Scent Lures Research Articles

Scent lures and baits at camera traps improve time to first detection and detection probability of two typically elusive species of weasel

AbstractThere is a growing body of evidence that weasel species are in decline globally. More data on their ecology and distribution are needed to plan and justify any conservation management actions. Camera trapping can be an effective survey method for many species; however, the small size and quick movements of weasels present challenges in detection and little consensus exists on practices for attracting them to improve detection. This study tested different combinations of meat baits and scent and audio lures to assess the most effective methods. Camera traps were set up in clusters of three at 42 sites to test the effectiveness of these combinations, accounting for season, in terms of the time to first detection (TFD), detection probability using occupancy models, and the number and clarity of weasel photos. We also repeated TFD and detection probability analyses for setups that were ≥ 20 m apart in case of overlap of effects. The average TFD across all sites was 43 days. Fall typically had the shortest TFD with beaver bait in fall achieving the best results. After accounting for occupancy, predicted detection probability across a 60-day survey was highest in fall with the best combination being salmon lure and beaver bait. The treatment type did not impact the average number of photos captured, but the clarity of photos was significantly positively related to use of bait and lure, type of lure, and specific combinations of bait and lure.

Spatiotemporal partitioning between the endangered San Joaquin kit fox and a novel mesocarnivore community in the urban environment as revealed by camera traps

Urbanization has led to the rapid formation of novel biotic communities, which via interspecific interactions, may affect niche partitioning dynamics of native, sensitive species. The endangered San Joaquin kit fox (Vulpes macrotis mutica; hereafter ‘kit fox’) is a small mesocarnivore inhabiting urban areas of the southern Central Valley of California alongside other urban mesocarnivores. These other species may pose challenges for kit foxes due to a potential lack of evolved mechanisms of defense or avoidance. To address this notion, we evaluated evidence of temporal and spatial partitioning between the kit fox and its potential predators and competitors in an urban environment. We predicted that spatial and temporal overlap would be lower between kit foxes and their predators than with their competitors. We used camera traps with scent lures at high school and college campuses across the southern San Joaquin Valley to monitor the visitation patterns of urban mesocarnivores from 2020 to 2022. We used generalized linear mixed models and AIC model selection to evaluate spatial relationships between kit foxes and other mesocarnivores and we used temporal overlap coefficients and peak activity analysis to evaluate temporal overlap. Kit foxes exhibited low spatial overlap (negative association) with Virginia opossums (Didelphis virginiana) and high spatial overlap (positive association) with domestic cats (Felis catus), domestic dogs (Canis lupus familiaris), northern raccoons (Procyon lotor), and striped skunks (Mephitis mephitis). Kit foxes exhibited low to moderate levels of temporal overlap with other species, the least of which occurring with potential predators (i.e., coyotes (C. latrans), domestic dogs). Our findings support the temporal partitioning and partially support the spatial partitioning hypothesis as potential mechanisms to promote coexistence among mesocarnivores in an urban environment.

An overwinter protocol for detecting wolverines and other carnivores at camera traps paired with automated scent dispensers.

Camera traps deployed with olfactory attractants are used to survey rare and elusive carnivores. Study areas with deep snowpack and rugged terrain present challenges and risks to field personnel, who traditionally must revisit camera stations regularly to refresh attractants. In such locations, alternative overwinter survey protocols that include a persistent attractant would improve both the safety and efficiency of camera-trap surveys. We present a protocol for installing camera traps and automated scent dispensers on trees at above-average maximum snow depth to eliminate the need for interim service visits and to enable standardized surveys to be conducted throughout the year. Our protocol proved to be effective at attracting and detecting numerous and repeated visits by wolverines, fishers, and other carnivores in two montane regions of the western contiguous United States. The volume, timing, and composition of liquid scent lure released by automated scent dispensers can be varied to target multiple species of interest, and the dispenser can be used insituations where bait rewards may influence the behavior of target species and/or pose human safety concerns.

