scholarly journals Spatial capture–recapture with partial identity: An application to camera traps

2018 ◽  
Vol 12 (1) ◽  
pp. 67-95 ◽  
Author(s):  
Ben C. Augustine ◽  
J. Andrew Royle ◽  
Marcella J. Kelly ◽  
Christopher B. Satter ◽  
Robert S. Alonso ◽  
...  
Keyword(s):  
Camera Traps ◽  
Partial Identity ◽  
Capture Recapture

scholarly journals A Spatially Explicit Capture–Recapture Model for Partially Identified Individuals When Trap Detection Rate Is Less than One

2019 ◽  
Vol 71 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Soumen Dey ◽  
Mohan Delampady ◽  
K. Ullas Karanth ◽  
Arjun M. Gopalaswamy
Keyword(s):  
Detection Probability ◽  
Credible Interval ◽  
Camera Traps ◽  
Spatially Explicit ◽  
Panthera Tigris ◽  
Partial Identity ◽  
Proposed Model ◽  
Estimation Problems ◽  
Capture Recapture ◽  
Future Work

Spatially explicit capture–recapture (SECR) models have gained enormous popularity to solve abundance estimation problems in ecology. In this study, we develop a novel Bayesian SECR model that disentangles two processes: one is the process of animal arrival within a detection region, and the other is the process of recording this arrival by a given set of detectors. We integrate this complexity into an advanced version of a recent SECR model involving partially identified individuals (Royle JA. Spatial capture-recapture with partial identity. arXiv preprint arXiv:1503.06873, 2015). We assess the performance of our model over a range of realistic simulation scenarios and demonstrate that estimates of population size N improve when we utilize the proposed model relative to the model that does not explicitly estimate trap detection probability (Royle JA. Spatial capture-recapture with partial identity. arXiv preprint arXiv:1503.06873, 2015). We confront and investigate the proposed model with a spatial capture–recapture dataset from a camera trapping survey of tigers (Panthera tigris) in Nagarahole study area of southern India. Detection probability is estimated at 0.489 (with 95% credible interval (CI) [0.430, 0.543]) which implies that the camera traps are performing imperfectly and thus justifying the use of our model in real world applications. We discuss possible extensions, future work and relevance of our model to other statistical applications beyond ecology. AMS classification codes: 62F15, 92D40

scholarly journals Spatial Capture-Recapture with Partial Identity: An Application to Camera Traps

2016 ◽  
Author(s):  
Ben C. Augustine ◽  
J. Andrew Royle ◽  
Marcella J. Kelly ◽  
Christopher B. Satter ◽  
Robert S. Alonso ◽  
...  
Keyword(s):  
Spatial Location ◽  
Camera Traps ◽  
Camera Trapping ◽  
Single Camera ◽  
Data Types ◽  
Data Set ◽  
Partial Identity ◽  
Capture Recapture ◽  
Identity Model ◽  
Camera Design

Camera trapping surveys frequently capture individuals whose identity is only known from a single flank. The most widely used methods for incorporating these partial identity individuals into density analyses discard some of the partial identity capture histories, reducing precision, and while not previously recognized, introducing bias. Here, we present the spatial partial identity model (SPIM), which uses the spatial location where partial identity samples are captured to probabilistically resolve their complete identities, allowing all partial identity samples to be used in the analysis. We show that the SPIM out-performs other analytical alternatives. We then apply the SPIM to an ocelot data set collected on a trapping array with double-camera stations and a bobcat data set collected on a trapping array with single-camera stations. The SPIM improves inference in both cases and in the ocelot example, individual sex determined from photographs is used to further resolve partial identities, one of which is resolved to near certainty. The SPIM opens the door for the investigation of trapping designs that deviate from the standard 2 camera design, the combination of other data types between which identities cannot be deterministically linked, and can be extended to the problem of partial genotypes.

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 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.

scholarly journals Density Estimates of Unmarked Large Mammals at Camera Traps Vary among Models, Species, and Years, Signalling Importance of Model Assumptions

2021 ◽  
Author(s):  
Jason Fisher ◽  
Joanna Burgar ◽  
Melanie Dickie ◽  
Cole Burton ◽  
Rob Serrouya
Keyword(s):  
Density Estimation ◽  
Black Bear ◽  
Camera Traps ◽  
Mammal Species ◽  
Density Estimates ◽  
Movement Rates ◽  
Social Species ◽  
Marked Variability ◽  
Capture Recapture ◽  
Best Fitting

Density estimation is a key goal in ecology but accurate estimates remain elusive, especially for unmarked animals. Data from camera-trap networks combined with new density estimation models can bridge this gap but recent research has shown marked variability in accuracy, precision, and concordance among estimators. We extend this work by comparing estimates from two different classes of models: unmarked spatial capture-recapture (spatial count, SC) models, and Time In Front of Camera (TIFC) models, a class of random encounter model. We estimated density for four large mammal species with different movement rates, behaviours, and sociality, as these traits directly relate to model assumptions. TIFC density estimates were typically higher than SC model estimates for all species. Black bear TIFC estimates were ~ 10-fold greater than SC estimates. Caribou TIFC estimates were 2-10 fold greater than SC estimates. White-tailed deer TIFC estimates were up to 100-fold greater than SC estimates. Differences of 2-5 fold were common for other species in other years. SC estimates were annually stable except for one social species; TIFC estimates were highly annually variable in some cases and consistent in others. Tests against densities obtained from DNA surveys and aerial surveys also showed variable concordance and divergence. For gregarious animals TIFC may outperform SC due to the latter model’s assumption of independent activity centres. For curious animals likely to investigate camera traps, SC may outperform TIFC, which assumes animal behavior is unaffected by cameras. Unmarked models offer great possibilities, but a pragmatic approach employs multiple estimators where possible, considers the ecological plausibility of assumptions, and uses an informed multi-inference approach to seek estimates from models with assumptions best fitting a species’ biology.

