Applying spatially explicit capture–recapture models to estimate black bear density in South Carolina

2019 ◽  
Vol 43 (3) ◽  
pp. 500-507
Author(s):  
Shefali Azad ◽  
Katherine McFadden ◽  
Joseph D. Clark ◽  
Tammy Wactor ◽  
David S. Jachowski
Keyword(s):  
South Carolina ◽  
Black Bear ◽  
Spatially Explicit ◽  
Capture Recapture

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.

Demographic trends of a harvested American black bear population in northwestern South Carolina

Ursus ◽  
2017 ◽  
Vol 28 (1) ◽  
pp. 56-65 ◽  
Author(s):  
Shefali Azad ◽  
Tammy Wactor ◽  
David Jachowski
Keyword(s):  
South Carolina ◽  
Black Bear ◽  
Demographic Trends ◽  
American Black Bear ◽  
American Black

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.

Using spatially‐explicit capture–recapture models to explain variation in seasonal density patterns of sympatric ursids

Ecography ◽  
2018 ◽  
Vol 42 (2) ◽  
pp. 237-248 ◽  
Author(s):  
Jeffrey B. Stetz ◽  
Michael S. Mitchell ◽  
Katherine C. Kendall
Keyword(s):  
Spatially Explicit ◽  
Capture Recapture

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.

Spatially explicit capture-recapture method (SECR, SPACECAP): A new approach to determination of the Amur tiger (Panthera tigris altaica) population density by means of camera-traps

2013 ◽  
Vol 453 (1) ◽  
pp. 365-368 ◽  
Author(s):  
J. A. Hernandez-Blanco ◽  
V. V. Rozhnov ◽  
V. S. Lukarevskiy ◽  
S. V. Naidenko ◽  
M. D. Chistopolova ◽  
...  
Keyword(s):  
Population Density ◽  
Camera Traps ◽  
Spatially Explicit ◽  
Panthera Tigris ◽  
Amur Tiger ◽  
New Approach ◽  
Panthera Tigris Altaica ◽  
Capture Recapture

A SPATIALLY EXPLICIT MODEL, DERIVED FROM DEMOGRAPHIC VARIABLES, TO PREDICT ATTITUDES TOWARD BLACK BEAR RESTORATION

2004 ◽  
Vol 68 (2) ◽  
pp. 223-232 ◽  
Author(s):  
JACOB L. BOWMAN ◽  
BRUCE D. LEOPOLD ◽  
FRANCISCO J. VILELLA ◽  
DUANE A. GILL
Keyword(s):  
Black Bear ◽  
Demographic Variables ◽  
Spatially Explicit ◽  
Explicit Model ◽  
Spatially Explicit Model ◽  
Black Bear Restoration

scholarly journals Using natural marks in a spatially explicit capture-recapture framework to estimate preliminary population density of cryptic endangered wild cattle in Borneo

2019 ◽  
Vol 20 ◽  
pp. e00748
Author(s):  
Penny C. Gardner ◽  
Ian P. Vaughan ◽  
Lucy P. Liew ◽  
Benoît Goossens
Keyword(s):  
Population Density ◽  
Spatially Explicit ◽  
Capture Recapture ◽  
Natural Marks

Estimating population size by spatially explicit capture-recapture

Oikos ◽  
2012 ◽  
Vol 122 (6) ◽  
pp. 918-928 ◽  
Author(s):  
Murray G. Efford ◽  
Rachel M. Fewster
Keyword(s):  
Population Size ◽  
Spatially Explicit ◽  
Capture Recapture
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