Using decoys and camera traps to estimate depredation rates and neonate survival.

Ungulate neonates-individuals less than four weeks old-typically experience the greatest predation rates, and variation in their survival can influence ungulate population dynamics. Typical methods to measure neonate survival involve capture and radio-tracking of adults and neonates to discover mortality events. This type of fieldwork is invasive and expensive, can bias results if it leads to neonate abandonment, and may still have high uncertainty about the predator species involved. Here we explore the potential for a non-invasive approach to estimate an index for neonate survival using camera traps paired with decoys that mimic white-tailed deer (Odocoileus virginianus) neonates in the first month of life. We monitored sites with camera traps for two weeks before and after the placement of the neonate decoy and urine scent lure. Predator response to the decoy was classified into three categories: did not approach, approached within 2.5 m but did not touch the decoy, or physically touched the decoy; when conducting survival analyses, we considered these second two categories as dead neonates. The majority (76.3%) of the predators approached the decoy, with 51.1% initiating physical contact. Decoy probability of survival was 0.31 (95% CI = 0.22, 0.35) for a 30-day period. Decoys within the geographic range of American black bear (Ursus americanus) were primarily (75%) attacked by bears. Overall, neonate survival probability decreased as predator abundance increased. The camera-decoy protocol required about ½ the effort and 1/3 the budget of traditional capture-track approaches. We conclude that the camera-decoy approach is a cost-effective method to estimate a neonate survival probability index based on depredation probability and identify which predators are most important.

Improving Trapping Efficiency for Control of American Mink (Neovison vison) in Patagonia.

Simple SummaryTwo main challenges to control invasive mammals are to maximize campaign efficacy and cost-effectiveness, and to avoid trapping other species. We designed and tested new protocols to address those challenges to control alien American mink in southern Chile. We recommend the use of the GMV-13 variant of collapsible wire cage with scent gland lure, as they are smaller, cheaper, easier to transport and effective at catching female mink and reducing the possibility of trapping native species. Trapping campaigns using GMV-13 should be conducted principally during summer, with a 200-m trap spacing, for up to 6 days before moving traps to a new site, with a combination of three days with female scent gland lure followed by three days with male scent gland lure. Our modelling reveals that this should result in the removal of at least 70% of the local estimated discrete mink population within the area covered by each transect.Two main challenges when controlling alien American mink (Neovison vison) in Patagonia are to maximize campaign efficacy and cost-effectiveness and to avoid trapping native species. We designed and tested new variants of collapsible wire box traps, compared the efficacy of a food-based bait and a scent lure and compared catch rates in different seasons of the year. We used the data to model the efficiency rate of the trapping and to determine the trapping effort required to remove 70–90% of the estimated discrete mink population. Between January 2018 and March 2021, we operated 59 trapping transects over 103 three-day trapping periods in southern Chile. Traps were first baited with canned fish, and afterwards with mink anal gland lure. We compared the efficacy of mink capture with that of our previous study. We trapped 196 mink (125 males, 71 females), with most captures in summer. The medium-sized GMV-18 trap caught more male mink, but the more compact GMV-13 caught fewer non-target rodents and no native mammals. The scent lure was more successful than the canned fish when the previous campaign’s data were included in the analysis. There was also a significant improvement in the proportion of female mink trapped and reduced labour compared with our previous campaign that used larger traps, fish bait and 400–500 m trap spacings. We caught relatively more females than males after the third night of trapping on a transect. Our data analysis supports the use of the GMV-13 variant of wire cage trap as the best trap size: it is effective on female mink, small, cheap and easy to transport. Combined with mink anal scent lure, it reduces the possibility of trapping native species compared with other traps tested in Chile. As the most efficient method for removing at least 70% of the estimated discrete mink population within the area covered by each trap transect in southern Chile tested to date, we recommend trapping campaigns using GMV-13 during summer, with a 200-m trap spacing, for up to 6 days before moving traps to a new site, with a combination of three days with a female scent gland lure, followed by three days with a male scent gland lure.

