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Camera Trapping

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Rahel Sollmann – 1st expert on this subject based on the ideXlab platform

  • combining Camera Trapping and noninvasive genetic data in a spatial capture recapture framework improves density estimates for the jaguar
    Biological Conservation, 2013
    Co-Authors: Rahel Sollmann, Natalia Mundim Torres, Mariana Malzoni Furtado, Anah Tereza De Almeida Jacomo, Francisco Palomares, Severine Roques, Leandro Silveira

    Abstract:

    Abstract Abundance and density are key pieces of information for questions related to ecology and conservation. These quantities, however, are difficult to obtain for rare and elusive species, where even intensive sampling effort can yield sparse data. Here, we combine data from CameraTrapping and noninvasive genetic sampling (scat surveys) of a jaguar population in the Caatinga of northeastern Brazil, where the species is threatened and little studied. We analyze data of both survey types separately and jointly in the framework of spatial capture–recapture. Density estimates were 1.45 (±0.46) for the Camera-trap data alone, 2.03 (±0.77) for the genetic data alone, and 1.57 (±0.43) and 2.45 (±0.70) for the two methods, respectively, in the joint analysis. Density and other parameters were estimated more precisely in the joint model. Particularly the differences in movement between males and females were estimated much more precisely when combining both data sources, especially compared to the genetic data set alone. When compared to a previous non-spatial capture–recapture approach, present density estimates were more precise, demonstrating the superior statistical performance of spatial over non-spatial capture recapture models. The ability to combine different surveys into a single analysis with shared parameter allows for more precise population estimates, while at the same time enabling researchers to employ complementary survey techniques in the study of little known species.

  • risky business or simple solution relative abundance indices from Camera Trapping
    Biological Conservation, 2013
    Co-Authors: Rahel Sollmann, Azlan Mohamed, Hiromitsu Samejima, Andreas Wilting

    Abstract:

    Camera-traps are a widely applied to monitor wildlife populations. For individually marked species, capture–recapture models provide robust population estimates, but for unmarked species, inference is often based on relative abundance indices (RAI, number of records per trap effort), although these do not account for imperfect and variable detection. We use a simulation study and empirical CameraTrapping data to illustrate how ecological and sampling-related factors can bias RAIs. Our simulations showed that (1) differences in detection between species led to bias in RAI ratios toward the more detectable species, especially at low detection levels, (2) species with larger home ranges were photographed more often, inflating RAIs, (3) species specific responses to different types of trap setup biased RAI ratios, and (4) changes in detection over time blurred true population trends inferred from RAIs. Empirical data for leopard cats Prionailurus bengalensis and common palm civets Paradoxurus hermaphroditus showed that traps set up along roads led to higher RAIs than off-road traps, but targeting roads increased detection more for leopard cats than for common palm civets. Comparing RAIs of Sunda clouded leopards Neofelis diardi and leopard cats with spatial capture–recapture based density estimates across sites, RAIs did not reflect differences in density. Analytical options for estimating density from CameraTrapping data of unmarked populations are limited. Consequently, we fear that RAIs will continue to be applied. This is alarming, since these measures often form the basis for conservation and management decisions. We suggest considering alternative analytical and survey methods, especially when dealing with threatened species.

  • Risky business or simple solution – Relative abundance indices from CameraTrapping
    Biological Conservation, 2013
    Co-Authors: Rahel Sollmann, Azlan Mohamed, Hiromitsu Samejima, Andreas Wilting

    Abstract:

    Camera-traps are a widely applied to monitor wildlife populations. For individually marked species, capture-recapture models provide robust population estimates, but for unmarked species, inference is often based on relative abundance indices (RAI, number of records per trap effort), although these do not account for imperfect and variable detection. We use a simulation study and empirical CameraTrapping data to illustrate how ecological and sampling-related factors can bias RAIs. Our simulations showed that (1) differences in detection between species led to bias in RAI ratios toward the more detectable species, especially at low detection levels, (2) species with larger home ranges were photographed more often, inflating RAIs, (3) species specific responses to different types of trap setup biased RAI ratios, and (4) changes in detection over time blurred true population trends inferred from RAIs. Empirical data for leopard cats Prionailurus bengalensis and common palm civets Paradoxurus hermaphroditus showed that traps set up along roads led to higher RAIs than off-road traps, but targeting roads increased detection more for leopard cats than for common palm civets. Comparing RAIs of Sunda clouded leopards Neofelis diardi and leopard cats with spatial capture-recapture based density estimates across sites, RAIs did not reflect differences in density. Analytical options for estimating density from CameraTrapping data of unmarked populations are limited. Consequently, we fear that RAIs will continue to be applied. This is alarming, since these measures often form the basis for conservation and management decisions. We suggest considering alternative analytical and survey methods, especially when dealing with threatened species. © 2012 Elsevier Ltd.

