Absolute Population Estimates Using Capture–Recapture Experiments

Author(s):  
Peter A. Henderson

The main methods used to estimate population size using capture–recapture for both closed and open populations are described, including the Peterson–Lincoln estimator, the Schabel census, Bailey’s triple catch, the Jolly–Seber stochastic method, and Cormack’s log-linear method. The robust design approach is described. R code listings for commonly used packages are presented. The assumptions common to capture–recapture methods are reviewed, and tests for assumptions such as equal catchability described. The use of programs to select model assumptions are described. The main methods for marking different animal groups are described, together with the use of natural marks and parasites and DNA. Marking methods include paint marks, dyes, tagging, protein marking, DNA, natural marks, tattooing, and mutilation. Methods for handling and release are described.

Oryx ◽  
2011 ◽  
Vol 45 (1) ◽  
pp. 112-118 ◽  
Author(s):  
Özgün Emre Can ◽  
İrfan Kandemi̇r ◽  
İnci̇ Togan

AbstractThe wildcat Felis silvestris is a protected species in Turkey but the lack of information on its status is an obstacle to conservation initiatives. To assess the status of the species we interviewed local forestry and wildlife personnel and conducted field surveys in selected sites in northern, eastern and western Turkey during 2000–2007. In January–May 2006 we surveyed for the wildcat using 16 passive infrared-trigged camera traps in Yaylacı k Research Forest, a 50-km2 forest patch in Yenice Forest in northern Turkey. A total sampling effort of 1,200 camera trap days over 40 km2 yielded photo-captures of eight individual wildcats over five sampling occasions. Using the software MARK to estimate population size the closed capture–recapture model M0, which assumes a constant capture probability among all occasions and individuals, best fitted the capture history data. The wildcat population size in Yaylacı k Research Forest was estimated to be 11 (confidence interval 9–23). Yenice Forest is probably one of the most important areas for the long-term conservation of the wildcat as it is the largest intact forest habitat in Turkey with little human presence, and without human settlements, and with a high diversity of prey species. However, it has been a major logging area and is not protected. The future of Yenice Forest and its wildcat population could be secured by granting this region a protection status and enforcing environmental legislation.


The Condor ◽  
2004 ◽  
Vol 106 (4) ◽  
pp. 720-731 ◽  
Author(s):  
William L. Kendall ◽  
James D. Nichols

Abstract The estimation of dispersal and movement is important to evolutionary and population ecologists, as well as to wildlife managers. We review statistical methodology available to estimate movement probabilities. We begin with cases where individual birds can be marked and their movements estimated with the use of multisite capture-recapture methods. Movements can be monitored either directly, using telemetry, or by accounting for detection probability when conventional marks are used. When one or more sites are unobservable, telemetry, band recoveries, incidental observations, a closed- or open-population robust design, or partial determinism in movements can be used to estimate movement. When individuals cannot be marked, presence-absence data can be used to model changes in occupancy over time, providing indirect inferences about movement. Where abundance estimates over time are available for multiple sites, potential coupling of their dynamics can be investigated using linear cross-correlation or nonlinear dynamic tools. Sobre la Estimación de la Dispersión y el Movimiento de las Aves Resumen. La estimación de la dispersión y el movimiento es importante para los ecó logos evolutivos y de poblaciones, así como también para los encargados del manejo de vida silvestre. Revisamos la metodología estadística disponible para estimar probabilidades de movimiento. Empezamos con casos donde aves individuales pueden ser marcadas y sus movimientos estimados con el uso de métodos de captura-repactura para múltiples sitios. Los movimientos pueden ser monitoreados ya sea directamente, usando telemetría o teniendo en cuenta las probabilidades de detección cuando se usan marcas convencionales. Cuando uno o más sitios no pueden ser observados, se puede estimar el movimiento usando telemetría, recuperación de anillos, observaciones circunstanciales, un diseño poblacional robusto cerrado o abierto, o determinismo parcial de los movimientos. Cuando los individuos no pueden ser marcados, se pueden usar datos de presencia-ausencia para modelar los cambios en el tiempo de la ocupación, brindando inferencias indirectas sobre los movimientos. Cuando las estimaciones de abundancia a lo largo del tiempo están disponibles para varios sitios, se puede investigar la interrelación potencial de sus dinámicas usando correlaciones cruzadas lineales o herramientas para dinámica no lineal.