The effect of scent lures on detection is not equitable among sympatric species

Context Camera trapping is an effective tool for cost-efficient monitoring of species over large temporal and spatial scales and it is becoming an increasingly popular method for investigating wildlife communities and trophic interactions. However, camera trapping targeting rare and elusive species can be hampered by low detection rates, which can decrease the accuracy and precision of results from common analytical approaches (e.g., occupancy modeling, capture-recapture). Consequently, researchers often employ attractants to increase detection without accounting for how attractants influence detection of species among trophic levels. Aims We aimed to evaluate the influences of a commonly used non-species-specific olfactory lure (i.e. sardines) and sampling design on detection of four species (i.e. bobcat [Lynx rufus], coyote [Canis latrans], raccoon [Procyon lotor], and eastern cottontail [Sylvilagus floridanus]) that represented a range of foraging guilds in an agricultural landscape. Methods We set 180 camera stations, each for ∼28 days, during the summer of 2019. We set cameras with one of three lure treatments: (1) olfactory lure, (2) no olfactory lure, or (3) olfactory lure only during the latter half of the survey. We evaluated the influence of the lure at three temporal scales of detection (i.e. daily probability of detection, independent sequences per daily detection, and triggers per independent sequence). Key results The lure tended to positively influence detection of coyotes and raccoons but negatively influenced detection of bobcats and eastern cottontails. The influence of the lure varied among temporal scales of detection. Conclusions Scent lures can differentially influence detection of species within or among tropic levels, and the influence of a scent lure may vary among temporal scales. Implications Our results demonstrate the importance of evaluating the influence of an attractant for each focal species when using camera data to conduct multi-species or community analyses, accounting for variation in sampling strategies across cameras, and identifying the appropriate species-specific temporal resolution for assessing variation in detection data. Furthermore, we highlight that care should be taken when using camera data as an index of relative abundance (e.g. as is commonly done with prey species) when there is variation in the use of lures across cameras.

Evaluating the efficacy and decay of lures for improving carnivore detections with camera traps

AbstractAbundance and occupancy estimates are essential to wildlife research, but are often hampered by limited detections, especially for cryptic species like carnivores. While scientists can account for limited detections during statistical analyses, increasing detections in the field is the best way to reduce uncertainty. Camera traps are an effective, noninvasive method of monitoring wildlife, and using attractants with camera traps can increase the likelihood of detecting carnivores. We tested two scent lures (sardines and fatty acid tablets) against a control of no lure to determine whether either lure increased detections of six carnivore species, bobcat (Lynx rufus), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), raccoon (Procyon lotor), striped skunk (Memphitis memphitis), and ringtail (Bassariscus astutus). We also examined how detection of carnivores was affected as the lure decayed over time. We used occupancy modeling for each species to determine whether either lure increased detection probability. We then modeled how lure decay affected carnivore detections and determined the optimal length of deployment using generalized linear mixed models. Sardines increased detections across all carnivores, but also had a high rate of decay and were no different than the control at day 18. Fatty acid tablets decayed more slowly, but were not significantly different from the control at any point. Among species, detections of gray foxes and raccoons increased with both sardines and fatty acid tablets, while detections of ringtails increased only with sardines, and other species did not respond significantly to either lure. Our analysis shows that lures can increase detections of carnivores, but species‐specific responses and study objectives must be considered when choosing a lure. These results will allow future researchers to improve the accuracy of abundance and occupancy estimates through increased detections of difficult to study species which ultimately leads to better conservation and management of those species.

Baiting/Luring Improves Detection Probability and Species Identification-A Case Study of Mustelids with Camera Traps.

