scholarly journals A spatially explicit approach for estimating space use and density of common genets

2014 ◽  
Vol 37 (1) ◽  
pp. 23-33
Author(s):  
P. Sarmento ◽  
◽  
J. Cruz ◽  
C. Eira ◽  
C. Fonseca ◽  
...  
Keyword(s):  
Spatial Model ◽  
Environmental Variables ◽  
Camera Trap ◽  
Grid Size ◽  
Future Research ◽  
Spatially Explicit ◽  
Density Estimates ◽  
Closed Population ◽  
Abundance Estimates ◽  
Capture Recapture

Many species that occur at low densities are not accurately estimated using capture–recapture methods as such techniques assume that populations are well–defined in space. To solve this bias, spatially explicit capture–recapture (SECR) models have recently been developed. These models incorporate movement and can identify areas where it is more likely for individuals to concentrate their activity. In this study, we used data from camera–trap surveys of common genets (Genetta genetta) in Serra da Malcata (Portugal), designed to compare abundance estimates produced by SECR models with traditional closed–capture models. Using the SECR models, we observed spatial heterogeneity in genet distribution and density estimates were approximately two times lower than those obtained from the closed population models. The non–spatial model estimates were constrained to sampling grid size and likely underestimated movements, thereby overestimating density. Future research should consider the incorporation of cost–weighed models that can include explicit hypothesis on how environmental variables influence the distance metric.

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 Bringing clarity to the clouded leopard Neofelis diardi: first density estimates from Sumatra

Oryx ◽  
2014 ◽  
Vol 48 (4) ◽  
pp. 536-539 ◽  
Author(s):  
Rahel Sollmann ◽  
Matthew Linkie ◽  
Iding A. Haidir ◽  
David W. Macdonald
Keyword(s):  
Mixed Forest ◽  
Camera Trap ◽  
Forest Loss ◽  
Data Sets ◽  
Panthera Tigris ◽  
Density Estimates ◽  
Clouded Leopard ◽  
Data Limitations ◽  
Capture Recapture ◽  
Study Sites

AbstractWe use data from camera-trap surveys for tigers Panthera tigris in combination with spatial capture–recapture models to provide the first density estimates for the Sunda clouded leopard Neofelis diardi on Sumatra. Surveys took place during 2004–2007 in the Kerinci landscape. Densities were 0.385–1.278 per 100 km2. We found no statistically significant differences in density among four study sites or between primary and mixed forest. Because the data sets are too small to account for differences in detection parameters between sexes, density is probably underestimated. Estimates are comparable to previous estimates of 1–2 per 100 km2 from the lowlands of central Sabah, on Borneo. Data limitations suggest that camera-trap surveys for Sunda clouded leopards require traps spaced more closely, to increase the chance of recaptures at different traps. Nevertheless, these first density estimates for clouded leopards on Sumatra provide a benchmark for measuring future conservation impact on an island that is undergoing rapid forest loss.

scholarly journals Abundance of East coast Australian humpback whales (Megaptera novaeangliae) in 2005 estimated using multi-point sampling and capture-recapture analysis

2020 ◽  
pp. 253-259
Author(s):  
David A. Paton ◽  
Lyndon Brooks ◽  
Daniel Burns ◽  
Trish Franklin ◽  
Wally Franklin ◽  
...  
Keyword(s):  
East Coast ◽  
Megaptera Novaeangliae ◽  
Humpback Whales ◽  
Migration Route ◽  
Closed Population ◽  
Breeding Stock ◽  
Abundance Estimate ◽  
Abundance Estimates ◽  
Capture Recapture ◽  
Near Extinction

The humpback whales (Megaptera novaeangliae) that migrate along the east coast of Australia were hunted to near extinction during the lastcentury. This remnant population is part of Breeding Stock E. Previous abundance estimates for the east Australian portion of Breeding Stock Ehave been based mainly on land-based counts. Here we present a capture-recapture abundance estimate for this population using photo-identificationdata. These data were collected at three locations on the migration route (Byron Bay – northern migration, Hervey Bay and Ballina – southernmigration) in order to estimate the population of humpback whales that migrated along the east coast of Australia in 2005. The capture-recapturedata were analysed using a variety of closed population models with a model-averaged estimate of 7,041 (95% CI 4,075–10,008) whales.