2020 ◽  
Vol 82 (6) ◽  
pp. 396-401
Author(s):  
Michael Calver ◽  
Timothy Blake

Estimating population size is essential for many applications in population ecology, so capture–recapture techniques to do this are often taught in secondary school classrooms and introductory university units. However, few classroom simulations of capture–recapture consider the sensitivity of results to sampling intensity, the important concept that the population size calculated is an estimate with error attached, or the consequences of violating assumptions underpinning particular capture–recapture models. We describe a simple approach to teaching the Lincoln index method of capture–recapture using packs of playing cards. Students can trial different sampling intensities, calculate 95% confidence intervals for population estimates, and explore the consequences of violating specific assumptions.


2011 ◽  
Vol 33 (2) ◽  
pp. 228
Author(s):  
Karl Vernes ◽  
Stuart Green ◽  
Piers Thomas

We undertook surveys of brush-tailed rock-wallabies (Petrogale penicillata) at four colonies in Oxley Wild Rivers National Park, north-eastern New South Wales, with the aim of developing a technique based upon individual animal recognition that could be used to obtain robust population estimates for rock-wallaby colonies. We identified individuals on the basis of distinct morphological characters in each colony using visual observations, and used the data within a ‘mark–recapture’ (or sight–resight) framework to estimate population size. More than 37 h of observations were made over 10 sampling days between 18 May and 9 June 2010. We could identify 91.7% of all rock-wallabies that were independently sighted (143 of 156 sightings of 35 animals). A small percentage of animals could not be identified during a visit because they were seen only fleetingly, were in dense cover, or were partly obscured by rock. The number of new animals sighted and photographed declined sharply at the midpoint of the survey, and there was a corresponding increase in resighting of known individuals. Population estimates using the mark–recapture methodology were nearly identical to estimates of total animals seen, suggesting that this method was successful in obtaining a complete census of rock-wallabies in each colony.


2017 ◽  
Vol 10 (13) ◽  
pp. 390
Author(s):  
Priyanka Sharma ◽  
M Janaki Meena ◽  
S P Syed Ibrahim

The objective of current study is to compare a new model for media mix problem with popular model named as simple log linear model. A modified approach proposed to improve the results of media mix model from simple log linear method includes the simultaneous effect of different media variables on sales. The combined effect caused by various media variables shows a synergy in the curve for sales and hence considering it makes the model much effective and accurate.


2016 ◽  
Vol 46 (2) ◽  
pp. 137-143 ◽  
Author(s):  
Juan Marcos Solano Atehortúa ◽  
Sandra Patricia Isaza Jaramillo ◽  
Ana Rendón Bañol ◽  
Omar Buritica Henao

Background: There are few published epidemiological studies concerning dystonia. Its true prevalence has been difficult to establish. There is no data published in Latin America on this matter. Methods: In this study the prevalence of dystonias in the Department of Antioquia (Colombia) was estimated using a capture-recapture methodology with log-linear modeling, including cases in 3 centers for neurological referrals that cover the Department of Antioquia from 2007 to 2012. Results: The overall prevalence was 712 per 1,000,000 (95% CI 487-937). Of the total of 874 patients, 79% had primary dystonias, and 75.5% had focal dystonias. The delay in diagnosis was longer for primary dystonias, with a median of 1 year. Conclusion: We found a high prevalence of dystonias in Antioquia. The frequency of the different types of dystonias, as well as the demographic characteristics of our patients, is similar to data from other populations of the world.


2007 ◽  
Vol 136 (1) ◽  
pp. 14-22 ◽  
Author(s):  
N. A. H. VAN HEST ◽  
A. D. GRANT ◽  
F. SMIT ◽  
A. STORY ◽  
J. H. RICHARDUS

SUMMARYCapture–recapture analysis has been used to evaluate infectious disease surveillance. Violation of the underlying assumptions can jeopardize the validity of the capture–recapture estimates and a tool is needed for cross-validation. We re-examined 19 datasets of log-linear model capture–recapture studies on infectious disease incidence using three truncated models for incomplete count data as alternative population estimators. The truncated models yield comparable estimates to independent log-linear capture–recapture models and to parsimonious log-linear models when the number of patients is limited, or the ratio between patients registered once and twice is between 0·5 and 1·5. Compared to saturated log-linear models the truncated models produce considerably lower and often more plausible estimates. We conclude that for estimating infectious disease incidence independent and parsimonious three-source log-linear capture–recapture models are preferable but truncated models can be used as a heuristic tool to identify possible failure in log-linear models, especially when saturated log-linear models are selected.


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