scholarly journals Improving the random encounter model method to estimate carnivore densities using data generated by conventional camera-trap design

Oryx ◽  
2019 ◽  
pp. 1-6 ◽  
Author(s):  
Germán Garrote ◽  
Ramón Pérez de Ayala ◽  
Antón Álvarez ◽  
José M. Martín ◽  
Manuel Ruiz ◽  
...  
Keyword(s):  
Correction Factor ◽  
Individual Recognition ◽  
Camera Traps ◽  
Individual Identification ◽  
Iberian Lynx ◽  
Surrounding Area ◽  
Lynx Pardinus ◽  
Trap Design ◽  
Capture Recapture ◽  
Using Data

Abstract The random encounter model, a method for estimating animal density using camera traps without the need for individual recognition, has been developed over the past decade. A key assumption of this model is that cameras are placed randomly in relation to animal movements, requiring that cameras are not set only at sites thought to have high animal traffic. The aim of this study was to define a correction factor that allows the random encounter model to be applied in photo-trapping surveys in which cameras are placed along tracks to maximize capture probability. Our hypothesis was that applying such a correction factor would compensate for the different rates at which lynxes use tracks and the surrounding area, and should thus improve the estimates obtained with the random encounter model. We tested this using data from a well-known Iberian lynx Lynx pardinus population. Firstly, we estimated Iberian lynx densities using a traditional camera-trapping design followed by spatially explicit capture–recapture analyses. We estimated the differential use rate for tracks vs the surrounding area using data from a lynx equipped with a GPS collar, and subsequently calculated the correction factor. As expected, the random encounter model overestimated densities by 378%. However, the application of the correction factor improved the estimate and reduced the error to 16%. Although there are limitations to the application of the correction factor, the corrected random encounter model shows potential for density estimation of species for which individual identification is not possible.

scholarly journals Estimation of the Iberian lynx (Lynx pardinus) population in the Doñana area, SW Spain, using capture–recapture analysis of camera-trapping data

2010 ◽  
Vol 57 (2) ◽  
pp. 355-362 ◽  
Author(s):  
German Garrote ◽  
Ramon Perez de Ayala ◽  
Pablo Pereira ◽  
Francisco Robles ◽  
Nicolas Guzman ◽  
...  
Keyword(s):  
Camera Trapping ◽  
Lynx Lynx ◽  
Iberian Lynx ◽  
Lynx Pardinus ◽  
Sw Spain ◽  
Capture Recapture

scholarly journals A picture is worth a thousand words: the application of camera trapping to the study of birds

2008 ◽  
Vol 18 (S1) ◽  
pp. S144-S162 ◽  
Author(s):  
Timothy G. O'Brien ◽  
Margaret F. Kinnaird
Keyword(s):  
Finite Mixture Models ◽  
Camera Trap ◽  
Camera Traps ◽  
Camera Trapping ◽  
Individual Identification ◽  
Nest Defence ◽  
Primary Forest ◽  
Sampling Effort ◽  
Observation Process ◽  
Capture Recapture

AbstractThis study reviews the use of remotely triggered still cameras, known as camera traps, in bird research and suggests new methods useful for analyzing camera trap data. Camera trapping may be most appropriate for large, ground-dwelling birds, such as cracids and pheasants. Recent applications include documentation of occurrence of rare species and new species records, nest predation studies and behavioural studies including nest defence, frugivory, seed dispersal, and activity budgets. If bird postures are analyzed, it may be possible to develop behavioural time budgets. If birds are marked or individually identifiable, abundance may be estimated through capture-recapture methods typically used for mammals. We discourage use of relative abundance indices based on trapping effort because of the difficulty of standardizing surveys over time and space. Using the Great Argus Pheasant Argus argusianus, a cryptic, terrestrial, forest bird as an example, we illustrate applications of occupancy analysis to estimate proportion of occupied habitat and finite mixture models to estimate abundance when individual identification is not possible. These analyses are useful because they incorporate detection probabilities < 1 and covariates that affect the sample site or the observation process. Results are from camera trap surveys in the 3,568 km2 Bukit Barisan Selatan National Park, Indonesia. We confirmed that Great Argus Pheasants prefer primary forest below 500 m. We also find a decline in occupancy (6–8% yr−1). Point estimates of abundance peak in 2000, followed by a sharp decline. We discuss the effects of rarity, detection probability and sampling effort on accuracy and precision of estimates.

scholarly journals Integrating spatial capture-recapture models with variable individual identifiability

2020 ◽  
Author(s):  
Joel S. Ruprecht ◽  
Charlotte E. Eriksson ◽  
Tavis D. Forrester ◽  
Darren A. Clark ◽  
Michael J. Wisdom ◽  
...  
Keyword(s):  
Puma Concolor ◽  
Individual Recognition ◽  
Population Monitoring ◽  
Lynx Rufus ◽  
Individual Identification ◽  
Telemetry Data ◽  
Density Estimates ◽  
Gps Collars ◽  
Remote Cameras ◽  
Capture Recapture