scholarly journals Dingo Density Estimates and Movements in Equatorial Australia: Spatially Explicit Mark–Resight Models

Animals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 865
Author(s):  
Vanessa Gabriele-Rivet ◽  
Julie Arsenault ◽  
Victoria J. Brookes ◽  
Peter J. S. Fleming ◽  
Charlotte Nury ◽  
...  
Keyword(s):  
Home Range ◽  
Spatial Correlation ◽  
Disease Transmission ◽  
Indigenous Communities ◽  
Camera Trap ◽  
Disease Spread ◽  
Spatially Explicit ◽  
Ecological Knowledge ◽  
Northern Australia ◽  
Density Estimates

Australia is currently free of canine rabies. Spatio-ecological knowledge about dingoes in northern Australia is currently a gap that impedes the application of disease spread models and our understanding of the potential transmission of rabies, in the event of an incursion. We therefore conducted a one-year camera trap survey to monitor a dingo population in equatorial northern Australia. The population is contiguous with remote Indigenous communities containing free-roaming dogs, which potentially interact with dingoes. Based on the camera trap data, we derived dingo density and home range size estimates using maximum-likelihood, spatially explicit, mark–resight models, described dingo movements and evaluated spatial correlation and temporal overlap in activities between dingoes and community dogs. Dingo density estimates varied from 0.135 animals/km2 (95% CI = 0.127–0.144) during the dry season to 0.147 animals/km2 (95% CI = 0.135–0.159) during the wet season. The 95% bivariate Normal home range sizes were highly variable throughout the year (7.95–29.40 km2). Spatial use and daily activity patterns of dingoes and free-roaming community dogs, grouped over ~3 month periods, showed substantial temporal activity overlap and spatial correlation, highlighting the potential risk of disease transmission at the wild–domestic interface in an area of biosecurity risk in equatorial northern Australia. Our results have utility for improving preparedness against a potential rabies incursion.

scholarly journals Estimates of density and sustainable harvest of the lowland tapir Tapirus terrestris in the Amazon of French Guiana using a Bayesian spatially explicit capture–recapture model

Oryx ◽  
2013 ◽  
Vol 48 (3) ◽  
pp. 410-419 ◽  
Author(s):  
Mathias W. Tobler ◽  
Fabrice Hibert ◽  
Laure Debeir ◽  
Cécile Richard-Hansen
Keyword(s):  
French Guiana ◽  
Spatially Explicit ◽  
Sustainable Harvest ◽  
Density Estimates ◽  
Calculated Density ◽  
Encounter Rates ◽  
Moist Forest ◽  
Tapirus Terrestris ◽  
Capture Recapture ◽  
Males And Females

AbstractThe Amazonian moist forest, which covers most of French Guiana, is one of the core habitats for the lowland tapir Tapirus terrestris. Tapirs are hunted in French Guiana, although a law introduced in 2011 restricts hunting to one animal per person per hunting trip. We carried out camera-trap surveys in the Nouragues Nature Reserve for 4 years, with the goal of estimating tapir densities in undisturbed conditions and determining sustainable harvest levels for tapirs in French Guiana. We analysed our data with a Bayesian spatially explicit capture–recapture model, with parameter sharing across surveys to improve estimates, and used the model to calculate derived parameters such as maximum sustainable harvest levels. Density estimates for all four surveys were similar and the model indicated a difference in encounter rates for the two camera models used but no difference in encounter rates or home range sizes for males and females or between years. Based on the calculated density of 0.32 tapir km−2 we estimated sustainable harvest levels at 0.009 tapir km−2. Comparing this value to hunting surveys from 11 sites between 1999 and 2006, we found that hunting levels were unsustainable in at least seven villages. We conclude that even the new restrictive hunting law will not prevent overhunting of tapirs in certain areas and thus stronger regulations are needed. However, because of the remoteness of tapir habitat in many parts of French Guiana tapirs are not immediately threatened in the country as a whole.

scholarly journals Leopard Panthera pardus fusca Density in the Seasonally Dry, Subtropical Forest in the Bhabhar of Terai Arc, Nepal