Simple SummaryCamera traps are now widely used in animal research because they can monitor animals continuously. Nocturnal mammals are particularly difficult to monitor, and identification without cameras would be difficult. However, camera traps can be improved. We here compared two experimental settings to increase detection and images taken of mustelids, mostly martens. Both tuna bait and glandular scents improved the detection and the number of images taken. Both methods were more successful than a control group setting without any attractants.Motion-triggered trail cameras (hereafter camera traps) are powerful tools which are increasingly used in biological research, especially for species inventories or the estimation of species activity. However, camera traps do not always reliably detect animal visits, as a target species might be too fast, too small, or too far away to trigger an image. Therefore, researchers often apply attractants, such as food or glandular scents, to increase the likelihood of capturing animals. Moreover, with attractants, individuals might remain in front of a camera trap for longer periods leading to a higher number of images and enhanced image quality, which in turn might aid in species identification. The current study compared how two commonly used attractants, bait (tuna) and glandular scent (mustelid mix), affected the detection and the number of images taken by camera traps compared to control camera sites with conventional camera traps. We used a before–after control group design, including a baseline. Attractants increased the probability of detecting the target species and number of images. Tuna experiments produced on average 7.25 times as many images per visit than control camera traps, and scent lures produced on average 18.7 times as many images per visit than the control traps.

Evaluation of the Effectiveness of Scented Wooden Posts for DNA Hair Snagging of Brown Bears

Estimating population density and monitoring demographic trends of large carnivores are hard to be done, as they, in general, occur at very low population densities over large ranges and are often elusive. We tested the utility of artificially scented wooden rubbing posts as a tool for DNA hair snagging of brown bears (Ursus arctos), which can be used for noninvasive population monitoring. To determine which type of scents can attract bears, we applied various types of the scent lure [odor of brown bear, α-pinene (turpentine), and wood creosote oil] on wooden posts to compare with an unscented control, using 75 posts in total during 2009–2012. Among them, we confirmed that 23 posts were rubbed by bears at least once. The scent lures were selected as significant variables by a likelihood ratio test. Probability of rubbing by bears was the highest for wooden posts with creosote oil (57.6%). Our study offers a potentially effective means of DNA hair snagging by using artificially scented wooden rubbing posts.

Effects of scent lure on camera trap detections vary across mammalian predator and prey species.

Camera traps are a unique survey tool used to monitor a wide variety of mammal species. Camera trap (CT) data can be used to estimate animal distribution, density, and behaviour. Attractants, such as scent lures, are often used in an effort to increase CT detections; however, the degree which the effects of attractants vary across species is not well understood. We investigated the effects of scent lure on mammal detections by comparing detection rates between 404 lured and 440 unlured CT stations sampled in Alberta, Canada over 120 day survey periods between February and August in 2015 and 2016. We used zero-inflated negative binomial generalized linear mixed models to test the effect of lure on detection rates for a) all mammals, b) six functional groups (all predator species, all prey, large carnivores, small carnivores, small mammals, ungulates), and c) four varied species of management interest (fisher, Pekania pennanti; gray wolf, Canis lupus; moose, Alces alces; and Richardson's ground squirrel; Urocitellus richardsonii). Mammals were detected at 800 of the 844 CTs, with nearly equal numbers of total detections at CTs with (7110) and without (7530) lure, and variable effects of lure on groups and individual species. Scent lure significantly increased detections of predators as a group, including large and small carnivore sub-groups and fisher specifically, but not of gray wolf. There was no effect of scent lure on detections of prey species, including the small mammal and ungulate sub-groups and moose and Richardson's ground squirrel specifically. We recommend that researchers explicitly consider the variable effects of scent lure on CT detections across species when designing, interpreting, or comparing multi-species surveys. Additional research is needed to further quantify variation in species responses to scent lures and other attractants, and to elucidate the effect of attractants on community-level inferences from camera trap surveys.

Evaluation of Novel Trapping Lures for Monitoring Exotic and Native Container-Inhabiting Aedes spp. (Diptera: Culicidae) Mosquitoes.

