Influence of camera-trap sampling design on mammal species capture rates and community structures in southeastern Brazil

The distribution of species and population attributes are critical data for biodiversity conservation. As a tool for obtaining such data, camera traps have become increasingly common throughout the world. However, there are disagreements on how camera-trap records should be used due to imperfect species detectability and limitations regarding the use of capture rates as surrogates for abundance. We evaluated variations in the capture rates and community structures of mammals in camera-trap surveys using four different sampling designs. The camera traps were installed on internal roads (in the first and fourth years of the study), at 100-200 m from roads (internal edges; second year) and at 500 m from the nearest internal road (forest interior; third year). The mammal communities sampled in the internal edges and forest interior were similar to each other but differed significantly from those sampled on the roads. Furthermore, for most species, the number of records and the capture success varied widely among the four sampling designs. A further experiment showed that camera traps placed on the same tree trunk but facing in opposing directions also recorded few species in common. Our results demonstrated that presence or non-detection and capture rates vary among the different sampling designs. These differences resulted mostly from the habitat use and behavioral attributes of species in association with differences in sampling surveys, which resulted in differential detectability. We also recorded variations in the distribution of records per sampling point and at the same spot, evidencing the stochasticity associated with the camera-trap location and orientation. These findings reinforce that for species whose specimens cannot be individually identified, the capture rates should be best used as inputs for presence and detection analyses and for behavior inferences (regarding the preferential use of habitats and activity patterns, for example). Comparisons between capture rates or among relative abundance indices, even for the same species, should be made cautiously.

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A sparse observation model to quantify species interactions in time and space

10.1101/815027 ◽

2019 ◽

Author(s):

Sadoune Ait Kaci Azzou ◽

Liam Singer ◽

Thierry Aebischer ◽

Madleina Caduff ◽

Beat Wolf ◽

...

Keyword(s):

Species Interactions ◽

Activity Patterns ◽

Niche Partitioning ◽

Camera Trap ◽

Camera Traps ◽

Observation Model ◽

Occupancy Models ◽

Time And Space ◽

Imperfect Detection ◽

Mobile Species

SummaryCamera traps and acoustic recording devices are essential tools to quantify the distribution, abundance and behavior of mobile species. Varying detection probabilities among device locations must be accounted for when analyzing such data, which is generally done using occupancy models. We introduce a Bayesian Time-dependent Observation Model for Camera Trap data (Tomcat), suited to estimate relative event densities in space and time. Tomcat allows to learn about the environmental requirements and daily activity patterns of species while accounting for imperfect detection. It further implements a sparse model that deals well will a large number of potentially highly correlated environmental variables. By integrating both spatial and temporal information, we extend the notation of overlap coefficient between species to time and space to study niche partitioning. We illustrate the power of Tomcat through an application to camera trap data of eight sympatrically occurring duiker Cephalophinae species in the savanna - rainforest ecotone in the Central African Republic and show that most species pairs show little overlap. Exceptions are those for which one species is very rare, likely as a result of direct competition.

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Use of highway culverts by the water opossum (Chironectes minimus) in southeastern Brazil

Biota Neotropica ◽

10.1590/1676-0611-bn-2020-1058 ◽

2020 ◽

Vol 20 (4) ◽

Author(s):

Paula Ribeiro Prist ◽

Guilherme S. T. Garbino ◽

Fernanda Delborgo Abra ◽

Thais Pagotto ◽

Osnir Ormon Giacon

Keyword(s):

New Records ◽

Camera Trap ◽

Sao Paulo ◽

Riparian Forests ◽

Camera Traps ◽

Southeastern Brazil ◽

São Paulo ◽

Aquatic Mammal ◽

Paulo State ◽

Degraded Area

Abstract The water opossum (Chironectes minimus) is a semi-aquatic mammal that is infrequently sampled in Atlantic rainforest areas in Brazil. Here we report on new records of C. minimus in the state of São Paulo, southeastern Brazil, and comment on its behavior and ecology. We placed nine camera traps in culverts and cattle boxes under a highway, between 2017 and 2019. From a total of 6,750 camera-trap-days, we obtained 16 records of C. minimus (0.24 records/100 camera-trap-days) in two cameras placed in culverts over streams. Most of the records were made between May and August, in the dry season and in the first six hours after sunset. The new records are from a highly degraded area with some riparian forests. The records lie approximately 30 km away from the nearest protected area where the species is known to occur. We suggest that C. minimus has some tolerance to degraded habitats, as long as the water bodies and riparian forests are minimally preserved. The new records presented here also fill a distribution gap in western São Paulo state.

