Effects of different attractants and human scent on mesocarnivore detection at camera traps

2020 ◽  
Vol 47 (4) ◽  
pp. 338
Author(s):  
Bracy W. Heinlein ◽  
Rachael E. Urbanek ◽  
Colleen Olfenbuttel ◽  
Casey G. Dukes
Keyword(s):  
Fatty Acid ◽  
Castor Oil ◽  
Camera Trap ◽  
Camera Traps ◽  
Individual Species ◽  
Detection Rates ◽  
Capture Success ◽  
Affect Detection ◽  
Species Specific

Abstract ContextCamera traps paired with baits and scented lures can be used to monitor mesocarnivore populations, but not all attractants are equally effective. Several studies have investigated the efficacy of different attractants on the success of luring mesocarnivores to camera traps; fewer studies have examined the effect of human scent at camera traps. AimsWe sought to determine the effects of human scent, four attractants and the interaction between attractants and human scent in luring mesocarnivores to camera traps. Methods We compared the success of synthetic fermented egg (SFE), fatty acid scent (FAS) tablets, castor oil, and sardines against a control of no attractant in luring mesocarnivores to camera traps. We deployed each attractant and the control with either no regard to masking human scent or attempting to restrict human scent for a total of 10 treatments, and replicated treatments eight to nine times in two different phases. We investigated whether: (1) any attractants increased the probability of capturing a mesocarnivore at a camera trap; (2) not masking human scent affected the probability of capturing a mesocarnivore at a camera trap; and (3) any attractants increased the probability of repeat detections at a given camera trap. We also analysed the behaviour (i.e. speed and distance to attractant) of each mesocarnivore in relation to the attractants. Key resultsSardines improved capture success compared with the control treatments, whereas SFE, castor oil, and FAS tablets had no effect when all mesocarnivores were included in the analyses. Masking human scent did not affect detection rates in the multispecies analyses. Individually, the detection of some species depended on the interactions between masking (or not masking) human scent and some attractants. ConclusionsSardines were the most effective as a broad-based attractant for mesocarnivores. Mesocarnivores approached traps baited with sardines at slower rates, which allows for a higher success of capturing an image of the animal. ImplicationsHuman scent may not need to be masked when deploying camera traps for multispecies mesocarnivore studies, but researchers should be aware that individual species respond differently to attractants and may have higher capture success with species-specific attractants.

scholarly journals Long-term monitoring of margays (Leopardus wiedii): Implications for understanding low detection rates

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247536
Author(s):  
Bart J. Harmsen ◽  
Nicola Saville ◽  
Rebecca J. Foster
Keyword(s):  
Detection Rate ◽  
Camera Trap ◽  
Wide Distribution ◽  
Camera Traps ◽  
Detection Rates ◽  
Terrestrial Mammals ◽  
Exclusive Territories ◽  
Carnivore Species ◽  
Density Population

Population assessments of wide-ranging, cryptic, terrestrial mammals rely on camera trap surveys. While camera trapping is a powerful method of detecting presence, it is difficult distinguishing rarity from low detection rate. The margay (Leopardus wiedii) is an example of a species considered rare based on its low detection rates across its range. Although margays have a wide distribution, detection rates with camera traps are universally low; consequently, the species is listed as Near Threatened. Our 12-year camera trap study of margays in protected broadleaf forest in Belize suggests that while margays have low detection rate, they do not seem to be rare, rather that they are difficult to detect with camera traps. We detected a maximum of 187 individuals, all with few or no recaptures over the years (mean = 2.0 captures/individual ± SD 2.1), with two-thirds of individuals detected only once. The few individuals that were recaptured across years exhibited long tenures up to 9 years and were at least 10 years old at their final detection. We detected multiple individuals of both sexes at the same locations during the same survey, suggesting overlapping ranges with non-exclusive territories, providing further evidence of a high-density population. By studying the sparse annual datasets across multiple years, we found evidence of an abundant margay population in the forest of the Cockscomb Basin, which might have been deemed low density and rare, if studied in the short term. We encourage more long-term camera trap studies to assess population status of semi-arboreal carnivore species that have hitherto been considered rare based on low detection rates.

