A Literature Review for Monitoring Rare and Elusive Species, and Recommendations on Survey Design for Monitoring Boreal Caribou

Effective wildlife management requires monitoring changes in the spatial distribution of species, their population size and their population trend (Williams et al. 2002; Sinclair et al. 2006). Reliable estimates of these population characteristics are necessary for determining current population status and providing a basis for evaluating management decisions in an adaptive management framework (Holling 1978). Obtaining reliable estimates of population distribution, size or trend, however, is not a trivial task. Surveys designed to collect the relevant data are often costly and challenged by environmental factors (e.g., weather, land cover) and animal behaviours that can cause imperfect detection of all individuals, leading to estimates that are biased and/or imprecise (Williams et al. 2002). Obtaining reliable estimates is particularly challenging for rare and elusive species. Low densities typically confound standard monitoring methods causing low encounter rates and the resulting estimates are usually too imprecise to effectively inform management (Thompson 2004). Yet, rare or elusive species are frequently a primary concern for management because many such species are often designated as threatened or endangered and/or deemed to be data-deficient (Drever et al. 2012). Because of their conservation concern, significant research effort continues to be directed at developing reliable, cost effective monitoring methods for rare and elusive species (Thompson 2004; Conroy et al. 2008; Johnson et al. 2013; Royle et al. 2013). Here, we review recent advances in methods for monitoring rare and elusive species. We begin with an overview of common sampling designs and methods for collecting relevant data. We then examine statistical methods for estimating the population characteristics of spatial distribution, size and trend.