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Spot on: using camera traps to individually monitor one of the world’s largest lizards

Wildlife Research ◽

10.1071/wr19159 ◽

2020 ◽

Vol 47 (4) ◽

pp. 326 ◽

Cited By ~ 1

Author(s):

Harry A. Moore ◽

Jacob L. Champney ◽

Judy A. Dunlop ◽

Leonie E. Valentine ◽

Dale G. Nimmo

Keyword(s):

Activity Patterns ◽

Image Data ◽

Dorsal Surface ◽

Camera Trap ◽

Camera Traps ◽

Identification Accuracy ◽

Individual Identification ◽

Lizard Species ◽

Late Afternoon ◽

Large Animals

Abstract ContextEstimating animal abundance often relies on being able to identify individuals; however, this can be challenging, especially when applied to large animals that are difficult to trap and handle. Camera traps have provided a non-invasive alternative by using natural markings to individually identify animals within image data. Although camera traps have been used to individually identify mammals, they are yet to be widely applied to other taxa, such as reptiles. AimsWe assessed the capacity of camera traps to provide images that allow for individual identification of the world’s fourth-largest lizard species, the perentie (Varanus giganteus), and demonstrate other basic morphological and behavioural data that can be gleaned from camera-trap images. MethodsVertically orientated cameras were deployed at 115 sites across a 10000km2 area in north-western Australia for an average of 216 days. We used spot patterning located on the dorsal surface of perenties to identify individuals from camera-trap imagery, with the assistance of freely available spot ID software. We also measured snout-to-vent length (SVL) by using image-analysis software, and collected image time-stamp data to analyse temporal activity patterns. ResultsNinety-two individuals were identified, and individuals were recorded moving distances of up to 1975m. Confidence in identification accuracy was generally high (91%), and estimated SVL measurements varied by an average of 6.7% (min=1.8%, max=21.3%) of individual SVL averages. Larger perenties (SVL of >45cm) were detected mostly between dawn and noon, and in the late afternoon and early evening, whereas small perenties (SVL of <30cm) were rarely recorded in the evening. ConclusionsCamera traps can be used to individually identify large reptiles with unique markings, and can also provide data on movement, morphology and temporal activity. Accounting for uneven substrates under cameras could improve the accuracy of morphological estimates. Given that camera traps struggle to detect small, nocturnal reptiles, further research is required to examine whether cameras miss smaller individuals in the late afternoon and evening. ImplicationsCamera traps are increasingly being used to monitor reptile species. The ability to individually identify animals provides another tool for herpetological research worldwide.

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Daily Activity Patterns and Co-Occurrence of Duikers Revealed by an Intensive Camera Trap Survey across Central African Rainforests

Animals ◽

10.3390/ani10122200 ◽

2020 ◽

Vol 10 (12) ◽

pp. 2200

Author(s):

Fructueux G. A. Houngbégnon ◽

Daniel Cornelis ◽

Cédric Vermeulen ◽

Bonaventure Sonké ◽

Stephan Ntie ◽

...

Keyword(s):

