scholarly journals Estimating animal abundance and effort–precision relationship with camera trap distance sampling

Ecosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Noémie Cappelle ◽  
Eric J. Howe ◽  
Christophe Boesch ◽  
Hjalmar S. Kühl
Keyword(s):  
Distance Sampling ◽  
Camera Trap ◽  
Animal Abundance

scholarly journals Simultaneous Modelling of Movement, Measurement Error, and Observer Dependence in Double-Observer Distance Sampling Surveys

2017 ◽  
Author(s):  
By Paul B. Conn ◽  
Ray T. Alisauskas
Keyword(s):  
Measurement Error ◽  
Detection Probability ◽  
Marginal Likelihood ◽  
Distance Sampling ◽  
Mark Recapture ◽  
Animal Groups ◽  
Animal Abundance ◽  
Helicopter Survey ◽  
Using Data ◽  
Double Observer

Mark-recapture distance sampling uses detections, non-detections and recorded distances of animals encountered in transect surveys to estimate abundance. However, commonly available distance sampling estimators require that distances to target animals are made without error and that animals are stationary while sampling is being conducted. In practice these requirements are often violated. In this paper, we describe a marginal likelihood framework for estimating abundance from double-observer data that can accommodate movement and measurement error when observations are made consecutively (as with front and rear observers) and when animals are randomly distributed when detected by the first observer. Our framework requires that two observers independently detect and record binned distances to observed animal groups, as we well as a binary indicator for whether animals were moving or not. We then assume that stationary animals are subject to measurement error whereas moving animals are subject to both movement and measurement error. Integrating over unknown animal locations, we construct a marginal likelihood for detection, movement, and measurement error parameters. Estimates of animal abundance are then obtained using a modified Horvitz-Thompson-like estimator. In addition, unmodelled heterogeneity in detection probability can be accommodated through observer dependence parameters. Using simulation, we show that our approach yields low bias compared to approaches that ignore movement and/or measurement error, including in cases where there is considerable detection heterogeneity. We demonstrate our approach using data from a double-observer waterfowl helicopter survey.

Validating camera trap distance sampling for chimpanzees

2019 ◽  
Vol 81 (3) ◽  
pp. e22962 ◽  
Author(s):  
Noémie Cappelle ◽  
Marie‐Lyne Després‐Einspenner ◽  
Eric J. Howe ◽  
Christophe Boesch ◽  
Hjalmar S. Kühl
Keyword(s):  
Distance Sampling ◽  
Camera Trap

scholarly journals Evaluating the status of the Endangered tiger Panthera tigris and its prey in Panna Tiger Reserve, Madhya Pradesh, India

Oryx ◽  
2010 ◽  
Vol 44 (3) ◽  
pp. 383-389 ◽  
Author(s):  
Rajesh Gopal ◽  
Qamar Qureshi ◽  
Manish Bhardwaj ◽  
R.K. Jagadish Singh ◽  
Yadvendradev V. Jhala
Keyword(s):  
Distance Sampling ◽  
Camera Trap ◽  
Madhya Pradesh ◽  
Suitable Habitat ◽  
Panthera Tigris ◽  
Single Male ◽  
Tiger Reserve ◽  
The Status ◽  
Local Extinctions ◽  
Tiger Population

AbstractWe evaluated the status of tigers Panthera tigris and their prey in Panna Tiger Reserve using occupancy surveys, camera-trap mark-recapture population estimation, and distance sampling along foot transects, in 2006. Forest Range tiger occupancy in the Panna landscape (3,500 km2) estimated by 1,077 surveys of 5 km each was 29% ± SE 1. Within occupied Ranges of the Reserve a mean of 68% ± SE 7 of forest Beats had tiger signs. A total of 800 camera-trap nights yielded 24 captures of seven individual adult tigers within an effective trap area of 185.0 ± SE 15.8 km-2. The best model incorporating individual heterogeneity (Mh) estimated the tiger population to be 9 ± SE 2. Tiger density was 4.9 ± SE 1.5 per 100 km2 and was lower than that reported in 2002 (6.49 tigers per 100 km2). Both occupancy and density indicated a decline of the tiger population in the Reserve. Mean ungulate density was 42.4 ± SE 8.4 km-2 and comparable to other tiger reserves. Since our survey in 2006 tiger status in Panna has deteriorated further because of poaching. Panna was occupied by dacoits in late 2006 and anti-insurgent activities caused further disturbances. In late 2008 there was a single male tiger left in Panna but he has not been seen since January 2009. The Madhya Pradesh Forest department has reintroduced three tigers to Panna from neighbouring tiger reserves. Panna, along with Sariska Tiger Reserve, exemplifies the vulnerability of small, isolated tiger populations to local extinctions caused by poaching, even in areas with suitable habitat and sufficient prey.

scholarly journals Drawn out of the shadows: Surveying secretive forest species with camera trap distance sampling

2020 ◽  
Vol 57 (5) ◽  
pp. 963-974 ◽  
Author(s):  
Mattia Bessone ◽  
Hjalmar S. Kühl ◽  
Gottfried Hohmann ◽  
Ilka Herbinger ◽  
Kouame Paul N'Goran ◽  
...  
Keyword(s):  
Distance Sampling ◽  
Camera Trap ◽  
Forest Species

scholarly journals A field test of unconventional camera trap distance sampling to estimate abundance of marmot populations

