scholarly journals Density estimation of tiger and leopard using spatially explicit capture–recapture framework

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10634
Author(s):  
Tahir Ali Rather ◽  
Sharad Kumar ◽  
Jamal Ahmad Khan
Keyword(s):  
Protected Areas ◽  
Management Strategies ◽  
Natural Vegetation ◽  
Camera Traps ◽  
Spatially Explicit ◽  
Panthera Tigris ◽  
Large Carnivores ◽  
Road Density ◽  
Buffer Zones ◽  
Capture Recapture

The conservation of large carnivores often requires precise and accurate estimates of their populations. Being cryptic and occurring at low population densities, obtaining an unbiased population estimate is difficult in large carnivores. To overcome the uncertainties in the conventional capture–recapture (CR) methods used to estimate large carnivore densities, more robust methods such as spatially explicit capture-recapture (SECR) framework are now widely used. We modeled the CR data of tiger (Panthera tigris tigris) and leopard (Panthera pardus fusca) in the SECR framework with biotic and abiotic covariates likely believed to influence their densities. An effort of 2,211 trap nights resulted in the capture of 33 and 38 individual tigers and leopards. A total of 95 and 74 detections of tigers and leopards were achieved using 35 pairs of camera traps. Tiger and leopard density were estimated at 4.71 ± 1.20 (3.05–5.11) and 3.03 ± 0.78 (1.85–4.99) per 100 km2. Our results show that leopard density increased with high road density, high terrain ruggedness and habitats with high percentage of cropland and natural vegetation. The tiger density was positively influenced by the mosaic of cropland and natural vegetation. This study provides the first robust density estimates of tiger and leopard within the study area. Our results support the notion that large carnivores can attain moderate densities within human-dominated regions around protected areas relying on domestic livestock. Broader management strategies aimed at maintaining wild prey in the human-dominated areas around protected areas are necessary for large and endangered carnivores’ sustenance in the buffer zones around protected areas.

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 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 Threatened predator on the equator: multi-point abundance estimates of the tiger Panthera tigris in central Sumatra

Oryx ◽  
2013 ◽  
Vol 47 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Sunarto ◽  
Marcella J. Kelly ◽  
Sybille Klenzendorf ◽  
Michael R. Vaughan ◽  
Zulfahmi ◽  
...  
Keyword(s):  
Camera Traps ◽  
Spatial And Temporal Variation ◽  
Spatially Explicit ◽  
Panthera Tigris ◽  
Forest Types ◽  
Lowland Forest ◽  
Abundance Estimates ◽  
Capture Recapture ◽  
Central Sumatra ◽  
Insight Into

AbstractInformation on spatial and temporal variation in abundance is crucial for effective management of wildlife. Yet abundance estimates for the Critically Endangered Sumatran tiger Panthera tigris sumatrae are lacking from Riau, the province historically believed to hold the largest percentage of this subspecies. Recently, this area has had one of the highest global rates of deforestation. Using camera traps we investigated tiger abundance across peatland, flat lowland, and hilly lowland forest types in the province, and over time, in the newly established Tesso Nilo National Park, central Sumatra. We estimated densities using spatially explicit capture–recapture, calculated with DENSITY, and traditional capture–recapture models, calculated with CAPTURE. With spatially explicit capture–recapture the lowest tiger density (0.34 ± SE 0.24 per 100 km2) was estimated in the hilly lowland forest of Rimbang Baling and the highest (0.87 ± SE 0.33 per 100 km2) in the flat lowland forest of the Park. Repeated surveys in the Park documented densities of 0.63 ± SE 0.28 in 2005 to 0.87 ± SE 0.33 per 100 km2 in 2008. Compared to traditional capture–recapture the spatially explicit capture–recapture approach resulted in estimates 50% lower. Estimates of tiger density from this study were lower than most previous estimates in other parts of Sumatra. High levels of human activity in the area appear to limit tigers. The results of this study, which covered areas and habitat types not previously surveyed, are important for overall population estimates across the island, provide insight into the response of carnivores to habitat loss, and are relevant to the interventions needed to save the tiger.

scholarly journals Do conservation strategies that increase tiger populations have consequences for other wild carnivores like leopards?

