Bootstrap interval estimation of wildlife population sizes from multiple surveys

The research deals with bootstrap interval estimation of wildlife population sizes frommultiple surveys in the Hluhluwe-Umfolosi Park. The jackknife procedure was also usedto provide the standard errors for the survey estimates. The main wildlife speciese studiedin the research were the White and Black Rhino. The survey estimates for the wildlifespecies were obtained using line transect sampling and mark-recapture methodsrespectively. The bootstrap and jackknife procedures were applied separately to each ofthe datasets. Bootstrap estimates for each of the time point were obtained and theconfidence intervals of the bootstrap estimates were constructed using percentile andstandard methods. The coverage probability was assessed using the Monte Carlosimulations. Only the nonparametric bootstrap was applied in this research and the resultswere compared to the jackknife results. The lengths of the confidence intervals were usedto assess the confidence intervals with a shorter confidence interval being more exact.The estimates used for both the bootstrap and jackknife methodology were based on asimple state space model. The discrete state space model used was proposed by Fatti et al(2002). State space models provide a natural framework for estimating and predictinganimal population abundance given partial or inexact information. The model takes intoaccount the (unknown) birth rate in the population and all known losses (mortalities andrelocations) and gains (introductions) in the population between successive surveys aswell as the errors in the survey estimates.