Surveillance for diurnal container-inhabiting mosquitoes such as Aedes albopictus (Skuse), Aedes japonicus japonicus (Theobald), and Aedes triseriatus (Say) have routinely relied on the deployment of multiple trap types, including CO2-baited light traps, gravid traps, oviposition traps, and BG-Sentinel. These trap configurations have met with varying degrees of effectiveness and in many instances likely under-sample these key mosquito vectors. Most recently, the BG-Sentinel trap used in conjunction with the human-scent lure has been largely accepted as the gold-standard for monitoring Ae. albopictus. However, its ability to attract other container-inhabiting Aedes species has not been fully evaluated. During 2018, we tested new scent lures, TrapTech Lure-A and Lure-H (Bedoukian Research, Inc.), using BG-Sentinel traps with CO2 in two regions of Connecticut, Stamford and Hamden, against the BG-Lure. Pooled mosquitoes were additionally screened for arbovirus infection. A total of 47,734 mosquitoes representing 8 genera and 32 species were captured during the study, with the Stamford site deriving on average three times as many mosquitoes per trap, adjusting for sampling effort. Lure-A and Lure-H outperformed the BG-Lure in terms of total numbers, diversity evenness, and the proportion of both Ae. j. japonicus and Ae. triseriatus. There were no significant differences among lures in capturing Ae. albopictus, and in terms of species richness. Fifty-seven isolates of virus (West Nile, Jamestown Canyon, and La Crosse viruses) were obtained during the study, with no significant difference between trap-lure. We highlight both novel lures as effective attractants for use in mosquito surveillance=, which either outperform, or equal, BG-Lure.

Which moths might be pollinators? Approaches in the search for the flower‐visiting needles in the Lepidopteran haystack

1. The natural history of pollination has been studied for centuries and is well documented for diurnal insect species, such as bees and butterflies, but less so for moths. There are notable cases of pollination systems among moths, but given their enormous diversity and primarily nocturnal habits, the role of moths as flower visitors is poorly understood. One potential issue with studying moth‐pollination systems is determining which approach to use in order to acquire data and reveal pollination patterns and dynamics. Based on reports from the literature and the authors' own research, this paper outlines eight approaches that can be employed to search for patterns of flower visitation by moths.2. The outlined approaches include searching the internet and online databases, sampling ecosystems, monitoring specific flowers, using artificial baits and floral scent lures, using moth phylogeny, proboscis morphology, and DNA and environmental DNA metabarcoding, which are supplemented with a brief description of the techniques and examples for each approach.3. Each approach has the potential to increase researchers' knowledge of associations between moths and the flowers that they visit, but their relative strengths and limitations are dependent on scope, efficacy of application, technical expertise, and level of effort.4. Each of these approaches, alone or in combination, are likely to be useful in the search for novel information on the natural history of flower visitation by moths and other potential pollinators.

Maximising camera trap data: Using attractants to improve detection of elusive species in multi-species surveys.

Camera traps are a key tool in ecological studies, and are increasingly being used to understand entire communities. However, robust inferences continue to be hampered by low detection of rare and elusive species. Attractants can be used to increase detection rates, but may also alter behaviour, and little research has evaluated short-term, localized response to the presence of attractants. We conducted three camera trap surveys in Kibale National Park, Uganda, using food baits and scent lures (“attractants”) at each camera station to entice small carnivores to pass in front of camera stations. To examine the interrelationship between scavenging and response to attractants, we also placed camera traps at five food refuse pits. We modelled the effect of attractant and duration of trap placement on the detection probability of small carnivores and selected African golden cat Caracal aurata prey items. We examine transient site response of each species, by comparing our observed likelihood of detection in each 24 h period from 1–7 d following refreshing of attractants to randomly generated capture histories. African civet Civettictis civetta, rusty-spotted genet Genetta maculata, African palm civet Nandinia binotata, and marsh mongoose Atilax paludinosus detection probabilities were highest and Weyns’s red duiker Cephalophus wenysi detection probability was lowest immediately after attractants were placed. Within 24 h after attractant was placed, rusty-spotted genet and African palm civet were more likely to be detected and African golden cat, red duiker, and blue duiker Philantomba monticola were less likely to be detected. Our results suggest that attractants can increase detection of small-bodied species and include some arboreal species in terrestrial camera trap sampling. However, attractants may also alter short-term visitation rates of some species, with potentially cascading effects on others. Community level and intraguild interaction studies should control for the potentially confounding effects of attractants on spatial activity patterns.