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ujjwal Kumar ◽  
Neha Awasthi ◽  
Qamar Qureshi ◽  
Yadvendradev Jhala
Keyword(s):  
Species Conservation ◽  
Camera Trap ◽  
Conservation Strategies ◽  
Spatially Explicit ◽  
Large Carnivores ◽  
Catchment Scale ◽  
Large Carnivore ◽  
Positive Growth ◽  
Capture Recapture ◽  
Very High

Abstract Most large carnivore populations are declining across their global range except in some well managed protected areas (PA’s). Investments for conserving charismatic apex carnivores are often justified due to their umbrella effect on biodiversity. We evaluate population trends of two large sympatric carnivores, the tiger and leopard through spatially-explicit-capture-recapture models from camera trap data in Kanha PA, India, from 2011 to 2016. Our results show that the overall density (100 km−2) of tigers ranged between 4.82 ± 0.33 to 5.21 ± 0.55SE and of leopards between 6.63 ± 0.71 to 8.64 ± 0.75SE, with no detectable trends at the PA scale. When evaluated at the catchment scale, Banjar catchment that had higher prey density and higher conservation investments, recorded significant growth of both carnivores. While Halon catchment, that had lower prey and conservation investments, populations of both carnivores remained stable. Sex ratio of both carnivores was female biased. As is typical with large carnivores, movement parameter sigma (an index for range size), was larger for males than for females. However, sigma was surprisingly similar for the same genders in both carnivores. At home-range scale, leopards achieved high densities and positive growth rates in areas that had low, medium or declining tiger density. Our results suggest that umbrella-species conservation value of tigers is likely to be compromised at very high densities and therefore should not be artificially inflated through targeted management.

scholarly journals Ecological preferences of large carnivores in remote, high-altitude protected areas: insights from Buxa Tiger Reserve, India

Oryx ◽  
2017 ◽  
Vol 52 (1) ◽  
pp. 66-77 ◽  
Author(s):  
Mriganka Shekhar Sarkar ◽  
Harika Segu ◽  
J. V. Bhaskar ◽  
Rajendra Jakher ◽  
Swati Mohapatra ◽  
...  
Keyword(s):  
High Altitude ◽  
Protected Areas ◽  
Protected Area ◽  
Faecal Sample ◽  
Prey Species ◽  
Panthera Tigris ◽  
Large Carnivores ◽  
Tiger Reserve ◽  
Faecal Samples ◽  
Geographical Regions

AbstractDifficult terrain and inclement weather limit our knowledge of large predators, such as the tiger Panthera tigris, in the Himalayas. A lack of empirical data on large carnivores can lead to mismanagement of protected areas and population declines. We used non-invasive genetic and remote sensing data to inform the management of such high-altitude protected areas. We used the tiger as a focal species to investigate prey preference and habitat suitability in India's Buxa Tiger Reserve, which encompasses several eco-geographical regions in the Himalayan and subtropical zones. During 2010–2013, 909 faecal samples were collected, of which 372 were confirmed, using genetic analysis, to be of tiger origin. Fourteen prey species/groups were identified in 240 tiger faecal samples, largely dominated by goats Capra spp. (26.59%), rhesus macaques Macaca mulatta (22.22%) and cattle Bos spp. (20.63%). Considering only the wild prey species for which survey data are available, however, and frequency of occurrence of prey in faecal samples, hog deer Axis porcinus, sambar deer Rusa unicolor and spotted deer Axis axis were the most preferred prey species. Using faecal sample locations to examine the relationship between tiger presence and environmental features indicated that the niche for tigers is narrower than the available protected area: c. 62% of core protected area is suitable, of which only 17% is highly suitable for tigers. Tigers prefer dense vegetation, open forests, riverine vegetation and areas close to water sources. Faecal sample-based studies have the potential to generate data that can help us understand the ecology of elusive carnivore species inhabiting high-altitude landscapes.

scholarly journals An empirical demonstration of the effect of study design on density estimations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad Ali Nawaz ◽  
Barkat Ullah Khan ◽  
Amer Mahmood ◽  
Muhammad Younas ◽  
Jaffar ud Din ◽  
...  
Keyword(s):  
Rare Species ◽  
Sampling Design ◽  
Space Use ◽  
Camera Traps ◽  
Large Carnivores ◽  
Large Mammals ◽  
Spatial Coverage ◽  
Capture Recapture ◽  
Compact Design ◽  
Empirical Demonstration

