FIELD COMPARISON OF REMOVAL AND MODIFIED DOUBLE-OBSERVER MODELING FOR ESTIMATING DETECTABILITY AND ABUNDANCE OF BIRDS

The Auk ◽  
2004 ◽  
Vol 121 (3) ◽  
pp. 865 ◽  
Author(s):  
Jeffrey E. Moore ◽  
Daniel M. Scheiman ◽  
Robert K. Swihart
Keyword(s):  
Double Observer

A double-observer method for reducing bias in faecal pellet surveys of forest ungulates

2008 ◽  
Vol 45 (5) ◽  
pp. 1339-1348 ◽  
Author(s):  
K. J. Jenkins ◽  
B. F. J. Manly
Keyword(s):  
Faecal Pellet ◽  
Double Observer

scholarly journals Dependent double‐observer method reduces false‐positive errors in auditory avian survey data

2019 ◽  
Vol 30 (2) ◽  
Author(s):  
Kaitlyn M. Strickfaden ◽  
Danielle A. Fagre ◽  
Jessie D. Golding ◽  
Alan H. Harrington ◽  
Kaitlyn M. Reintsma ◽  
...  
Keyword(s):  
Survey Data ◽  
False Positive ◽  
Double Observer

scholarly journals Population assessment of the Endangered Nilgiri tahr Nilgiritragus hylocrius in the Anamalai Tiger Reserve, using the double-observer survey method

Oryx ◽  
2020 ◽  
pp. 1-7
Author(s):  
Kulbhushansingh Ramesh Suryawanshi ◽  
Divya Mudappa ◽  
Munib Khanyari ◽  
T. R. Shankar Raman ◽  
Devika Rathore ◽  
...  
Keyword(s):  
Western Ghats ◽  
Survey Method ◽  
Tropical Mountains ◽  
Tiger Reserve ◽  
Western Ghats Of India ◽  
Global Population ◽  
Term Monitoring ◽  
The Western Ghats ◽  
Double Observer

Abstract The Nilgiri tahr Nilgiritragus hylocrius is an Endangered species of mountain ungulate endemic to the Western Ghats of India, a biodiversity hotspot. Habitat fragmentation, hunting and a restricted range are the major threats to this species. Although several surveys have assessed the species’ status, a population estimate based on a scientifically robust method is needed. We used the double-observer method to estimate the population of the Nilgiri tahr in the Anamalai Tiger Reserve, a protected area in the Western Ghats. We walked 257 km of transects across the Reserve, covering 36 grassland blocks (i.e. clusters of montane grasslands that were relatively separate from each other). We counted a minimum of 422 individuals in 28 groups, and estimated the tahr population in the study area to be 510 individuals (95% CI 300–858) in 35 groups. The male:female ratio was 0.71 and the young:female ratio was 0.56. Comparing our estimate with previous surveys suggests that the Nilgiri tahr population in Anamalai Tiger Reserve is stable. We found the double-observer survey method to be appropriate for population estimation and long-term monitoring of this species, and make recommendations for improved field protocols to facilitate the implementation of the method in the tropical mountains of the Western Ghats. Our findings suggest that the Reserve harbours 20–25% of the global population of the Nilgiri tahr, highlighting the area's importance for the conservation of this species.

scholarly journals Double-Observer Line Transect Methods: Levels of Independence

Biometrics ◽  
2009 ◽  
Vol 66 (1) ◽  
pp. 169-177 ◽  
Author(s):  
Stephen T. Buckland ◽  
Jeffrey L. Laake ◽  
David L. Borchers
Keyword(s):  
Line Transect ◽  
Double Observer

Field Comparison of Removal and Modified Double-Observer Modeling for Estimating Detectability and Abundance of Birds

The Auk ◽  
2004 ◽  
Vol 121 (3) ◽  
pp. 865-876 ◽  
Author(s):  
Jeffrey E. Moore ◽  
Daniel M. Scheiman ◽  
Robert K. Swihart
Keyword(s):  
Double Observer

scholarly journals Estimating Detection Probability and Density from Point-Count Surveys: A Combination of Distance and Double-Observer Sampling