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
Luca Corlatti ◽  
Stefano Sivieri ◽  
Bogna Sudolska ◽  
Stefano Giacomelli ◽  
Luca Pedrotti
Keyword(s):  
Field Test ◽  
Distance Sampling ◽  
Camera Trap

scholarly journals Accessing camera trap survey feasibility for estimating Blastocerus dichotomus (Cetartiodactyla, Cervidae) demographic parameters

2017 ◽  
Vol 107 (0) ◽  
Author(s):  
Pedro Henrique F. Peres ◽  
Maxihilian S. Polverini ◽  
Márcio L. Oliveira ◽  
José Maurício B. Duarte
Keyword(s):  
Distance Sampling ◽  
Cost Benefit ◽  
Camera Trap ◽  
Camera Traps ◽  
Biological Information ◽  
Individual Identification ◽  
Conservation Strategies ◽  
Observation Data ◽  
Demographic Information ◽  
Blastocerus Dichotomus

ABSTRACT Demographic information is the basis for evaluating and planning conservation strategies for an endangered species. However, in numerous situations there are methodological or financial limitations to obtain such information for some species. The marsh deer, an endangered Neotropical cervid, is a challenging species to obtain biological information. To help achieve such aims, the study evaluated the applicability of camera traps to obtain demographic information on the marsh deer compared to the traditional aerial census method. Fourteen camera traps were installed for three months on the Capão da Cruz floodplain, in state of São Paulo, and ten helicopter flyovers were made along a 13-kilometer trajectory to detect resident marsh deer. In addition to counting deer, the study aimed to identify the sex, age group and individual identification of the antlered males recorded. Population estimates were performed using the capture-mark-recapture method with the camera trap data and by the distance sampling method for aerial observation data. The costs and field efforts expended for both methodologies were calculated and compared. Twenty independent photographic records and 42 sightings were obtained and generated estimates of 0.98 and 1.06 ind/km², respectively. In contrast to the aerial census, camera traps allowed us to individually identify branch-antlered males, determine the sex ratio and detect fawns in the population. The cost of camera traps was 78% lower but required 20 times more field effort. Our analysis indicates that camera traps present a superior cost-benefit ratio compared to aerial surveys, since they are more informative, cheaper and offer simpler logistics. Their application extends the possibilities of studying a greater number of populations in a long-term monitoring.

scholarly journals Estimating tiger and its prey abundance in Bardia National Park, Nepal

2016 ◽  
Vol 26 (1) ◽  
pp. 60-69
Author(s):  
J. B. Karki ◽  
Y. V. Jhala ◽  
B. Pandav ◽  
S. R. Jnawali ◽  
R. Shrestha ◽  
...  
Keyword(s):  
National Park ◽  
Distance Sampling ◽  
Camera Trap ◽  
Prey Abundance ◽  
Sampling Effort ◽  
Mark Recapture ◽  
Line Transects

We estimated tiger and wild prey abundance in the Bardia National Park of Nepal. Tiger abundance was estimated from camera trap mark recapture in 85 days between December, 2008 to March, 2009 by placing 50 camera trap pairs in 197 trap locations with a sampling effort of 2,944 trap nights. We photo captured 16 individuals (≥1.5 year old) tigers identified on the basis of their unique stripe patterns. The number and density (per 100 km2) of tiger was 19 (SE 3.3) and 1.31 (SE 0.32), respectively. Distance sampling was used to assess the prey abundance on 170 systematically laid line transects between May–June, 2009. The density of all the wild prey (individuals/km2) was 56.3 (SE 6.5). The density (individuals/km2Banko JanakariA Journal of Forestry Information for NepalVol. 26, No. 1, Page:  60-69, 2016

scholarly journals Identification errors in camera-trap studies result in systematic population overestimation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Örjan Johansson ◽  
Gustaf Samelius ◽  
Ewa Wikberg ◽  
Guillaume Chapron ◽  
Charudutt Mishra ◽  
...  
Keyword(s):  
Endangered Species ◽  
Camera Trap ◽  
Population Abundance ◽  
Animal Abundance ◽  
Controlled Conditions ◽  
Abundance Estimates ◽  
Snow Leopards ◽  
Conservation Of Endangered Species ◽  
Global Population ◽  
Panthera Uncia

AbstractReliable assessments of animal abundance are key for successful conservation of endangered species. For elusive animals with individually-unique markings, camera-trap surveys are a benchmark standard for estimating local and global population abundance. Central to the reliability of resulting abundance estimates is the assumption that individuals are accurately identified from photographic captures. To quantify the risk of individual misidentification and its impact on population abundance estimates we performed an experiment under controlled conditions in which 16 captive snow leopards (Panthera uncia) were camera-trapped on 40 occasions and eight observers independently identified individuals and recaptures. Observers misclassified 12.5% of all capture occasions, resulting in systematically inflated population abundance estimates on average by one third (mean ± SD = 35 ± 21%). Our results show that identifying individually-unique individuals from camera-trap photos may not be as reliable as previously believed, implying that elusive and endangered species could be less abundant than current estimates indicate.

scholarly journals Deriving observation distances for camera trap distance sampling

2022 ◽  
Author(s):  
Annika M. Zuleger ◽  
Ruben Holland ◽  
Hjalmar S. Kühl
Keyword(s):  
Distance Sampling ◽  
Camera Trap
Sign in / Sign up

Export Citation Format

Share Document