AbstractThe simultaneous development of technology (e.g. camera traps) and statistical methods, particularly spatially capture–recapture (SCR), has improved monitoring of large mammals in recent years. SCR estimates are known to be sensitive to sampling design, yet existing recommendations about trap spacing and coverage are often not achieved, particularly for sampling wide-ranging and rare species in landscapes that allow for limited accessibility. Consequently, most camera trap studies on large wide-ranging carnivores relies on convenience or judgmental sampling, and often yields compromised results. This study attempts to highlight the importance of carefully considered sampling design for large carnivores that, because of low densities and elusive behavior, are challenging to monitor. As a motivating example, we use two years of snow leopard camera trapping data from the same areas in the high mountains of Pakistan but with vastly different camera configurations, to demonstrate that estimates of density and space use are indeed sensitive to the trapping array. A compact design, one in which cameras were placed much closer together than generally recommended and therefore have lower spatial coverage, resulted in fewer individuals observed, but more recaptures, and estimates of density and space use were inconsistent with expectations for the region. In contrast, a diffuse design, one with larger spacing and spatial coverage and more consistent with general recommendations, detected more individuals, had fewer recaptures, but generated estimates of density and space use that were in line with expectations. Researchers often opt for compact camera configurations while monitoring wide-ranging and rare species, in an attempt to maximize the encounter probabilities. We empirically demonstrate the potential for biases when sampling a small area approximately the size of a single home range—this arises from exposing fewer individuals than deemed sufficient for estimation. The smaller trapping array may also underestimate density by significantly inflating $$\sigma$$ σ . On the other hand, larger trapping array with fewer detectors and poor design induces uncertainties in the estimates. We conclude that existing design recommendations have limited utility on practical grounds for devising feasible sampling designs for large ranging species, and more research on SCR designs is required that allows for integrating biological and habitat traits of large carnivores in sampling framework. We also suggest that caution should be exercised when there is a reliance on convenience sampling.

scholarly journals Assessment of fine-scale resource selection and spatially explicit habitat suitability modelling for a re-introduced tiger (Panthera tigris) population in central India

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3920 ◽  
Author(s):  
Mriganka Shekhar Sarkar ◽  
Ramesh Krishnamurthy ◽  
Jeyaraj A. Johnson ◽  
Subharanjan Sen ◽  
Goutam Kumar Saha
Keyword(s):  
Habitat Selection ◽  
Habitat Suitability ◽  
Resource Selection ◽  
Central India ◽  
Spatially Explicit ◽  
Panthera Tigris ◽  
Large Carnivores ◽  
Fine Scale ◽  
Selection Strategies ◽  
Tiger Population

Background Large carnivores influence ecosystem functions at various scales. Thus, their local extinction is not only a species-specific conservation concern, but also reflects on the overall habitat quality and ecosystem value. Species-habitat relationships at fine scale reflect the individuals’ ability to procure resources and negotiate intraspecific competition. Such fine scale habitat choices are more pronounced in large carnivores such as tiger (Panthera tigris), which exhibits competitive exclusion in habitat and mate selection strategies. Although landscape level policies and conservation strategies are increasingly promoted for tiger conservation, specific management interventions require knowledge of the habitat correlates at fine scale. Methods We studied nine radio-collared individuals of a successfully reintroduced tiger population in Panna Tiger Reserve, central India, focussing on the species-habitat relationship at fine scales. With 16 eco-geographical variables, we performed Manly’s selection ratio and K-select analyses to define population-level and individual-level variation in resource selection, respectively. We analysed the data obtained during the exploratory period of six tigers and during the settled period of eight tigers separately, and compared the consequent results. We further used the settled period characteristics to model and map habitat suitability based on the Mahalanobis D2 method and the Boyce index. Results There was a clear difference in habitat selection by tigers between the exploratory and the settled period. During the exploratory period, tigers selected dense canopy and bamboo forests, but also spent time near villages and relocated village sites. However, settled tigers predominantly selected bamboo forests in complex terrain, riverine forests and teak-mixed forest, and totally avoided human settlements and agriculture areas. There were individual variations in habitat selection between exploratory and settled periods. Based on threshold limits of habitat selection by the Boyce Index, we established that 83% of core and 47% of buffer areas are now suitable habitats for tiger in this reserve. Discussion Tiger management often focuses on large-scale measures, but this study for the first time highlights the behaviour and fine-scale individual-specific habitat selection strategies. Such knowledge is vital for management of critical tiger habitats and specifically for the success of reintroduction programs. Our spatially explicit habitat suitability map provides a baseline for conservation planning and optimizing carrying capacity of the tiger population in this reserve.

scholarly journals Rapid recovery of tigers Panthera tigris in Parsa Wildlife Reserve, Nepal