Synthetic Ligands of Olfactory Binding Proteins Modulate Aggregation Response of Asian Citrus Psyllid in the Presence of Host-Plant Volatiles.

There is interest in using ligands of chemosensory binding proteins (CBP) to augment an insect’s responsiveness to chemosensory cues. We showed previously that combining a synthetic ligand of a CBP with limonene, a common citrus volatile, enhanced the probing response of Asian citrus psyllid (Diaphorina citri). Here, we determined whether synthetic compounds, which were ligands of D. citri olfactory binding protein (OBP) DCSAP4, influenced the settling and aggregation levels of psyllids on young citrus shoots. The test ligands and Cmac scent were dispensed from a droplet of an emulsified wax product (SPLAT) placed on the bottom of each vial. The shoots were presented: (1) alone (shoot + blank SPLAT), (2) with a mixture of citrus volatiles (“Cmac scent”) (shoot + SPLAT with Cmac scent), or (3) with different concentrations of test ligands (shoot + SPLAT with test ligand at concentration 1, shoot + SPLAT with test ligand at concentration 2, etc.). Depending on the availability of test ligands, sprigs, and psyllids, each test included from two to four replicates of each treatment (i.e., shoot only, shoot + Cmac scent, shoot + test ligand at concentration 1, shoot + test ligand at concentration 2, etc.); only a single test ligand was presented in each test. For each test, 200 D. citri were released in the test area and the numbers of psyllids on each sprig were counted 24 h later. Sprigs with ≥7 psyllids were considered to be an aggregation. A total of seven ligands were tested individually. Four of the ligands (654, 717, 784, and 861) modulated psyllid settling and aggregation response, causing greater settling and aggregation to sprigs presented with the Cmac scent than to those sprigs with blank SPLAT. Presentation of one of the ligands (019) resulted in an opposite effect in which psyllid settling and aggregation levels were lower on sprigs with Cmac scent than on those with blank SPLAT. There were no differences in settling levels in the different treatment vials in the Ligand 905 experiment. In the Ligand 937 experiment, settling levels did not vary significantly between treatment vials although settling levels were relatively high in all treatment vials and there was a significant treatment effect. Increased settling and aggregation levels were largely not observed with in the vials with only the test ligands, and there was little effect of ligand concentration on psyllid response levels. This suggests that the test ligands themselves did not attract the psyllids but rather modulated the psyllid’s response to the Cmac scent. The results suggest that synthetic ligands of D. citri CBPs can be used to increase the effectiveness of citrus scent lures used to attract psyllids to monitoring traps and attract and kill devices.

Identification of 2-phenylethanol with a rose-like odor from anal sac secretions of the small Indian mongoose (Herpestes auropunctatus).

The small Indian mongoose (Herpestes auropunctatus) is an invasive species in Okinawa and Amami-Oshima, Japan. Major strategies for their eradication have been the use of baited traps, which suffer from decreasing efficiency with declining populations and the bycatch of native animals. To address these concerns, mongoose-specific lures are required. In this study, we aimed to identify species- and/or sex-specific compounds from anal sac secretions of small Indian mongooses. Volatile compounds emitted from male and female mongoose anal sac secretions were analyzed by thermal desorption-gas chromatography-mass spectrometry. In addition to several fatty acids, 2-phenylethanol was identified as a minor compound, which is uncommon in mammalian secretions but a dominant odorant in roses. Female samples emitted higher levels of 2-phenylethanol than male samples did. These findings indicate that 2-phenylethanol is a female-specific volatile compound of anal sac secretions in small Indian mongooses, and it may be useful as an ingredient of mongoose-specific scent lures.