AbstractMany applications in ecology depend on unbiased and precise estimates of animal population density. Spatial capture recapture models and their variants have become the preferred tool for estimating densities of carnivores. Within the spatial capture-recapture family are variants that require individual identification of all encounters (spatial capture-recapture), individual identification of a subset of a population (spatial mark-resight), or no individual identification (spatial count). In addition, these models can incorporate telemetry data (all models) and the marking process (spatial mark-resight). However, the consistency of results among methods and the relative precision of estimates in a real-world setting are unknown. Consequently, it is unclear how much and what type of data are needed to achieve satisfactory density estimates. We tested a suite of models to estimate population densities of black bears (Ursus americanus), bobcats (Lynx rufus), cougars (Puma concolor), and coyotes (Canis latrans). For each species we genotyped fecal DNA collected with detection dogs. A subset of individuals from each species were affixed with GPS collars bearing unique markings to be resighted by remote cameras set on a 1 km grid. We fit 10 models for each species ranging from those requiring no animals to be individually recognizable to others that necessitate full individual recognition. We then assessed the contribution of incorporating telemetry data to each model and the marking process to the mark-resight model. Finally, we developed an integrated hybrid model that combines camera, physical capture, genetic, and GPS data into a single hierarchical model. Importantly, we find that spatial count models that do not individually identify animals fail in all cases whether or not telemetry data are included. Results improved as models contained more information on individual identity. Models where a subset of individuals were identifiable yielded qualitatively similar results, but can produce quantitatively divergent estimates, suggesting that long-term population monitoring should use a consistent method across years. Incorporation of telemetry data and the marking process can produce more accurate and precise density estimates. Our results can be used to guide future study designs to efficiently estimate carnivore densities for better understanding of population dynamics, predator-prey relationships, and community assemblages.

scholarly journals Where to spot: individual identification of leopard cats (Prionailurus bengalensis euptilurus) in South Korea

2019 ◽  
Vol 43 (1) ◽  
Author(s):  
Heebok Park ◽  
Anya Lim ◽  
Tae-Young Choi ◽  
Seung-Yoon Baek ◽  
Eui-Geun Song ◽  
...  
Keyword(s):  
South Korea ◽  
Wildlife Conservation ◽  
Camera Traps ◽  
Individual Identification ◽  
Parameter Estimates ◽  
Population Parameter ◽  
Study Results ◽  
Capture Recapture ◽  
Leopard Cat ◽  
Prionailurus Bengalensis

AbstractKnowledge of abundance, or population size, is fundamental in wildlife conservation and management. Camera-trapping, in combination with capture-recapture methods, has been extensively applied to estimate abundance and density of individually identifiable animals due to the advantages of being non-invasive, effective to survey wide-ranging, elusive, or nocturnal species, operating in inhospitable environment, and taking low labor. We assessed the possibility of using coat patterns from images to identify an individual leopard cat (Prionailurus bengalensis), a Class II endangered species in South Korea. We analyzed leopard cat images taken from Digital Single-Lense Relfex camera (high resolution, 18Mpxl) and camera traps (low resolution, 3.1Mpxl) using HotSpotter, an image matching algorithm. HotSpotter accurately top-ranked an image of the same individual leopard cat with the reference leopard cat image 100% by matching facial and ventral parts. This confirms that facial and ventral fur patterns of the Amur leopard cat are good matching points to be used reliably to identify an individual. We anticipate that the study results will be useful to researchers interested in studying behavior or population parameter estimates of Amur leopard cats based on capture-recapture models.

scholarly journals Spatially Explicit Capture-Recapture Through Camera Trapping: A Review of Benchmark Analyses for Wildlife Density Estimation

2020 ◽  
Vol 8 ◽  
Author(s):  
Austin M. Green ◽  
Mark W. Chynoweth ◽  
Çağan Hakkı Şekercioğlu
Keyword(s):  
Density Estimation ◽  
Study Design ◽  
New Technologies ◽  
Model Development ◽  
Population Monitoring ◽  
Camera Traps ◽  
Camera Trapping ◽  
Individual Identification ◽  
Spatially Explicit ◽  
Capture Recapture

Camera traps have become an important research tool for both conservation biologists and wildlife managers. Recent advances in spatially explicit capture-recapture (SECR) methods have increasingly put camera traps at the forefront of population monitoring programs. These methods allow for benchmark analysis of species density without the need for invasive fieldwork techniques. We conducted a review of SECR studies using camera traps to summarize the current focus of these investigations, as well as provide recommendations for future studies and identify areas in need of future investigation. Our analysis shows a strong bias in species preference, with a large proportion of studies focusing on large felids, many of which provide the only baseline estimates of population density for these species. Furthermore, we found that a majority of studies produced density estimates that may not be precise enough for long-term population monitoring. We recommend simulation and power analysis be conducted before initiating any particular study design and provide examples using readily available software. Furthermore, we show that precision can be increased by including a larger study area that will subsequently increase the number of individuals photo-captured. As many current studies lack the resources or manpower to accomplish such an increase in effort, we recommend that researchers incorporate new technologies such as machine-learning, web-based data entry, and online deployment management into their study design. We also cautiously recommend the potential of citizen science to help address these study design concerns. In addition, modifications in SECR model development to include species that have only a subset of individuals available for individual identification (often called mark-resight models), can extend the process of explicit density estimation through camera trapping to species not individually identifiable.

