA. However, the potential effects of the flood on recruitment of juveniles into the population, then listed as threatened under the United States Endangered Species Act, were not evaluated. We used hair trapping data collected from 2007 to 2015 and Pradel temporal symmetry models in a robust‐design framework to investigate changes in per capita recruitment that could have resulted from the flood. We detected 91 bears (37 M:54 F) within the flooded area during our study period, ranging from 21 to 44 individuals/year. Models that tested for reduced recruitment resulting from the flood were not supported more than models with constant recruitment, and the population growth rate did not decline. Although we documented marginally lower recruitment following the 2011 flood, lag effects and detectability biases complicated our analysis. We suggest that wildlife managers continue monitoring recruitment and survival in this recently delisted black bear population given the potential for heightened flood frequency and severity in the future. © 2017 The Wildlife Society.

Grizzly Bear Noninvasive Genetic Tagging Surveys: Estimating the Magnitude of Missed Detections.

Sound wildlife conservation decisions require sound information, and scientists increasingly rely on remotely collected data over large spatial scales, such as noninvasive genetic tagging (NGT). Grizzly bears (Ursus arctos), for example, are difficult to study at population scales except with noninvasive data, and NGT via hair trapping informs management over much of grizzly bears’ range. Considerable statistical effort has gone into estimating sources of heterogeneity, but detection error–arising when a visiting bear fails to leave a hair sample–has not been independently estimated. We used camera traps to survey grizzly bear occurrence at fixed hair traps and multi-method hierarchical occupancy models to estimate the probability that a visiting bear actually leaves a hair sample with viable DNA. We surveyed grizzly bears via hair trapping and camera trapping for 8 monthly surveys at 50 (2012) and 76 (2013) sites in the Rocky Mountains of Alberta, Canada. We used multi-method occupancy models to estimate site occupancy, probability of detection, and conditional occupancy at a hair trap. We tested the prediction that detection error in NGT studies could be induced by temporal variability within season, leading to underestimation of occupancy. NGT via hair trapping consistently underestimated grizzly bear occupancy at a site when compared to camera trapping. At best occupancy was underestimated by 50%; at worst, by 95%. Probability of false absence was reduced through successive surveys, but this mainly accounts for error imparted by movement among repeated surveys, not necessarily missed detections by extant bears. The implications of missed detections and biased occupancy estimates for density estimation–which form the crux of management plans–require consideration. We suggest hair-trap NGT studies should estimate and correct detection error using independent survey methods such as cameras, to ensure the reliability of the data upon which species management and conservation actions are based.

Effectiveness and Applications of Hair Traps for the Study of Wild mammal populations

ABSTRACT Direct studies of wild mammals are challenging due to the difficulty for capturing and handling and the associated high costs. Thus, noninvasive hair trapping for surveying mammal populations has been widely used in wildlife ecology and management. However, the efficiency of this method may differ depending on the animal species and other different factors. Here we aimed at evaluating the potential of hair tube traps for reliable detecting mammal species as well as to assess whether type of habitat, baits, hair trap´s size variables (length, diameter and time staying active) and position variables (height, altitude, orientation and location) influenced trapping success (i.e. obtaining hair samples or not) and effectiveness (i.e. percentage of successful sampling traps and the number of species detected) of hair traps. Hair traps were done with PVC tubes with adhesive tape inside, and they were placed at different locations where mammal cues were previously detected. Collected hairs were identifie...

A comparative study of hair trapping by a short grooved surface during conventional and siro-spinning

In this study, theoretical analysis was conducted for hair trapping by a short grooved surface contacting in different distances during conventional and siro-spinning, respectively. Then, blended cotton/ramie conventional and siro yarns were produced without and with the short grooved surface at different position distances. Hairs longer than 3 mm decreased as the surface position distance increased for both conventional and siro spun yarns, reducing short hairs by binding them onto the yarn stem. Conventional yarn hairiness H values decreased gradually as the surface position distance increased; however, siro spun yarn hairiness H values were similar without a gradual decrease as the surface position distance increased. The hair wrapping caused reduction of thin places, and occasional increase of thick places and neps for both conventional and siro yarns spun with the surface, respectively. Unevenness CVm results showed no serious deterioration after applying the surface during conventional and siro-spinning, and even some improved. The experimental results corresponded well to our theoretical analysis.

