Estimating Abundance from Capture Recapture Data

Capture-recapture models are a foundational tool in population ecology, because we recognize that the individuals we observe at any point in time represent only a sample from some larger population of interest. Conceptually, estimating population abundance requires us to model and estimate detection probability, the proportion of individuals in the population that occur in a sample. In this chapter, we consider the use of capture-recapture models for estimating abundance, and explore how insights into sampling and ecological processes allow us to model detection across time, space, and individuals, thus improving abundance estimates. We review standard capture-recapture models for estimation of abundance, including their assumptions and applications. We include in our review models where populations are assumed demographically and geographically closed during sampling, and models that relax that assumption. We also review recent advances arising from the development of hierarchical capture-recapture models and spatial capture-recapture (SCR) models.