Improving mesocarnivore detectability with lures in camera-trapping studies

Context Camera trapping is commonly employed for studying carnivores because it provides better data than do other methods, and with lower costs. Increasing the probability of detecting the target species can reduce parameter uncertainty and survey effort required to estimate density and occurrence. Different methods, including attractants and baits, can be used to increase detectability. However, their efficacy has rarely been quantitatively assessed. Aims To quantify the efficacy of scent and bait attractants to increase the detection probability of mesocarnivores by camera trapping. Methods We tested two scent lures, valerian extract (Val) and lynx urine (LU), their combination (Val–LU), and a non-reward bait (i.e. not accessible to the animal), raw chicken, as carnivore attractants in two protected areas of central Spain. We used camera-trapping records under an occupancy-modelling framework to estimate attractant-specific detection probabilities for six mesocarnivore species, and quantified their effects by comparing these estimates with the baseline (i.e. no attractant) detectability. Key results The weekly detection probability of four mesocarnivore species (red fox, Vulpes vulpes, stone marten, Martes foina, common genet, Genetta genetta, and Eurasian badger, Meles meles) significantly increased when Val–LU (between 0.11 ± 0.07 and 0.67 ± 0.05) or chicken (between 0.31 ± 0.02 and 0.77 ± 0.22) were used as attractant, when compared with baseline detectability (between 0.01 ± 0.02 and 0.29 ± 0.05). Although rarely, wildcats (Felis silvestris) were mostly detected with Val–LU. The probability of detecting a species after k sampling occasions (7 days each) where it was present was highly improved with both Val–LU and chicken for all species (e.g. from 0.20 to 0.98 after four sampling occasions with chicken for the stone marten). Both attractants reduced the sampling time required to ascertain that a species was absent to between 42% and 15% of baseline values. Conclusions The tested attractants greatly improved the detectability of most Iberian mesocarnivores. Although chicken was preferable for some species such as stone marten, Val–LU is most efficient for detecting the whole mesocarnivore community, including rare species such as wildcats. Implications Attractant selection in studies using non-invasive detection methods must be supported by quantitative assessment of the detection probability associated to each attractant. Researchers must choose those attractants best fitting target species and study aims.

Assessment of Attractants for Neotropical Mammals

Mammals play important ecological roles in tropical regions but are difficult to study due to discrete habits, low population densities, and large home ranges. Thus, the use of attractive substances has frequently been adopted to quantify the distribution and abundance of elusive mammals. However, the insight generated from studies using attractants is often limited by a lack of methodological standardization. To inform the use of attractants in the Neotropics, we reviewed 30 years of the scientific literature that used some type of attractant in mammal studies. From a total of 60 studies, the majority (65%) did not use any control (or pseudocontrol) in their sampling design and only 40% used some statistical test to explicitly evaluate the efficiency of the attractant used. A wide range of edible (animal or vegetal origin) and inedible substances (e.g., scent lures) were used alone or in combination and the effects differed greatly among orders and species. Most studies (67%) targeted or registered carnivores, and this order had the largest number of substances (edible and inedible) used across all studies. There seems to be only a consensus in the use and attraction effect with frugivorous bats (Phyllostomidae) with fruits, essential oils, and floral compounds. The lack of standardization of use of attractants in mammal studies undermines the comparability of results among studies. We conclude with some general guidelines to maximize comparability among studies and to enhance the potential usefulness of the use of attractants for mammals.