scholarly journals The use of camera traps for estimating jaguar Panthera onca abundance and density using capture/recapture analysis

Oryx ◽  
2004 ◽  
Vol 38 (2) ◽  
pp. 148-154 ◽  
Author(s):  
Scott C. Silver ◽  
Linde E. T. Ostro ◽  
Laura K. Marsh ◽  
Leonardo Maffei ◽  
Andrew J. Noss ◽  
...  
Keyword(s):  
Economic Value ◽  
Sampling Technique ◽  
Camera Traps ◽  
Dry Forest ◽  
Panthera Onca ◽  
Survey Technique ◽  
Capture Recapture ◽  
Amazonian Rainforest ◽  
Study Sites

Across their range jaguars Panthera onca are important conservation icons for several reasons: their important role in ecosystems as top carnivores, their cultural and economic value, and their potential conflicts with livestock. However, jaguars have historically been difficult to monitor. This paper outlines the first application of a systematic camera trapping methodology for abundance estimation of jaguars. The methodology was initially developed to estimate tiger abundance in India. We used a grid of camera traps deployed for 2 months, identified individual animals from their pelage patterns, and estimated population abundance using capture-recapture statistical models. We applied this methodology in a total of five study sites in the Mayan rainforest of Belize, the Chaco dry forest of Bolivia, and the Amazonian rainforest of Bolivia. Densities were 2.4–8.8 adult individuals per 100 km2, based on 7–11 observed animals, 16–37 combined ‘captures’ and ‘recaptures’, 486–2,280 trap nights, and sample areas of 107–458 km2. The sampling technique will be used to continue long-term monitoring of jaguar populations at the same sites, to compare with further sites, and to develop population models. This method is currently the only systematic population survey technique for jaguars, and has the potential to be applied to other species with individually recognizable markings.

scholarly journals Accurate population estimation of Caprinae using camera traps and distance sampling

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Grant M. Harris ◽  
Matthew J. Butler ◽  
David R. Stewart ◽  
Eric M. Rominger ◽  
Caitlin Q. Ruhl
Keyword(s):  
Chihuahuan Desert ◽  
Distance Sampling ◽  
Sampling Technique ◽  
Ovis Canadensis ◽  
Camera Traps ◽  
Distribution Data ◽  
Confidence Bounds ◽  
Desert Bighorn Sheep ◽  
Capture Recapture ◽  
Data Deficient

Abstract With most of the world’s Caprinae taxa threatened with extinction, the IUCN appeals to the development of simple and affordable sampling methods that will produce credible abundance and distribution data for helping conserve these species inhabiting remote areas. Traditional sampling approaches, like aerial sampling or mark-capture-recapture, can generate bias by failing to meet sampling assumptions, or by incurring too much cost and logistical burden for most projects to address them. Therefore, we met the IUCN’s challenge by testing a sampling technique that leverages imagery from camera traps with conventional distance sampling, validating its operability in mountainous topography by comparing results to known abundances. Our project occurred within a captive facility housing a wild population of desert bighorn sheep (Ovis canadensis) in the Chihuahuan desert of New Mexico, which is censused yearly. True abundance was always within our 90% confidence bounds, and the mean abundance estimates were within 4.9 individuals (average) of the census values. By demonstrating the veracity of this straightforward and inexpensive sampling method, we provide confidence in its operability, urging its use to fill conservation voids for Caprinae and other data-deficient species inhabiting rugged or heavily vegetated terrain.

scholarly journals An assessment of carnivore relative abundance and density in the eastern rainforests of Madagascar using remotely-triggered camera traps

Oryx ◽  
2010 ◽  
Vol 44 (2) ◽  
pp. 219-222 ◽  
Author(s):  
Brian Gerber ◽  
Sarah M. Karpanty ◽  
Charles Crawford ◽  
Mary Kotschwar ◽  
Johnny Randrianantenaina
Keyword(s):  
Relative Abundance ◽  
National Park ◽  
Camera Trap ◽  
Camera Traps ◽  
Domestic Dog ◽  
Likelihood Method ◽  
Ranomafana National Park ◽  
Carnivore Species ◽  
Cryptoprocta Ferox ◽  
Capture Recapture

AbstractDespite major efforts to understand and conserve Madagascar’s unique biodiversity, relatively little is known about the island’s carnivore populations. We therefore deployed 43 camera-trap stations in Ranomafana National Park, Madagascar during June–August 2007 to evaluate the efficacy of this method for studying Malagasy carnivores and to estimate the relative abundance and density of carnivores in the eastern rainforest. A total of 755 camera-trap nights provided 1,605 photographs of four endemic carnivore species (fossa Cryptoprocta ferox, Malagasy civet Fossa fossana, ring-tailed mongoose Galidia elegans and broad-striped mongoose Galidictus fasciata), the exotic Indian civet Viverricula indica and the domestic dog Canis familiaris. We identified 38 individual F. fossana and 10 individual C. ferox. We estimated density using both capture-recapture analyses, with a buffer of full mean-maximum-distance-moved, and a spatially-explicit maximum-likelihood method (F. fossana: 3.03 and 2.23 km-2, respectively; C. ferox: 0.15 and 0.17 km-2, respectively). Our estimated densities of C. ferox in rainforest are lower than published estimates for conspecifics in the western dry forests. Within Ranomafana National Park species richness of native carnivores did not vary among trail systems located in secondary, selectively-logged and undisturbed forest. These results provide the first assessment of carnivore population parameters using camera-traps in the eastern rainforests of Madagascar.

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