Andreas Wilting – 2nd expert on this subject based on the ideXlab platform

  • risky business or simple solution relative abundance indices from Camera Trapping
    Biological Conservation, 2013
    Co-Authors: Rahel Sollmann, Azlan Mohamed, Hiromitsu Samejima, Andreas Wilting

    Abstract:

    Camera-traps are a widely applied to monitor wildlife populations. For individually marked species, capture–recapture models provide robust population estimates, but for unmarked species, inference is often based on relative abundance indices (RAI, number of records per trap effort), although these do not account for imperfect and variable detection. We use a simulation study and empirical CameraTrapping data to illustrate how ecological and sampling-related factors can bias RAIs. Our simulations showed that (1) differences in detection between species led to bias in RAI ratios toward the more detectable species, especially at low detection levels, (2) species with larger home ranges were photographed more often, inflating RAIs, (3) species specific responses to different types of trap setup biased RAI ratios, and (4) changes in detection over time blurred true population trends inferred from RAIs. Empirical data for leopard cats Prionailurus bengalensis and common palm civets Paradoxurus hermaphroditus showed that traps set up along roads led to higher RAIs than off-road traps, but targeting roads increased detection more for leopard cats than for common palm civets. Comparing RAIs of Sunda clouded leopards Neofelis diardi and leopard cats with spatial capture–recapture based density estimates across sites, RAIs did not reflect differences in density. Analytical options for estimating density from CameraTrapping data of unmarked populations are limited. Consequently, we fear that RAIs will continue to be applied. This is alarming, since these measures often form the basis for conservation and management decisions. We suggest considering alternative analytical and survey methods, especially when dealing with threatened species.

  • Risky business or simple solution – Relative abundance indices from CameraTrapping
    Biological Conservation, 2013
    Co-Authors: Rahel Sollmann, Azlan Mohamed, Hiromitsu Samejima, Andreas Wilting

    Abstract:

    Camera-traps are a widely applied to monitor wildlife populations. For individually marked species, capture-recapture models provide robust population estimates, but for unmarked species, inference is often based on relative abundance indices (RAI, number of records per trap effort), although these do not account for imperfect and variable detection. We use a simulation study and empirical CameraTrapping data to illustrate how ecological and sampling-related factors can bias RAIs. Our simulations showed that (1) differences in detection between species led to bias in RAI ratios toward the more detectable species, especially at low detection levels, (2) species with larger home ranges were photographed more often, inflating RAIs, (3) species specific responses to different types of trap setup biased RAI ratios, and (4) changes in detection over time blurred true population trends inferred from RAIs. Empirical data for leopard cats Prionailurus bengalensis and common palm civets Paradoxurus hermaphroditus showed that traps set up along roads led to higher RAIs than off-road traps, but targeting roads increased detection more for leopard cats than for common palm civets. Comparing RAIs of Sunda clouded leopards Neofelis diardi and leopard cats with spatial capture-recapture based density estimates across sites, RAIs did not reflect differences in density. Analytical options for estimating density from CameraTrapping data of unmarked populations are limited. Consequently, we fear that RAIs will continue to be applied. This is alarming, since these measures often form the basis for conservation and management decisions. We suggest considering alternative analytical and survey methods, especially when dealing with threatened species. © 2012 Elsevier Ltd.

Andrew J Noss – 3rd expert on this subject based on the ideXlab platform

  • brazilian tapir density in the pantanal a comparison of systematic Camera Trapping and line transect surveys
    Biotropica, 2008
    Co-Authors: Mogens Trolle, Andrew J Noss, Jose Luis Passos Cordeiro, Luiz Flamarion B Oliveira

    Abstract:

    The density of Brazilian tapirs (Tapirus terrestris) was studied in the northeastern part of the Pantanal wetlands of Brazil using two simultaneous and independent methods: (1) systematic Camera Trapping combined with capture–recapture analysis, with Camera traps spaced 1 km apart and distributed over 54 km2; and (2) line-transect sampling using an array of 12 linear transects, from 3.8 to 7.2 km long, covering the principal open and forest habitat types across the entire 1063 km2 SESC Pantanal Reserve. The two methods yielded conservative density estimates of 0.58 ± 0.11 tapirs/km2 (Camera Trapping) and 0.55 (95% CI 0.30–1.01) tapirs/km2 (line transects). The study suggests that certain Pantanal habitats and sites can sustain relatively high population densities of tapirs when these animals are protected from hunting. Further testing of the CameraTrapping methodology as applied to tapirs is required, particularly focusing on extending the survey period. As it represents a relatively rapid method for estimating population density, in comparison to line-transect surveys, and as it generates information simultaneously on multiple species that are conservation priorities, we recommend that CameraTrapping surveys be applied more widely across a variety of Pantanal habitats and land-use categories in order to confirm the value of the vast 140,000 km2 wilderness region for this vulnerable species.