Detection of Iberian terrestrial mammals employing olfactory, visual and auditory attractants

Whereas high lure specificity for mammal monitoring is often sought, little effort has been put into identifying general-purpose attractants for multispecies mammal surveys. We examined whether the olfactory lures ‘fatty acid scent’ (FAS) and catnip oil differ in their ability to detect Iberian larger mammals (body mass > 800 g, i.e. lagomorphs, ungulates and most carnivores); whether the addition of visual and acoustic stimuli increases detection efficiency; and whether environmental variables interact with lures to influence detection. Three treatments were randomly assigned to 192 detection plots: olfactory lures only, visual lures (a combination of olfactory and visual stimuli) and auditory lures (all three types of stimuli). The design was balanced across two detection methods and three landscapes. Out of 13 target species, two were absent in the study plots and six (three common and three rare species) were detected with low frequency. The two olfactory attractants produced similar detection rates for species allowing analysis. The addition of visual and auditory stimuli did not increase detection and apparently induced repulsion for some species. Environmental variables associated with scent diffusion and lure visibility did not significantly influence mammal detection. Monitoring of mammal communities over large areas may gain efficiency by selecting lures that are simple, have a constant chemical composition, require short handling times and allow detection of all occurring species. A single olfactory attractant (FAS) could be suitable for designing large-scale monitoring programmes at least for five common mammal species, provided that passive detection methods and lure use are chosen.

THE RESULTS OF THE STUDY OF THE BROWN BEAR POPULATION IN THE RUSSIAN PART OF THE PASVIK-INARI TRILATERAL PARK ACCORDING TO DNA ANALYSIS AND DATA FROM CAMERA TRAPS

In framework of an international project of brown bear population monitoring, the bear population size and structure were analyzed on the Russian side of the Pasvik-Inari Trilateral Park (Russia, Norway, Finland) in 2015. The paper presents data gathered by two noninvasive methods: DNA analysis of hair samples and feces and the camera traps method. The material was obtained with 5 hair traps of made of barbed wire and scent lure and 4 Boskon Guard camera traps. In addition, feces were collected, as well as hair samples from national border fencing by staff of the Russian Border Authority. In total, 54 hair samples and 10 feces samples were collected. On the basis of the results the brown bear population size was estimated at 20 individuals in the study area: 13 individuals were detected by DNA analysis only, the remaining 7 animals – with the help of camera traps. The records include 9 females and 7 males; 13 adults, 4 yearlings and 3 cubs. The social structure consisted of three family groups, 10 singles, including 1 possible dominant male. Average brown bear density was 100 animals/1000 km². The combined usage of hair and feces collection, camera traps and GIS proved the techniques to be complementary in the analysis of the size and structure of the brown bear population.

Olfactory attractants and parity affect prenatal androgens and territoriality of coyote breeding pairs

Hormones are fundamental mediators of personality traits intimately linked with reproductive success. Hence, alterations to endocrine factors may dramatically affect individual behavior that has subsequent fitness consequences. Yet it is unclear how hormonal or behavioral traits change with environmental stressors or over multiple reproductive opportunities, particularly for biparental fauna. To simulate an environmental stressor, we exposed captive coyote (Canis latrans) pairs to novel coyote odor attractants (i.e. commercial scent lures) mid-gestation to influence territorial behaviors, fecal glucocorticoid (FGMs) and fecal androgen metabolites (FAMs). In addition, we observed coyote pairs as first-time and experienced breeders to assess the influence of parity on our measures. Treatment pairs received the odors four times over a 20-day period, while control pairs received water. Odor-treated pairs scent-marked (e.g. urinated, ground scratched) and investigated odors more frequently than control pairs, and had higher FAMs when odors were provided. Pairs had higher FAMs as first-time versus experienced breeders, indicating that parity also affected androgen production during gestation. Moreover, repeatability in scent-marking behaviors corresponded with FGMs and FAMs, implying that coyote territoriality during gestation is underpinned by individually-specific hormone profiles. Our results suggest coyote androgens during gestation are sensitive to conspecific olfactory stimuli and prior breeding experience. Consequently, fluctuations in social or other environmental stimuli as well as increasing parity may acutely affect coyote traits essential to reproductive success.