Population estimation in African elephants with hierarchical Bayesian spatial capture-recapture models
No Thumbnail Available
Date
2017
Authors
Marshal, Jason Paul
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
With an increase in opportunistically-collected data, statistical methods that can accommodate unstructured designs are increasingly useful. Spatial capturerecapture (SCR) has such potential, but its applicability for species that are strongly gregarious is uncertain. It assumes that average animal locations are spatially random and independent, which is violated for gregarious species. I used a data set for African elephants (Loxodonta africana) and data simulation to assess bias and precision of SCR population density estimates given violations in location independence. I found that estimates were negatively biased and likely too precise if non-independence was ignored. Encounter heterogeneity models produced more realistic precision but density estimates were positively biased. Lowest bias was achieved by estimating density of groups, group size, and then multiplying to estimate overall population density. Such findings have important implications for the reliability of population density estimates where data are collected by unstructured means.
Description
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2017.
Keywords
Citation
Marshal, Jason Paul (2017) Population estimation in Africa elephants with hierarchical Bayesian spatial capture-recapture models, University of the Witwatersrand, Johannesburg, <http://hdl.handle.net/10539/23535>