A foundation for the distance sampling methodology

The population size ("abundance") of wildlife species has central interest in ecological research and management. Distance sampling is a dominant approach to the estimation of wildlife abundance for many vertebrate animal species. One perceived advantage of distance sampling over the well-known alternative approach of capture-recapture is that distance sampling is thought to be robust to unmodelled heterogeneity in animal detection probability, via a conjecture known as "pooling robustness". Although distance sampling has been successfully applied and developed for decades, its statistical foundation is not complete: there are published proofs and arguments highlighting deficiency of the methodology. This work provides a design-based statistical foundation for distance sampling that has attainable assumptions. In addition, because identification and consistency of the developed distance sampling abundance estimator is unaffected by detection heterogeneity, the pooling robustness conjecture is resolved.