The effect of camera-trap viewshed obstruction on wildlife detection: implications for inference

2020 ◽  
Vol 47 (2) ◽  
pp. 158 ◽  
Author(s):  
Remington J. Moll ◽  
Waldemar Ortiz-Calo ◽  
Jonathon D. Cepek ◽  
Patrick D. Lorch ◽  
Patricia M. Dennis ◽  
...  
Keyword(s):  
Image Data ◽  
Camera Trap ◽  
Camera Traps ◽  
Mammal Species ◽  
Ecological Processes ◽  
Detection Rates ◽  
Management Application ◽  
Efficiency And Effectiveness ◽  
Steep Slopes ◽  
Wildlife Detection

Abstract ContextCamera traps are one of the most popular tools used to study wildlife worldwide. Numerous recent studies have evaluated the efficiency and effectiveness of camera traps as a research tool. Nonetheless, important aspects of camera-trap methodology remain in need of critical investigation. One such issue relates to camera-trap viewshed visibility, which is often compromised in the field by physical obstructions (e.g. trees) or topography (e.g. steep slopes). The loss of visibility due to these obstructions could affect wildlife detection rates, with associated implications for study inference and management application. AimsWe aimed to determine the effect of camera-trap viewshed obstruction on wildlife detection rates for a suite of eight North American species that vary in terms of ecology, commonness and body size. MethodsWe deployed camera traps at 204 sites throughout an extensive semi-urban park system in Cleveland, Ohio, USA, from June to September 2016. At each site, we quantified camera-trap viewshed obstruction by using a cover-board design. We then modelled the effects of obstruction on wildlife detection rates for the eight focal species. Key resultsWe found that detection rates significantly decreased with an increasing viewshed obstruction for five of the eight species, including both larger and smaller mammal species (white-tailed deer, Odocoileus virginianus, and squirrels, Sciurus sp., respectively). The number of detections per week per camera decreased two- to three-fold as visibility at a camera site decreased from completely free of obstruction to mostly obstructed. ConclusionsThese results imply that wildlife detection rates are influenced by site-level viewshed obstruction for a variety of species, and sometimes considerably so. ImplicationsResearchers using camera traps should address the potential for this effect to ensure robust inference from wildlife image data. Accounting for viewshed obstruction is critical when interpreting detection rates as indices of abundance or habitat use because variation in detection rate could be an artefact of site-level viewshed obstruction rather than due to underlying ecological processes.

First photographic records of bush dogs (Speothos venaticus) from camera-traps in Guyana

Mammalia ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Matthew T. Hallett ◽  
Anthony Roberts ◽  
Ashley P. Holland ◽  
Angus Jackman
Keyword(s):  
Camera Trap ◽  
Camera Traps ◽  
Individual Study ◽  
Detection Rates ◽  
Detailed Measurement ◽  
Scale Modelling ◽  
In The Wild ◽  
Bush Dog ◽  
Speothos Venaticus ◽  
Photographic Records

AbstractThe bush dog (Speothos venaticus) is rare, elusive, and difficult to study in the wild. Guyana contains a wealth of intact tropical forest (∼18.4 million ha) and savanna (1.6 million ha) habitats, but management of this species is hindered by a lack of data. We present two photographic records (consisting of nine individuals) of bush dogs from camera-traps set in the Kanuku Mountains Protected Area (KMPA) – the first of this species in Guyana. These records highlight the importance of Guiana Shield forests and Guyana’s expanding protected areas system to the conservation of these wide-ranging carnivores. Additionally, we recommend that detailed measurement and reporting of site variables become standard, as it will improve the efficacy of camera-trap studies of bush dogs and allow for broad-scale modelling of space use not otherwise possible due to the low detection rates at the scale of each individual study.

Quantifying imperfect camera-trap detection probabilities: implications for density modelling

2020 ◽  
Vol 47 (2) ◽  
pp. 177 ◽  
Author(s):  
T. McIntyre ◽  
T. L. Majelantle ◽  
D. J. Slip ◽  
R. G. Harcourt
Keyword(s):  
Population Density ◽  
Surface Temperature ◽  
Ambient Temperature ◽  
Population Level ◽  
Camera Trap ◽  
Camera Traps ◽  
Imperfect Detection ◽  
Detection Rates ◽  
Detection Probabilities ◽  
Density Modelling

Abstract ContextData obtained from camera traps are increasingly used to inform various population-level models. Although acknowledged, imperfect detection probabilities within camera-trap detection zones are rarely taken into account when modelling animal densities. AimsWe aimed to identify parameters influencing camera-trap detection probabilities, and quantify their relative impacts, as well as explore the downstream implications of imperfect detection probabilities on population-density modelling. MethodsWe modelled the relationships between the detection probabilities of a standard camera-trap model (n=35) on a remotely operated animal-shaped soft toy and a series of parameters likely to influence it. These included the distance of animals from camera traps, animal speed, camera-trap deployment height, ambient temperature (as a proxy for background surface temperatures) and animal surface temperature. We then used this detection-probability model to quantify the likely influence of imperfect detection rates on subsequent population-level models, being, in this case, estimates from random encounter density models on a known density simulation. Key resultsDetection probabilities mostly varied predictably in relation to measured parameters, and decreased with an increasing distance from the camera traps and speeds of movement, as well as heights of camera-trap deployments. Increased differences between ambient temperature and animal surface temperature were associated with increased detection probabilities. Importantly, our results showed substantial inter-camera (of the same model) variability in detection probabilities. Resulting model outputs suggested consistent and systematic underestimation of true population densities when not taking imperfect detection probabilities into account. ConclusionsImperfect, and individually variable, detection probabilities inside the detection zones of camera traps can compromise resulting population-density estimates. ImplicationsWe propose a simple calibration approach for individual camera traps before field deployment and encourage researchers to actively estimate individual camera-trap detection performance for inclusion in subsequent modelling approaches.