Field calibration of blowfly-derived DNA against traditional methods for assessing mammal diversity in tropical forests.

Mammal diversity assessments based on DNA derived from invertebrates have been suggested as alternatives to assessments based on traditional methods; however, no study has field-tested both approaches simultaneously. In Peninsular Malaysia, we calibrated the performance of mammal DNA derived from blowflies (Diptera: Calliphoridae) against traditional methods used to detect species. We first compared five methods (cage trapping, mist netting, hair trapping, scat collection, and blowfly-derived DNA) in a forest reserve with no recent reports of megafauna. Blowfly-derived DNA and mist netting detected the joint highest number of species (n = 6). Only one species was detected by multiple methods. Compared to the other methods, blowfly-derived DNA detected both volant and non-volant species. In another forest reserve, rich in megafauna, we calibrated blowfly-derived DNA against camera traps. Blowfly-derived DNA detected more species (n = 11) than camera traps (n = 9), with only one species detected by both methods. The rarefaction curve indicated that blowfly-derived DNA would continue to detect more species with greater sampling effort. With further calibration, blowfly-derived DNA may join the list of traditional field methods. Areas for further investigation include blowfly feeding and dispersal biology, primer biases, and the assembly of a comprehensive and taxonomically-consistent DNA barcode reference library.

Feasibility of using Scent-Baited Hair Traps to Monitor Carnivore Populations in Peninsular Malaysia

Non-invasive genetic sampling is increasingly being used for monitoring mammalian carnivore populations. However, environmental conditions in the tropics challenge researchers' ability to collect samples. We present the results of a preliminary study on the feasibility of using scent-baited hair traps for population monitoring of mammalian carnivores in Peninsular Malaysia. Stations were baited using either fatty acid scent or male cologne applied to hair traps. Video camera traps were also used to monitor carnivore reactions to the scent stations. We recorded 19 visits by seven carnivore species over 764 camera trap nights. Cheek-rubbing and scent-marking behaviour was recorded only for single individuals of two species: the Malayan tiger ( Panthera tigris jacksoni) and clouded leopard ( Neofelis nebulosa). This study suggests that scent-baited hair traps hold some promise for ecological issues requiring DNA analysis in Peninsular Malaysia. Additional research is needed to develop its full potential for conservation monitoring of large carnivores.

Spatiotemporal factors affecting detection of black bears during noninvasive capture–recapture surveys

Abstract Accounting for low and heterogeneous detection probabilities in large mammal capture–recapture sampling designs is a persistent challenge. Our objective was to improve understanding of ecological and biological factors driving detection using multiple data sources from an American black bear ( Ursus americanus ) DNA hair trap study in south-central Missouri. We used Global Positioning System telemetry and remote camera data to examine how a bear’s distance to traps, probability of space use, sex-specific behavior, and temporal sampling frame affect detection probability and number of hair samples collected at hair traps. Regression analysis suggested that bear distance to nearest hair trap was the best predictor of detection probability and indicated that detection probability at encounter was 0.15 and declined to < 0.05 at nearest distances > 330 m from hair traps. From remote camera data, number of hair samples increased with number of visits, but the proportion of hair samples from known visits declined 39% from early June to early August. Bears appeared attracted to lured hair traps from close distances and we recommend a hair trap density of 1 trap/2.6 km 2 with spatial coverage that encompasses potentially large male home ranges. We recommend sampling during the late spring and early summer molting period to increase hair deposition rates.