    RESUMO

    A densidade de Tapirus terrestris foi avaliada na regiao Nordeste do Pantanal do Mato Grosso usando dois metodos simultâneos e independentes: 1) metodo sistematico com armadilhas fotograficas, combinado com analises de captura e recaptura, com câmaras fotograficas espacadas 1 km entre si e distribuidas sobre uma area de 54 km2, dispostas em 4 grades continuas, com 14 câmaras ativas por 9 dias consecutivos em cada grade; e 2) 12 transeccoes lineares variando em dimensoes de 3,8–7,2 km de extensao, cobrindo os principais habitats abertos e fechados, sobre uma regiao de 1063 km2 da Reserva Particular do Patrimonio Natural SESC Pantanal. Os dois metodos resultaram em estimativas de densidade de 0.58 ± 0.11 antas/km2 (câmaras fotograficas) e 0.55 (95% intervalo de confianca 0.30–1.01) antas/km2 (transeccoes lineares). Os resultados sugerem que certos habitats e areas do Pantanal podem sustentar densidades relativamente elevadas de antas, quando protegidas da caca. A metodologia utilizando câmaras fotograficas em estudos sobre antas deve ser testada incrementando periodos de avaliacao. Como o metodo representa uma forma rapida de avaliacao das densidades populacionais, em comparacao com transeccoes lineares, e gera informacoes simultâneas sobre multiplas especies que podem ser prioritarias para conservacao, recomendamos que avaliacoes com armadilhas fotograficas sejam amplamente aplicadas para a especie na variedade de habitats do Pantanal, visando afirmar o valor dessa vasta e selvagem regiao de 140.000 km2.

  • geoffroy s cats at the northern limit of their range activity patterns and density estimates from Camera Trapping in bolivian dry forests
    Studies on Neotropical Fauna and Environment, 2006
    Co-Authors: Erika Cuellar, Leonardo Maffei, Rosario L Arispe, Andrew J Noss

    Abstract:

    We used Camera traps to survey Geoffroy’s cats, Oncifelis geoffroyi, at six dry forest sites in Bolivia. Cumulative activity patterns across all sites are principally nocturnal though the species is active by day in both summer and winter. At two sites the number of captures and recaptures was sufficient to estimate abundance using the software Capture, and in turn a population density of 9–40 per 100 km2 for the two sites. Geoffroy’s cats are present in all dry forest types surveyed: Chaco savannas, Chaco dry forest, Chaco transitional forest, Chaco‐Chiquitano transitional forest, Chaco‐Cerrado transitional forest and Chiquitano dry forest. They are most abundant at the driest site, the only one with grassland formations and where ocelots are absent. Camera Trapping records tend to be more numerous in the dry season, suggesting seasonal changes in behavior and habitat use. Resumen Empleamos trampas‐camara para muestrear Oncifelis geoffroyi en seis sitios ubicados en bosques secos de Bolivia. El patron de…

  • ocelot felis pardalis population densities activity and ranging behaviour in the dry forests of eastern bolivia data from Camera Trapping
    Journal of Tropical Ecology, 2005
    Co-Authors: Leonardo Maffei, Andrew J Noss, Erika Cuellar, Damian I Rumiz

    Abstract:

    In comparison with the Neotropical big cats, jaguar ( Panthera onca L.) and puma ( Felis concolor L.), medium and small felids are poorly studied. Furthermore, studying wild felids in forest habitats is extremely difficult using direct methods given that most species are principally nocturnal and secretive (Gittleman 1996). Indirect methods are therefore particularly important, e.g. radio-telemetry (Emmons 1987, 1988; Konecny 1989, Ludlow & Sunquist 1987) or Camera Trapping (Maffei et al . 2002, Trolle & Kery 2003). Using systematic Camera trap surveys, we compare the population density of ocelots ( Felis pardalis L.) across five Bolivian dry-forest sites with different habitat types and/or annual rainfall regimes (Table 1). We hypothesize that ocelot densities will decline as rainfall declines. In addition, we estimate the population of ocelots in the 34 400-km 2 Kaa-Iya del Gran Chaco National Park. Finally, we describe and evaluate additional ecological information provided by Camera Trapping: activity patterns relative to seasonality and moon phase, sex ratios, ranging patterns and relative abundance compared with sympatric felids.