Oryx ◽  
2017 ◽  
Vol 52 (1) ◽  
pp. 16-24 ◽  
Author(s):  
Babu Ram Lamichhane ◽  
Chiranjibi Prasad Pokheral ◽  
Shashank Poudel ◽  
Dipendra Adhikari ◽  
Sailendra Raj Giri ◽  
...  
Keyword(s):  
Camera Traps ◽  
Suitable Habitat ◽  
Source Population ◽  
Anthropogenic Pressure ◽  
Panthera Tigris ◽  
Population Turnover ◽  
Capture Recapture ◽  
Chitwan National Park ◽  
Ecological Unit ◽  
Wildlife Reserve

AbstractInformation on density and abundance of globally threatened species such as tigers Panthera tigris is essential for effective conservation as well as to evaluate the success of conservation programmes. We monitored tigers in Parsa Widlife Reserve, Nepal, using camera traps, in 2013, 2014 and 2016. Once believed to be a sink for tigers from adjacent Chitwan National Park, Parsa now provides a new hope for tigers. Spatially explicit capture–recapture analysis over 3 survey years revealed an increase in tiger density from 0.78 to 1.38 individuals per 100 km2 from 2013 to 2016. The tiger abundance was estimated to be seven (6–13), 11 (10–16) and 17 (17–20) in 2013, 2014 and 2016, respectively. Resettlement of communities from the core area, reduced anthropogenic pressure, and improved security have made Parsa Wildlife Reserve a suitable habitat for tigers. Tiger abundance increased considerably within a 5 km radius of the evacuated village sites, from two in 2013 to eight in 2014 and 10 in 2016. Population turnover has remained moderate (< 30% per year), with persistence of individuals in multiple years. Dispersing tigers from Chitwan's source population accounted for a large portion (c. 40%) of the tigers detected in Parsa. Conservation efforts along with annual monitoring should be continued in Parsa to sustain the increase and monitor the persistence of tigers. The Chitwan–Parsa complex should be managed as a single ecological unit for conserving the Endangered tiger and other wide-ranging species.

scholarly journals Buffer zone use by mammals in a Cerrado protected area

2016 ◽  
Vol 16 (2) ◽  
Author(s):  
Roberta Montanheiro Paolino ◽  
Natalia Fraguas Versiani ◽  
Nielson Pasqualotto ◽  
Thiago Ferreira Rodrigues ◽  
Victor Gasperotto Krepschi ◽  
...  
Keyword(s):  
Protected Areas ◽  
Puma Concolor ◽  
Buffer Zone ◽  
Camera Traps ◽  
Imperfect Detection ◽  
Mammal Species ◽  
Buffer Zones ◽  
Terrestrial Mammals ◽  
External Threats ◽  
The Impact

Habitat loss and degradation is threatening mammals worldwide. Therefore, Protected Areas (PA) are of utmost importance to preserve biodiversity. Their effectiveness, however, depends on some management strategies such as buffer zones, which prevent/mitigate the impact of external threats and might increase the amount of available habitat for wildlife existing within reserves. Nevertheless, how intensively terrestrial mammals use buffer zones remains little studied, particularly in the Neotropical region. Aiming to analyse the use of a buffer zone (5 km wide) by medium and large-sized mammals, we modelled the occupancy probabilities of five species of conservation concern including local (interior and buffer zone) as a site covariate, simultaneously controlling for imperfect detection. Data collection was made with camera traps from April to September 2013 in a 9000 ha Cerrado PA (“interior”) and in its surrounding area (39721.41 ha; “buffer zone”). This PA (Jataí Ecological Station) is immersed in a landscape where sugarcane plantations predominate in the northeastern of the state of São Paulo. We also conducted an inventory to compare the number and composition of species between interior and buffer zone. A total of 31 mammal species (26 natives) was recorded via camera traps and active search for sightings, vocalizations, tracks and signs. Occupancy estimates for Myrmecophaga tridactyla, Leopardus pardalis and Pecari tajacu were numerically higher in interior. On the other hand, Chrysocyon brachyurus had the highest occupancy in buffer zone, while the largest predator, Puma concolor, used both areas similarly. However, as the confidence intervals (95%) overlapped, the differences in occupancy probabilities between interior and buffer were weak for all these species. Additionally, regarding only the species recorded by cameras, the observed and estimated richness were similar between interior and buffer zone of the PA. Our data demonstrated that the buffer zone is indeed used by medium and large-sized mammals, including conservation-dependent ones. The lack of enforcement of current legislation regarding buffer zones is therefore a real threat for mammals, even when protection is guaranteed in the interior of protected areas.

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