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 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 Evaluating deepwater fisheries management strategies using a mixed-fisheries and spatially explicit modelling framework

2013 ◽  
Vol 70 (4) ◽  
pp. 768-781 ◽  
Author(s):  
Paul Marchal ◽  
Youen Vermard
Keyword(s):  
Fisheries Management ◽  
Management Strategies ◽  
Spatially Explicit ◽  
Catch Per Unit Effort ◽  
Modelling Framework ◽  
Control Rules ◽  
Bioeconomic Modelling ◽  
Stock Assessments ◽  
Fleet Dynamics

Abstract Marchal, P., and Vermard, Y. 2013. Evaluating deepwater fisheries management strategies using a mixed-fisheries and spatially explicit modelling framework. – ICES Journal of Marine Science, 70: 768–781. We have used in this study a spatially explicit bioeconomic modelling framework to evaluate management strategies, building in both data-rich and data-limited harvest control rules (HCRs), for a mix of deepwater fleets and species, on which information is variable. The main focus was on blue ling (Molva dypterygia). For that species, both data-rich and data-limited HCRs were tested, while catch per unit effort (CPUE) was used either to tune stock assessments, or to directly trigger management action. There were only limited differences between the performances of both HCRs when blue ling biomass was initialized at the current level, but blue ling recovered more quickly with the data-rich HCR when its initial biomass was severely depleted. Both types of HCR lead, on average, to a long-term recovery of both blue ling and saithe (Pollachius virens) stocks, and some increase in overall profit. However, that improvement is not sufficient to guarantee sustainable exploitation with a high probability. Blue ling CPUE did not always adequately reflect trends in biomass, which mainly resulted from fleet dynamics, possibly in combination with density-dependence. The stock dynamics of roundnose grenadier (Coryphaenoides rupestris), black scabbardfish (Aphanopus carbo) and deepwater sharks (Centrophorus squamosus and Centroscymnus coelolepis) were little affected by the type of HCR chosen to manage blue ling.

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 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.

Declines in populations of Australia's endemic tropical rainforest frogs

1994 ◽  
Vol 1 (1) ◽  
pp. 66 ◽  
Author(s):  
Stephen J. Richards ◽  
Keith R. McDonald ◽  
Ross A. Alford
Keyword(s):  
Tropical Rainforest ◽  
Management Strategies ◽  
Inorganic Ions ◽  
Tropical Rainforests ◽  
Population Declines ◽  
Term Survival ◽  
Feral Pigs ◽  
Frog Species ◽  
History Of

Comparisons of present and past occurrences suggest that populations of six frog species endemic to the tropical rainforests of northern Queensland have declined during the past ten years. Most declines have occurred at high altitudes in the southern portions of the tropical rainforest. An extensive survey conducted during the summer of 1991-1992 did not locate any individuals of two upland species, Litoria nyakalensis and Taudactylus rheophilus. Another upland species, T. acutirostris, which formerly was widely distributed, appears to have declined in rainforests south of the Daintree River. Three species (Litoria nannotis, L. rheocola and Nyctimystes dayi) were absent from most upland sites south of the Daintree River, but were common at lowland sites and at all sites north of the Daintree River. Aspects of water chemistry, including inorganic ions, heavy metals, and pesticide residues, were analysed for many sites. These analyses failed to identify any abnormalities that might have contributed to frog declines. Declines appear to be unrelated to the history of forestry or mining at sites, or to low rainfall in wet seasons. Levels of habitat disturbance by feral pigs appear to have increased at some sites in recent years and, either by this disturbance or through direct predation, feral pigs may have contributed to declines in some populations. However, pigs are unlikely to be the sole cause of frog population declines. Once declines have occurred, fragmentation of rainforest habitats may prevent recolonization from adjacent sites. Until causal agents associated with declines can be identified, management strategies to ensure the long-term survival of these species must involve protection of the riparian habitats in which they occur.

scholarly journals Pituitary Carcinoma: Difficult Diagnosis and Treatment

2011 ◽  
Vol 96 (12) ◽  
pp. 3649-3660 ◽  
Author(s):  
Anthony P. Heaney
Keyword(s):  
Evidence Synthesis ◽  
Management Strategies ◽  
Pituitary Tumors ◽  
Rare Condition ◽  
Pituitary Carcinoma ◽  
Term Survival ◽  
Diagnosis And Management ◽  
Improved Outcomes ◽  
Recent Developments