The Auk ◽  
2006 ◽  
Vol 123 (3) ◽  
pp. 735-752 ◽  
Author(s):  
Michelle L. Kissling ◽  
Edward O. Garton
Keyword(s):  
Detection Probability ◽  
Survey Methods ◽  
Effective Area ◽  
Survey Method ◽  
Density Estimates ◽  
Point Count ◽  
Detection Probabilities ◽  
Fixed Radius ◽  
Count Surveys ◽  
Double Observer

Abstract Point counts are the method most commonly used to estimate abundance of birds, but they often fail to account properly for incomplete and variable detection probabilities. We developed a technique that combines distance and double-observer sampling to estimate detection probabilities and effective area surveyed. We applied this paired-observer, variable circular-plot (POVCP) technique to point-count surveys (n = 753) conducted in closed-canopy forests of southeast Alaska. Distance data were analyzed for each species to model a detection probability for each observer and calculate an estimate of density. We then multiplied each observer's density estimates by a correction factor to adjust for detection probabilities <1 at plot center. We compared analytical results from four survey methods: single-observer fixed-radius (50-m) plot; single-observer, variable circular-plot (SOVCP); double-observer fixed-radius (50-m) plot; and POVCP. We examined differences in detection probabilities at plot center, effective area surveyed, and densities for five bird species: Pacific-slope Flycatcher (Empidonax difficilis), Winter Wren (Troglodytes troglodytes), Golden-crowned Kinglet (Regulus satrapa), Hermit Thrush (Catharus guttatus), and Townsend's Warbler (Dendroica townsendi). Average detection probabilities for paired observers increased ≈8% (SE = 2.9) for all species once estimates were corrected for birds missed at plot center. Density estimators of fixed-radius survey methods were likely negatively biased, because the key assumption of perfect detection was not met. Density estimates generated using SOVCP and POVCP were similar, but standard errors were much lower for the POVCP survey method. We recommend using POVCP when study objectives require precise estimates of density. Failure to account for differences in detection probabilities and effective area surveyed results in biased population estimators and, therefore, faulty inferences about the population in question. Estimaciones de la Densidad y de las Probabilidades de Detección a Partir de Muestreos Utilizando Conteos en Puntos: Una Combinación de Muestreos de Distancia y de Doble Observador

scholarly journals A New Double Sliding Mode Observer for EV Lithium Battery SOC Estimation

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Qiaoyan Chen ◽  
Jiuchun Jiang ◽  
Haijun Ruan ◽  
Caiping Zhang
Keyword(s):  
Sliding Mode ◽  
Internal Resistance ◽  
Sliding Mode Observer ◽  
Working Process ◽  
First Order ◽  
Soc Estimation ◽  
Battery Model ◽  
Ohmic Resistance ◽  
Remaining Capacity ◽  
Double Observer

A new sliding mode observer is proposed in this paper; compared with the existing sliding mode observer used for SOC estimation, the new observer has the advantages of simple design and good generality. The robustness of the new observer was proved by Lyapunov stability theorem. Taking the first-order Randle circuit model of the battery as an example, the new sliding mode observer was designed. Battery test was done with the simulated FUDS condition, and the robustness of the new observer was verified by the test. Because battery internal ohmic resistance is changing in battery working process, which has a significant effect on SOC estimation, a new double sliding mode observer was designed to identify the internal resistance. The tests results show that the battery internal ohmic resistance changes greatly when the SOC is low and the double observer can accurately identify the resistance which improves the accuracy of the battery model. The results also show that the new double observer is robust and can improve the precision of SOC estimation when the battery remaining capacity is low.

scholarly journals Correction: A Unimodal Model for Double Observer Distance Sampling Surveys

PLoS ONE ◽  
2015 ◽  
Vol 10 (10) ◽  
pp. e0140913
Author(s):  
Earl F. Becker ◽  
Aaron M. Christ
Keyword(s):  
Distance Sampling ◽  
Double Observer
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