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Kanchan Thapa ◽  
Rinjan Shrestha ◽  
Jhamak Karki ◽  
Gokarna Jung Thapa ◽  
Naresh Subedi ◽  
...  
Keyword(s):  
Winter Season ◽  
Population Monitoring ◽  
Panthera Pardus ◽  
Density Estimates ◽  
Seasonally Dry ◽  
Abundance Estimates ◽  
Capture Recapture ◽  
Modelling Techniques ◽  
Wildlife Reserve

We estimated leopard (Panthera pardus fusca) abundance and density in the Bhabhar physiographic region in Parsa Wildlife Reserve, Nepal. The camera trap grid, covering sampling area of 289 km2 with 88 locations, accumulated 1,342 trap nights in 64 days in the winter season of 2008-2009 and photographed 19 individual leopards. Using models incorporating heterogeneity, we estimated 28 (±SE 6.07) and 29.58 (±SE 10.44) leopards in Programs CAPTURE and MARK. Density estimates via 1/2 MMDM methods were 5.61 (±SE 1.30) and 5.93 (±SE 2.15) leopards per 100 km2 using abundance estimates from CAPTURE and MARK, respectively. Spatially explicit capture recapture (SECR) models resulted in lower density estimates, 3.78 (±SE 0.85) and 3.48 (±SE 0.83) leopards per 100 km2, in likelihood based program DENSITY and Bayesian based program SPACECAP, respectively. The 1/2 MMDM methods have been known to provide much higher density estimates than SECR modelling techniques. However, our SECR models resulted in high leopard density comparable to areas considered better habitat in Nepal indicating a potentially dense population compared to other sites. We provide the first density estimates for leopards in the Bhabhar and a baseline for long term population monitoring of leopards in Parsa Wildlife Reserve and across the Terai Arc.

Continuous-time spatially explicit capture-recapture models, with an application to a jaguar camera-trap survey

2014 ◽  
Vol 5 (7) ◽  
pp. 656-665 ◽  
Author(s):  
David Borchers ◽  
Greg Distiller ◽  
Rebecca Foster ◽  
Bart Harmsen ◽  
Lorenzo Milazzo
Keyword(s):  
Continuous Time ◽  
Camera Trap ◽  
Spatially Explicit ◽  
Capture Recapture

scholarly journals Density trends of wild felids in northern Laos

2021 ◽  
Author(s):  
Akchousanh Rasphone ◽  
Jan F. Kamler ◽  
Mathias Tobler ◽  
David W. Macdonald
Keyword(s):  
National Park ◽  
Community Outreach ◽  
Camera Trap ◽  
Panthera Tigris ◽  
Mesopredator Release ◽  
Density Estimates ◽  
Clouded Leopard ◽  
Capture Recapture ◽  
Leopard Cat ◽  
Prionailurus Bengalensis

AbstractDetermining the density trends of a guild of species can help illuminate their interactions, and the impacts that humans might have on them. We estimated the density trends from 2013 to 2017 of the clouded leopard Neofelis nebulosa, leopard cat Prionailurus bengalensis and marbled cat Pardofelis marmorata in Nam Et—Phou Louey National Park (NEPL), Laos, using camera trap data and spatial capture-recapture models. Mean (± SD) density estimates (individuals/100 km2) for all years were 1.77 ± 0.30 for clouded leopard, 1.50 ± 0.30 for leopard cat, and 3.80 ± 0.70 for marbled cat. There was a declining trend in density across the study years for all three species, with a ≥ 90% probability of decline for clouded leopard and leopard cat and an 83% probability of decline for marbled cat. There was no evidence that mesopredator release occurred as a result of tiger (Panthera tigris) and leopard (P. pardus) extirpations. We believe that snaring, the factor that led to the extirpation of tiger and leopard in NEPL, is now contributing to the decline of smaller felids, to an extent that over-rides any potential effects of mesopredator release on their densities and interactions. We recommend that the NEPL managers implement a more systematic and intensified snare removal program, in concert with extensive community outreach and engagement of local people to prevent the setting of snares. These actions might be the only hope for saving the remaining members of the felid community in NEPL.

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