When the Solution Becomes the Problem

Introduction: Percutaneous Endoscopic Gastrostomy (PEG) tubes are placed for numerous clinical indications. Different endoscopic techniques can be used such as pull method or introducer technique. Common complications include wound infections, tube dysfunction, bleeding, localized pain and gastric outlet obstruction. Introducer technique has been reported to be associated with decreased complications. T-fastener gastropexy is a component of introducer technique. T-fasteners have been shown to obviate the need for emergent replacement after early tube dislodgement. They are expected to fall off about two weeks after placement. We report 3 cases of PEG placement using the introducer technique where the T fasteners caused preventable complications. Report: We report 3 cases of Caucasian men(mean age 69), one with esophageal carcinoma, one with squamous cell carcinoma of the mandible and one with metastatic lung cancer; all of whom were referred for failure to thrive secondary to dysphagia. All underwent 18 French Kimberly-Clark® MIC PEG placement via step dilation method and had 3 T-fasteners placed. All received peri-procedure intravenous third generation cephalosporin. All then presented in about 3-4 weeks post procedure with complications. First patient presented with erythema, fluid drainage and skin ulceration around a T-fastener site with concern for abscess. However, a CT Abdomen did not show any abscess. On evaluation, none of the three fasteners had fallen off. Second patient presented with local erythema and redness around a T- fastener that was still found to be in place. Third patient had significant pain at T-fastener site secondary to hair trapping within the fastener. Adherent T-Fasteners were removed in all patients, and the first two were sent out on short antibiotic courses (first one on oral Augmentin and Ciprofloxacin, second on topical Bactrim). Patients did not develop further complications that required repeat evaluations. Discussion: Variable rates of complications secondary to PEG placement have been reported in literature. Complications can be immediate or delayed. Fasteners ideally fall off in about two weeks after procedure, but can stick and can cause local wound infections, erythema and pain. Some patients can be immunosuppressed and vulnerable to local infections with subsequent systemic progression. Therefore, after reviewing these cases, a policy change was made at our institution. Now patients are instructed to call gastroenterology clinic two weeks post PEG placement and are requested to come in if all T-fasteners have not fallen off. We hope to reduce local wound infections and PEG placement related complications by this simple intervention

Some mechanisms underlying variation in vital rates of grizzly bears on a multiple use landscape

Understanding factors that govern the abundance of organisms is fundamental to the science of ecology and important for conservation and management of species. I used temporal and spatial comparisons to test the influence of human industrial activity, huckleberry (Vaccinium membranaceum) productivity, and population density on grizzly bear (Ursus arctos) vital rates and population trends over a 32-year period. Survival rates of adult and subadult males were 0.84 and 0.78, respectively, and lower than those of adult (0.93) or subadult females (0.96). Of the 31 bears that died while radio-collared, 26 (84%) were killed by people. Of those killed by people, 11 (35%) were legally killed by hunters and 84% were deaths that occurred <120 m from a road. In the first decade of study (1979–1988) when salvage logging and gas exploration was intensive, bear density was relatively low, and huckleberry production was generally good, the population increased (λ = 1.074) with high survival rates of cubs (0.84) and yearlings (0.86) plus a high reproductive rate of 0.374. During the second decade (1989–1998) when there was little industrial activity and huckleberry production remained good, the population continued to grow (λ ≈ 1.06–1.08) because survival of all age classes remained high, but the reproductive rate declined to 0.257. Bear density reached its maximum (55.6 bears/1,000 km2 excluding independent males) at the start of the third decade. During the third decade (1999–2010), there was little industrial activity, but huckleberry production declined dramatically and often completely failed. During the third decade the population declined (λ ≈ 0.955–0.980) as the reproductive rate dropped to 0.192 because of small litters (1.82), extended interbirth intervals (2.93, 3.44, and 4.22 years in decades 1, 2, and 3, respectively) and increased age of primiparity (6.60, 7.09, and 10.46 years in decades 1, 2, and 3, respectively). Adult female survival also declined likely because more females were without offspring and thus vulnerable to hunting. The best model predicting if a parous female would have a small (0 or 1 cub) or large (2 or 3 cub) litter when not encumbered with offspring the previous mating season included both huckleberry abundance the previous year and female bear density. Population inventories during the third decade had approximately twice as many bears detected per DNA hair trap set in the portion of the valley where there had been rapid industrial development, grizzly bear hunting, and large huckleberry fields than in an adjacent portion of the valley that was protected from industry and hunting but with no major huckleberry fields. The abundance of huckleberries growing in mountains above most human activity permitted this population to expand in spite of the industrial development. The population was primarily regulated by the interaction of bear density and the density-independent production of huckleberries, their major summer-fall energy food. © 2015 The Wildlife Society.