Daily Activity ◽

Activity Patterns ◽

Camera Trap ◽

Camera Traps ◽

The Other ◽

Species Pairs ◽

Free Ranging ◽

First Time ◽

Daily Activity Patterns ◽

Temporal Overlap

The duiker community in Central African rainforests includes a diversity of species that can coexist in the same area. The study of their activity patterns is needed to better understand habitat use or association between the species. Using camera traps, we studied the temporal activity patterns, and quantified for the first time the temporal overlap and spatial co-occurrence between species. Our results show that: (i) Two species are strongly diurnal: Cephalophus leucogaster, and Philantomba congica, (ii) two species are mostly diurnal: C.callipygus and C. nigrifrons, (iii) one species is strongly nocturnal: C.castaneus, (iv) and one species is mostly nocturnal: C.silvicultor. Analyses of temporal activities (for five species) identified four species pairs that highly overlapped (Δ^≥ 0.80), and six pairs that weakly overlapped (Δ^ between 0.06 and 0.35). Finally, co-occurrence tests reveal a truly random co-occurrence (plt > 0.05 and pgt > 0.05) for six species pairs, and a positive co-occurrence (pgt < 0.05) for four pairs. Positive co-occurrences are particularly noted for pairs formed by C.callipygus with the other species (except C. nigrifrons). These results are essential for a better understanding of the coexistence of duikers and the ecology of poorly known species (C. leucogaster and C. nigrifrons), and provide clarification on the activity patterns of C. silvicultor which was subject to controversy. Camera traps proved then to be a powerful tool for studying the activity patterns of free-ranging duiker populations.

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

Wildlife Research ◽

10.1071/wr19004 ◽

2020 ◽

Vol 47 (2) ◽

pp. 158 ◽

Cited By ~ 1

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.

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Differences in activity patterns of the Neotropical otter Lontra longicaudis between rivers of two Brazilian ecoregions

Journal of Tropical Ecology ◽

10.1017/s0266467416000079 ◽

2016 ◽

Vol 32 (2) ◽

pp. 170-174 ◽

Cited By ~ 11

Author(s):

Marcelo Lopes Rheingantz ◽

Caroline Leuchtenberger ◽

Carlos André Zucco ◽

Fernando A.S. Fernandez

Keyword(s):

Atlantic Forest ◽

Human Activity ◽

Activity Patterns ◽

Kernel Density ◽

Camera Trap ◽

Camera Traps ◽

Use Of Time ◽

Activity Behaviour ◽

Lontra Longicaudis

Abstract:Circadian use of time is an important, but often neglected, part of an animal's niche. We compared the activity patterns of the Neotropical otter Lontra longicaudis in two different areas in Brazil using camera traps placed at the entrance of holts. We obtained 58 independent photos in the Atlantic Forest (273 camera trap-days) and 46 photos in Pantanal (300 camera trap-days). We observed different kernel density probabilities on these two areas (45.6% and 14.1% overlap between the 95% and 50% density isopleths respectively). We observed the plasticity in Neotropical otter activity behaviour with different activity patterns in the two areas. In the Pantanal, the Neotropical otter selected daylight (Ivlev = 0.23) and avoided night (Ivlev = −0.44), while in the Atlantic Forest it selected dawn (Ivlev = 0.24) and night (Ivlev = 0.14), avoiding daylight (Ivlev = −0.33). We believe that this pattern can be due to human activity or shifts in prey activity.

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How to snap your cat: optimum lures and their placement for attracting mammalian predators in arid Australia

Wildlife Research ◽

10.1071/wr14193 ◽

2015 ◽

Vol 42 (1) ◽

pp. 1 ◽

Cited By ~ 23

Author(s):

J. L. Read ◽

A. J. Bengsen ◽

P. D. Meek ◽

K. E. Moseby

Keyword(s):

Arid Zone ◽

Activity Patterns ◽

Capture Rate ◽

Camera Trap ◽

Camera Traps ◽

Monitoring And Control ◽

Feral Cats ◽

Behavioural Responses ◽

Visitation Rates ◽

And Control

Context Automatically activated cameras (camera traps) and automated poison-delivery devices are increasingly being used to monitor and manage predators such as felids and canids. Maximising visitation rates to sentry positions enhances the efficacy of feral-predator management, especially for feral cats, which are typically less attracted to food-based lures than canids. Aims The influence of camera-trap placement and lures were investigated to determine optimal monitoring and control strategies for feral cats and other predators in two regions of semi-arid South Australia. Methods We compared autumn and winter capture rates, activity patterns and behaviours of cats, foxes and dingoes at different landscape elements and with different lures in three independent 6 km × 3 km grids of 18 camera-trap sites. Key results Neither visual, olfactory or audio lures increased recorded visitation rates by any predators, although an audio and a scent-based lure both elicited behavioural responses in predators. Cameras set on roads yielded an eight times greater capture rate for dingoes than did off-road cameras. Roads and resource points also yielded highest captures of cats and foxes. All predators were less nocturnal in winter than in autumn and fox detections at the Immarna site peaked in months when dingo and cat activity were lowest. Conclusions Monitoring and management programs for cats and other predators in arid Australia should focus on roads and resource points where predator activity is highest. Olfactory and auditory lures can elicit behavioural responses that render cats more susceptible to passive monitoring and control techniques. Dingo activity appeared to be inversely related to fox but not cat activity during our monitoring period. Implications Optimised management of feral cats in the Australian arid zone would benefit from site- and season-specific lure trials.

