Estimation of Biases in Mark-Recapture Census with a Modified Jackson's Method when the Population Density is Changing

Abstract

Method to estimate population parameters based on single release-multi-recapture census were developed for cases where the population density changed during the study period, based on Hamada's (1976) methods which could be applicable only to stable populations. Simulation study showed that: (1) The change in population density (V) did not affect the bias of estimated density but affected that of estimated survival rate. (2) The number of unmarked individuals Û0 estimated with the z-method always gave underestimation at a constant rate of (1—R), when the rate of capture (R) was constant but the intensity of underestimation of the density estimate (Û0) with the z'-method was less than that with the z-method. (3) Bias of Û'0 was negligible when the survival rate S was near unity but increased with the decrease of S. It eventually approached (1—R). The similar trend was also seen in the relation between bias of [Formula Omitted]when the population density changed with a constant rate V; (4) The z'-method gave a better estimate than the z-method when the rate of capture changed. A method to obtain less-biased estimate of U0 from Û'0 was presented. © 1980, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.