Current Status Of the Iberian Lynx (Lynx pardinus) in Eastern Sierra Morena, Southern Spain

2010 ◽  
Vol 6 (3) ◽  
Author(s):  
José María Gil-Sánchez ◽  
Miguel Angel Simón ◽  
Rafael Cadenas ◽  
José Bueno ◽  
Manuel Moral ◽  
...  
Keyword(s):  
Southern Spain ◽  
Current Status ◽  
Lynx Lynx ◽  
Iberian Lynx ◽  
Lynx Pardinus ◽  
Sierra Morena

scholarly journals Leopard Density Estimation within an Enclosed Reserve, Namibia Using Spatially Explicit Capture-Recapture Models

Animals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 724
Author(s):  
Noack ◽  
Heyns ◽  
Rodenwoldt ◽  
Edwards
Keyword(s):  
Management Strategies ◽  
Camera Traps ◽  
Spatially Explicit ◽  
Conservation Areas ◽  
Term Survival ◽  
New Class ◽  
Capture Recapture ◽  
Wildlife Populations ◽  
Effective Conservation

The establishment of enclosed conservation areas are claimed to be the driving force for the long-term survival of wildlife populations. Whilst fencing provides an important tool in conservation, it simultaneously represents a controversial matter as it stops natural migration processes, which could ultimately lead to inbreeding, a decline in genetic diversity and local extinction if not managed correctly. Thus, wildlife residing in enclosed reserves requires effective conservation and management strategies, which are strongly reliant on robust population estimates. Here, we used camera traps combined with the relatively new class of spatially explicit capture-recaptured models (SECR) to produce the first reliable leopard population estimate for an enclosed reserve in Namibia. Leopard density was estimated at 14.51 leopards/100 km2, the highest recorded density in Namibia to date. A combination of high prey abundance, the absence of human persecution and a lack of top-down control are believed to be the main drivers of the recorded high leopard population. Our results add to the growing body of literature which suggests enclosed reserves have the potential to harbour high densities and highlight the importance of such reserves for the survival of threatened species in the future.

scholarly journals Detection ofFeline Leukemia Virusin the Endangered Iberian Lynx (Lynx Pardinus)

2008 ◽  
Vol 20 (3) ◽  
pp. 381-385 ◽  
Author(s):  
Inés Luaces ◽  
Ana Doménech ◽  
Marino García-Montijano ◽  
Victorio M. Collado ◽  
Celia Sónchez ◽  
...  
Keyword(s):  
Lynx Lynx ◽  
Iberian Lynx ◽  
Lynx Pardinus

scholarly journals The wildcat Felis silvestris in northern Turkey: assessment of status using camera trapping

Oryx ◽  
2011 ◽  
Vol 45 (1) ◽  
pp. 112-118 ◽  
Author(s):  
Özgün Emre Can ◽  
İrfan Kandemi̇r ◽  
İnci̇ Togan
Keyword(s):  
Population Size ◽  
Camera Traps ◽  
Sampling Effort ◽  
Felis Silvestris ◽  
Forest Patch ◽  
Western Turkey ◽  
Lack Of Information ◽  
The Status ◽  
Capture Recapture ◽  
Estimate Population Size

AbstractThe wildcat Felis silvestris is a protected species in Turkey but the lack of information on its status is an obstacle to conservation initiatives. To assess the status of the species we interviewed local forestry and wildlife personnel and conducted field surveys in selected sites in northern, eastern and western Turkey during 2000–2007. In January–May 2006 we surveyed for the wildcat using 16 passive infrared-trigged camera traps in Yaylacı k Research Forest, a 50-km2 forest patch in Yenice Forest in northern Turkey. A total sampling effort of 1,200 camera trap days over 40 km2 yielded photo-captures of eight individual wildcats over five sampling occasions. Using the software MARK to estimate population size the closed capture–recapture model M0, which assumes a constant capture probability among all occasions and individuals, best fitted the capture history data. The wildcat population size in Yaylacı k Research Forest was estimated to be 11 (confidence interval 9–23). Yenice Forest is probably one of the most important areas for the long-term conservation of the wildcat as it is the largest intact forest habitat in Turkey with little human presence, and without human settlements, and with a high diversity of prey species. However, it has been a major logging area and is not protected. The future of Yenice Forest and its wildcat population could be secured by granting this region a protection status and enforcing environmental legislation.

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