Journal Article

Modeling misidentification errors in capture–recapture studies using photographic identification of evolving marks

Pollock, Kenneth H., Brownie, Cavell, Webster, Raymond A., Yoshizaki, Jun

2009

Overview

Misidentification of animals is potentially important when naturally existing features (natural tags) are used to identify individual animals in a capture–recapture study. Photographic identification (photoID) typically uses photographic images of animals' naturally existing features as tags (photographic tags) and is subject to two main causes of identification errors: those related to quality of photographs (non‐evolving natural tags) and those related to changes in natural marks (evolving natural tags). The conventional methods for analysis of capture–recapture data do not account for identification errors, and to do so requires a detailed understanding of the misidentification mechanism. Focusing on the situation where errors are due to evolving natural tags, we propose a misidentification mechanism and outline a framework for modeling the effect of misidentification in closed population studies. We introduce methods for estimating population size based on this model. Using a simulation study, we show that conventional estimators can seriously overestimate population size when errors due to misidentification are ignored, and that, in comparison, our new estimators have better properties except in cases with low capture probabilities (<0.2) or low misidentification rates (<2.5%).

• Publisher: Ecological Society of America
• Subject: Animal and plant ecology / Animal Identification Systems / Animal populations / Animal, plant and microbial ecology / Animals / Biological and medical sciences / capture–recapture / closed-population models / Computer Simulation / Ecological modeling / Ecology / Errors / Estimating techniques / Estimation bias / Estimation methods / Estimators / evolving tags / Fundamental and applied biological sciences. Psychology / General aspects / General aspects. Techniques / Methods and techniques (sampling, tagging, trapping, modelling...) / misidentification / Modeling / Models, Biological / natural tags / photographic identification / Photography / Photography - methods / Population Density / Population estimates / Population number / Population size / population size estimate / Population studies / Research Design / Salamanders / Simulation / Time Factors