Searching for rare and secretive snakes: are camera-trap and box-trap methods interchangeable?

2020 ◽  
Vol 47 (6) ◽  
pp. 476 ◽  
Author(s):  
Dalton B. Neuharth ◽  
Wade A. Ryberg ◽  
Connor S. Adams ◽  
Toby J. Hibbitts ◽  
Danielle K. Walkup ◽  
...  
Keyword(s):  
Life Histories ◽  
Detection Rate ◽  
Temporal Trends ◽  
Habitat Type ◽  
Camera Trap ◽  
Camera Traps ◽  
Similar Data ◽  
Detection Rates ◽  
Snake Species ◽  
Snake Detection

Abstract ContextAdvancements in camera-trap technology have provided wildlife researchers with a new technique to better understand their study species. This improved method may be especially useful for many conservation-reliant snake species that can be difficult to detect because of rarity and life histories with secretive behaviours. AimsHere, we report the results of a 6-month camera-trapping study using time lapse-triggered camera traps to detect snakes, in particular the federally listed Louisiana pinesnake (Pituophis ruthveni) in eastern Texas upland forests in the USA. MethodsSo as to evaluate the efficacy of this method of snake detection, we compared camera-trap data with traditional box-trapping data collected over the same time period across a similar habitat type, and with the same goal of detecting P. ruthveni. Key resultsNo differences in focal snake species richness were detected across the trap methods, although the snake-detection rate was nearly three times higher with camera traps than with the box traps. Detection rates of individual snake species varied with the trapping method for all but two species, but temporal trends in detection rates were similar across the trap methods for all but two species. Neither trap method detected P. ruthveni in the present study, but the species has been detected with both trap methods at other sites. ConclusionsThe higher snake-detection rate of the camera-trap method suggests that pairing this method with traditional box traps could increase the detection of P. ruthveni where it occurs. For future monitoring and research on P. ruthveni, and other similarly rare and secretive species of conservation concern, we believe these methods could be used interchangeably by saturating potentially occupied habitats with camera traps initially and then replacing cameras with box traps when the target species is detected. ImplicationsThere are financial and logistical limits to monitoring and researching rare and secretive species with box traps, and those limits are far less restrictive with camera traps. The ability to use camera-trap technologies interchangeably with box-trap methods to collect similar data more efficiently and effectively will have a significant impact on snake conservation.

scholarly journals An approach to rapid processing of camera trap images with minimal human input

2021 ◽  
Author(s):  
Matthew Duggan ◽  
Melissa Groleau ◽  
Ethan Shealy ◽  
Lillian Self ◽  
Taylor Utter ◽  
...  
Keyword(s):  
Science Studies ◽  
Model Building ◽  
Camera Trap ◽  
Camera Traps ◽  
Individual Species ◽  
Building Process ◽  
Transfer Training ◽  
Rapid Processing ◽  
Model Building Process ◽  
Alternative Metrics

Point 1: Camera traps have become an extensively utilized tool in ecological research, but the processing of images created by a network of camera traps rapidly becomes an overwhelming task, even for small networks. Point 2: We used transfer training to create convolutional neural network (CNN) models for identification and classification. By utilizing a small dataset with less than 10,000 labeled images the model was able to distinguish between species and remove false triggers. Point 3: We trained the model to detect 17 object classes with individual species identification, reaching an accuracy of 92%. Previous studies have suggested the need for thousands of images of each object class to reach results comparable to those achieved by human observers; however, we show that such accuracy can be achieved with fewer images. Point 4: Additionally, we suggest several alternative metrics common to computer science studies to accurately evaluate the performance of such camera trap image processing models, as well as methods to adapt the model building process to two targeted purposes.

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

2020 ◽  
Author(s):  
Dacyn Holinda ◽  
Joanna M. Burgar ◽  
A. Cole Burton
Keyword(s):  
Ground Squirrel ◽  
Negative Binomial ◽  
Prey Species ◽  
Camera Trap ◽  
Individual Species ◽  
Gray Wolf ◽  
Mammal Species ◽  
Detection Rates ◽  
Predator Species ◽  
Scent Lures

AbstractCamera 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.

