Chapter 13 - Population Estimation with Radio-Marked Animals

Abstract

This chapter discusses three uses of radio-marked animals to estimate population size. Direct mark–resight estimation of a given number of individuals (N) is considered first, where the probability of observing an individual in the population is estimated from observation rates of radio-marked individuals that are present in the population. Second, the chapter discusses the use of sight ability models developed from radio-marked animals, where trials are conducted to estimate the probability of sighting given that the radio-marked animal is present on a survey unit. Covariates, such as size of the group of animals containing the radio-marked individual at the time of the survey or the percent vegetation cover of the animal's location during the survey, are used to develop models that predict the probability of sighting individuals in the population. Finally, the chapter considers how radio-marked animals can resolve the issue of estimating animal density from a trapping grid of size A with N individuals estimated from mark–recapture methods. By radio-marking a sample of individuals captured on the grid and tracking them shortly after the grid trapping procedure is finished, the proportion of their locations that occurs on the former trapping grid can be used to correct the bias of the naive estimate of density.