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Efficient Pipeline for Automating Species ID in new Camera Trap Projects

Biodiversity Information Science and Standards ◽

10.3897/biss.3.37222 ◽

2019 ◽

Vol 3 ◽

Author(s):

Sara Beery ◽

Dan Morris ◽

Siyu Yang ◽

Marcel Simon ◽

Arash Norouzzadeh ◽

...

Keyword(s):

Machine Learning ◽

Image Annotation ◽

Activity Patterns ◽

Camera Trap ◽

Camera Traps ◽

High Rate ◽

Species Classification ◽

Data Set ◽

Training Time ◽

Animal Populations

Camera traps are heat- or motion-activated cameras placed in the wild to monitor and investigate animal populations and behavior. They are used to locate threatened species, identify important habitats, monitor sites of interest, and analyze wildlife activity patterns. At present, the time required to manually review images severely limits productivity. Additionally, ~70% of camera trap images are empty, due to a high rate of false triggers. Previous work has shown good results on automated species classification in camera trap data (Norouzzadeh et al. 2018), but further analysis has shown that these results do not generalize to new cameras or new geographic regions (Beery et al. 2018). Additionally, these models will fail to recognize any species they were not trained on. In theory, it is possible to re-train an existing model in order to add missing species, but in practice, this is quite difficult and requires just as much machine learning expertise as training models from scratch. Consequently, very few organizations have successfully deployed machine learning tools for accelerating camera trap image annotation. We propose a different approach to applying machine learning to camera trap projects, combining a generalizable detector with project-specific classifiers. We have trained an animal detector that is able to find and localize (but not identify) animals, even species not seen during training, in diverse ecosystems worldwide. See Fig. 1 for examples of the detector run over camera trap data covering a diverse set of regions and species, unseen at training time. By first finding and localizing animals, we are able to: drastically reduce the time spent filtering empty images, and dramatically simplify the process of training species classifiers, because we can crop images to individual animals (and thus classifiers need only worry about animal pixels, not background pixels). drastically reduce the time spent filtering empty images, and dramatically simplify the process of training species classifiers, because we can crop images to individual animals (and thus classifiers need only worry about animal pixels, not background pixels). With this detector model as a powerful new tool, we have established a modular pipeline for on-boarding new organizations and building project-specific image processing systems. We break our pipeline into four stages: 1. Data ingestion First we transfer images to the cloud, either by uploading to a drop point or by mailing an external hard drive. Data comes in a variety of formats; we convert each data set to the COCO-Camera Traps format, i.e. we create a Javascript Object Notation (JSON) file that encodes the annotations and the image locations within the organization’s file structure. 2. Animal detection We next run our (generic) animal detector on all the images to locate animals. We have developed an infrastructure for efficiently running this detector on millions of images, dividing the load over multiple nodes. We find that a single detector works for a broad range of regions and species. If the detection results (as validated by the organization) are not sufficiently accurate, it is possible to collect annotations for a small set of their images and fine-tune the detector. Typically these annotations would be fed back into a new version of the general detector, improving results for subsequent projects. 3. Species classification Using species labels provided by the organization, we train a (project-specific) classifier on the cropped-out animals. 4. Applying the system to new data We use the general detector and the project-specific classifier to power tools facilitating accelerated verification and image review, e.g. visualizing the detections, selecting images for review based on model confidence, etc. The aim of this presentation is to present a new approach to structuring camera trap projects, and to formalize discussion around the steps that are required to successfully apply machine learning to camera trap images. The work we present is available at http://github.com/microsoft/cameratraps, and we welcome new collaborating organizations.