Multiple cameras required to reliably detect feral cats in northern Australian tropical savanna: an evaluation of sampling design when using camera traps

2015 ◽  
Vol 42 (8) ◽  
pp. 642 ◽  
Author(s):  
Danielle Stokeld ◽  
Anke S. K. Frank ◽  
Brydie Hill ◽  
Jenni Low Choy ◽  
Terry Mahney ◽  
...  
Keyword(s):  
Camera Trap ◽  
Camera Traps ◽  
Sampling Effort ◽  
Tropical Savanna ◽  
Northern Australia ◽  
Ecological Data ◽  
Detection Rates ◽  
Feral Cats ◽  
Significant Difference ◽  
Trapping Method

Context Feral cats are a major cause of mammal declines and extinctions in Australia. However, cats are elusive and obtaining reliable ecological data is challenging. Although camera traps are increasingly being used to study feral cats, their successful use in northern Australia has been limited. Aims We evaluated the efficacy of camera-trap sampling designs for detecting cats in the tropical savanna of northern Australia. We aimed to develop a camera-trapping method that would yield detection probabilities adequate for precise occupancy estimates. Methods First, we assessed the influence of two micro-habitat placements and three lure types on camera-trap detection rates of feral cats. Second, using multiple camera traps at each site, we examined the relationship between sampling effort and detection probability by using a multi-method occupancy model. Key results We found no significant difference in detection rates of feral cats using a variety of lures and micro-habitat placement. The mean probability of detecting a cat on one camera during one week of sampling was very low (p = 0.15) and had high uncertainty. However, the probability of detecting a cat on at least one of five cameras deployed concurrently on a site was 48% higher (p = 0.22) and had a greater precision. Conclusions The sampling effort required to achieve detection rates adequate to infer occupancy of feral cats by camera trap is considerably higher in northern Australia than has been observed elsewhere in Australia. Adequate detection of feral cats in the tropical savanna of northern Australia will necessitate inclusion of more camera traps and a longer survey duration. Implications Sampling designs using camera traps need to be rigorously trialled and assessed to optimise detection of the target species for different Australian biomes. A standard approach is suggested for detecting feral cats in northern Australian savannas.

scholarly journals eDNA sampled from stream networks correlates with camera trap detection rates of terrestrial mammals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Arnaud Lyet ◽  
Loïc Pellissier ◽  
Alice Valentini ◽  
Tony Dejean ◽  
Abigail Hehmeyer ◽  
...  
Keyword(s):  
Large Scale ◽  
Stream Water ◽  
Spatial Scales ◽  
Environmental Dna ◽  
Camera Trap ◽  
Camera Traps ◽  
Sufficient Information ◽  
Multiple Time ◽  
Detection Rates ◽  
Terrestrial Mammals

AbstractBiodiversity monitoring delivers vital information to those making conservation decisions. Comprehensively measuring terrestrial biodiversity usually requires costly methods that can rarely be deployed at large spatial scales over multiple time periods, limiting conservation efficiency. Here we investigated the capacity of environmental DNA (eDNA) from stream water samples to survey terrestrial mammal diversity at multiple spatial scales within a large catchment. We compared biodiversity information recovered using an eDNA metabarcoding approach with data from a dense camera trap survey, as well as the sampling costs of both methods. Via the sampling of large volumes of water from the two largest streams that drained the study area, eDNA metabarcoding provided information on the presence and detection probabilities of 35 mammal taxa, 25% more than camera traps and for half the cost. While eDNA metabarcoding had limited capacity to detect felid species and provide individual-level demographic information, it is a cost-efficient method for large-scale monitoring of terrestrial mammals that can offer sufficient information to solve many conservation problems.

scholarly journals Estimating forest antelope population densities using distance sampling with camera traps

Oryx ◽  
2021 ◽  
pp. 1-7
Author(s):  
Rajan Amin ◽  
Hannah Klair ◽  
Tim Wacher ◽  
Constant Ndjassi ◽  
Andrew Fowler ◽  
...  
Keyword(s):  
Survey Methods ◽  
Distance Sampling ◽  
Common Species ◽  
Camera Trap ◽  
Camera Traps ◽  
Individual Species ◽  
Survey Tool ◽  
Terrestrial Mammals ◽  
Detection Probabilities ◽  
The Status

Abstract Traditional transect survey methods for forest antelopes often underestimate density for common species and do not provide sufficient data for rarer species. The use of camera trapping as a survey tool for medium and large terrestrial mammals has become increasingly common, especially in forest habitats. Here, we applied the distance sampling method to images generated from camera-trap surveys in Dja Faunal Reserve, Cameroon, and used an estimate of the proportion of time animals are active to correct for negative bias in the density estimates from the 24-hour camera-trap survey datasets. We also used multiple covariate distance sampling with body weight as a covariate to estimate detection probabilities and densities of rarer species. These methods provide an effective tool for monitoring the status of individual species or a community of forest antelope species, information urgently needed for conservation planning and action.

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