Context: Although pituitary tumors are common, pituitary carcinoma is very rare and is only diagnosed when pituitary tumor noncontiguous with the sellar region is demonstrated. Diagnosis is difficult, resulting in delays that may adversely effect outcome that is traditionally poor. Barriers to earlier diagnosis and management strategies for pituitary carcinoma are discussed. Evidence Acquisition: PubMed was employed to identify relevant studies, a review of the literature was conducted, and data were summarized and integrated from the author's perspective. Evidence Synthesis: The available data highlight the difficulties in diagnosis and management and practical challenges in conducting clinical trials in this rare condition. They suggest that earlier diagnosis with aggressive multimodal therapy may be advantageous in some cases. Conclusions: Although pituitary carcinoma remains difficult to diagnose and treat, recent developments have led to improved outcomes in selected cases. With broader use of molecular markers, efforts to modify current histopathological criteria for pituitary carcinoma diagnosis may now be possible. This would assist earlier diagnosis and, in combination with targeted therapies, potentially improve long-term survival.

scholarly journals A survey of the Annamese Lowlands, Vietnam, and its implications for the conservation of Vietnamese and Imperial Pheasants Lophura hatinhensis and L. imperialis

1994 ◽  
Vol 4 (4) ◽  
pp. 343-382 ◽  
Author(s):  
Jonathan C. Eames ◽  
Frank R. Lambert ◽  
Nguyen Cu
Keyword(s):  
Protected Area ◽  
Conclusive Evidence ◽  
Conservation Areas ◽  
Hilly Terrain ◽  
Term Survival ◽  
River Watershed ◽  
Closed Canopy ◽  
Logged Forest ◽  
Suitable Area

SummaryDuring June and July 1994, five sites in the Annamese Lowlands Endemic Bird Area weresurveyed for restricted-range and globally threatened birds, with the ultimate aim of identifying a suitable area for protected area establishment to safeguard populations of endemic Lophura pheasants. Vietnamese Pheasant L. hatinhensis was found at twosites situated less than 10 km apart, although only regularly encountered in one area, the Net River watershed, Quang Binh province. No conclusive evidence was found of the existence of Imperial Pheasant L. imperialis at any site, although it almost certainly also occurs in the Net River watershed or close by. Where they occur, logging and hunting pose the most serious threats to the long-term survival of these endemic pheasants. Although previously believed to be largely confined to forest in flatter areas, evidence collected during the surveys suggests that L. hatinhensis is commonest on ridgetops and slopes in areas with relatively undisturbed, closed-canopy forest. Hence, a major recommendation of this study is that conservation areas for this species should include the maximum extent possible of closed-canopy or lightly logged forest that includes hilly terrain as well as lower-lying, flat areas. The most appropriate area for designation as a protected area was identified as forest in the Net River watershed. It is recommended that a full feasibility study for the establishment of such an area be undertaken as a priority, and that meanwhile a moratorium on legal logging activities and efforts to curtail illegal logging and hunting be implemented by Vietnam's Ministry of Forestry.

scholarly journals Life long follow up and management strategies of patients living with native livers after Kasai portoenterostomy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Patrick Ho Yu Chung ◽  
Edwin Kin Wai Chan ◽  
Fanny Yeung ◽  
Albert Chi Yan Chan ◽  
Jennifer Wai Cheung Mou ◽  
...  
Keyword(s):  
Portal Hypertension ◽  
Management Strategies ◽  
Deceased Donor ◽  
Kasai Portoenterostomy ◽  
Term Survival ◽  
Factors Affecting ◽  
Operative Outcomes ◽  
Native Liver

AbstractWe present a 37 years’ experience in the management of biliary atresia (BA) and discuss long-term complications after Kasai portoenterostomy (KPE). A retrospective territory-wide study from 1980 to 2017 on 231 patients with open KPE from three tertiary paediatric surgical centres was performed. Outcome parameters were clearance of jaundice (COJ), native liver survival (NLS) and long-term complications. Factors affecting the operative outcomes were analyzed. The median duration of follow up was 17.5 (IQR: 13.5–22) years. Over 66% of patients became jaundice-freed at 1 year after KPE. Seventy patients (30.3%) received liver transplant (LT) at a median age of 6.2 (IQR: 4.3–8.4) years. The NLS rates at 10 and 20 years were 70.7% and 61.5% respectively with no significant change over the study period. The median age at KPE was 59 (IQR: 49–67) days. KPE performed before 70 days was associated with higher odd ratios for successful drainage but the age of KPE did not have an impact on the long-term NLS. Among all native liver survivors (n = 153), the median bilirubin level was 24 (IQR: 16–36) µmol/L. Portal hypertension (PHT) and recurrent cholangitis were found in 51.6% and 27.5% of them respectively. With a vigilant follow up program, more than 60% of BA patients could remain stable with the disease and achieve long-term survival without LT. Although cholestasis, portal hypertension and recurrent cholangitis are common in long-term NLS, with a comprehensive follow management strategy, they do not always necessitate LT. Our study serves as an example for countries where deceased donor organs are scarce due to very low donation rate.

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