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Temporal activity of rural free-ranging dogs: implications for the predator and prey species in the Brazilian Atlantic Forest

NeoBiota ◽

10.3897/neobiota.45.30645 ◽

2019 ◽

Vol 45 ◽

pp. 55-74 ◽

Cited By ~ 1

Author(s):

William Douglas Carvalho ◽

Luís Miguel Rosalino ◽

Maíra Sant’Ana M. Godoy ◽

Marília F. Giorgete ◽

Cristina Harumi Adania ◽

...

Keyword(s):

Atlantic Forest ◽

Native Species ◽

Prey Species ◽

Activity Patterns ◽

Site Occupancy ◽

Camera Trap ◽

Southeastern Brazil ◽

Potential Prey ◽

Large Predators ◽

Free Ranging

Domestic or free-ranging dogs (Canislupusfamiliaris) can have deleterious effects on wildlife, acting as predators or competitors to native species. These impacts can be highly important in fragmented pristine habitats or well-preserved areas located in human dominated landscapes and where biodiversity values are usually high, such as those in southeastern Brazil. Here we explored the level of overlap or mismatch in the distributions of activity patterns of rural free-ranging dogs and potential wild prey (Didelphisaurita, Cuniculuspaca; Sylvilagusbrasiliensis) and a wild predator (Leoparduspardalis) in areas of Atlantic Forest in southeastern Brazil. We further explored the possible influence of the wild predator on the dog presence pattern detected in the territory analyzed. Our camera-trap data (714 camera-trap days) showed that while rural free-ranging dogs display a cathemeral activity pattern, with activity peaks at dusk and dawn, ocelot and prey species are mainly nocturnal. Moreover, we found no evidence of an effect of ocelot presence, the distance to human houses and the presence of native forests on site occupancy by dogs. The ocelot activity patterns in this study were similar to those already reported in previous studies. On the other hand, previous studies have indicated that that free-ranging dogs are often reported to be more diurnal, and it seems that the rural free-ranging dogs in our study area may have adjusted their behaviour to be more active at dawn and dusk periods. This might be to both maintain some overlap with potential prey, e.g. Sylvilagusbrasiliensis, and also to avoid ocelots by being less active in periods when this predator is more active (which also coincides with peaks in activity for potential prey species). We hypothesize that the presence of ocelots might be influencing the temporal niche dimension of rural free-ranging dogs. As a sustainable management strategy, we propose conserving territories to promote the presence of medium to large predators in natural areas, in order to control free-ranging dogs and protect their vertebrate prey species.

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Small cat surveys: 10 years of data from Central Kalimantan, Indonesian Borneo

Journal of Threatened Taxa ◽

10.11609/jott.4466.11.4.13478-13491 ◽

2019 ◽

Vol 11 (4) ◽

pp. 13478-13491

Author(s):

Karen Anne Jeffers ◽

Adul , ◽

Susan Mary Cheyne

Keyword(s):

Habitat Suitability ◽

Activity Patterns ◽

Camera Trap ◽

Camera Traps ◽

Limited Data ◽

Central Kalimantan ◽

Temporal Partitioning ◽

Leopard Cat ◽

The Government

We present an update on the photographic detections from camera traps and the activity patterns of Borneo’s four small cats, namely, Sunda Leopard Cat Prionailurus javanensis, Flat-headed Cat P. planiceps, Marbled Cat Pardofelis marmorata, and Bay Cat Catopuma badia, at two sites in Central Kalimantan, Indonesia. Camera trap survey data of 10 years (2008–2018) from the first site in Sebangau provide details about the temporal partitioning of these small cats from each other but overlap with Sunda Clouded Leopard Neofelis diardi. The activity of Flat-headed Cat was higher after midnight and that of Leopard Cat at night with no clear preference before or after midnight. The Marbled Cat is predominantly diurnal, but the remaining three cats have flexible activity periods. While limited data are available from Rungan, the second site, we confirmed the presence of all four small cat species found on Borneo, though we have insufficient data to comment on the Bay Cat. The cat sightings, however, are intermittent and may reflect the unprotected status of this forest. Leopard Cats appear relatively unaffected by habitat disturbance based on encounter rates on camera traps. Conservationists, both NGOs and the government, must pay particular attention to specialists like Flat-headed Cats and Bay Cats when assessing habitat suitability for long-term cat conservation.

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