In the trap: detectability of fixed hair trap DNA methods in grizzly bear population monitoring

A significant challenge to monitoring wildlife that are secretive, wide ranging, and at low densities is the need to achieve adequate detection rates. Knowledge of spatial patterns in occupancy and the spatial and/or temporal patterns in detectability allows for stratification of traps and improved detection rates. This study investigated how local variation in habitats affected the detectability of grizzly bears in west—central Alberta when monitored with a fixed DNA hair snag design. Bear hair samples were collected in 2011 at 60 sites across 1500 km2 over six sessions, each 14 days in length, between June and August. Microsatellite analysis of hair samples revealed grizzly bear detections at 25 of 60 sites and 21 individual bears. We investigated occupancy and detectability of grizzly bears at the patch and landscape scales using detection histories and program PRESENCE. At the patch scale, grizzly bear detection was highest when sites were placed near streams with clover and in intermediate levels of forest crown closure. At the landscape scale, probability of detection increased near streams and oil and gas wellsites, especially when food resources and wellsite density in the surrounding area was low. Our results highlight the importance of considering local food resources and habitat conditions during placement of fixed DNA hair snag sites. Detectability was not found to vary over time, suggesting that sampling in west—central Alberta can occur at any time between June and August.

A multi-method hierarchical modeling approach to quantifying bias in occupancy from noninvasive genetic tagging studies

Detecting ecological change in mammalian communities requires large volumes of data collected across large landscapes. Noninvasive genetic tagging (NGT) can provide such data and is a common method of estimating species occupancy, distribution, and abundance. Methods to correct errors in genetic analysis exist, but estimating and accounting for detection error in NGT studies—specifically, detection error during hair trapping—has received less attention. If detectability varies with an ecological characteristic that is instead attributed to occupancy, detection error may lead to spurious conclusions. We demonstrate how multi-method occupancy models informed by camera-trapping data can quantify error, partition sources of variability, and estimate occupancy from NGT studies. We surveyed marten (Martes americana), fisher (Pekania pennanti), and wolverine (Gulo gulo) occurrence via hair trapping and camera trapping for 3 repeated monthly surveys at 66 sites in the Rocky Mountains of Alberta, Canada. Camera traps photographed the hair traps and surrounding sampling site. We used multi-method occupancy models to estimate site occupancy, probability of detection, and conditional occupancy at a hair trap. We tested the predictions that detection error in NGT studies could be induced by temporal variability and behavioral variability arising from the presence of heterospecifics. Models indicated that NGT via hair trapping consistently underestimated occupancy of marten, fisher, and wolverine compared to cameras. The magnitude of bias varied, but at worst underestimated occupancy by half. The presence of a heterospecific affected a species' detection at hair traps. Wolverine presence increased marten detection, whereas marten decreased fisher detection at NGT traps. For all species, detection error was reduced through successive monthly surveys, although heterogeneity induced by other mustelids remained. Detection error from multiple sources can bias NGT occupancy estimates, with implications for population estimation, ecological inference, species' legal status assessments, and conservation decisions. We recommend that NGT studies quantify and correct for detection error using independent survey methods and multi-method occupancy models, to improve the ability to answer ecological questions and make conservation decisions in the face of ecological change. © 2014 The Wildlife Society.