Unmarked: An R package for fitting hierarchical models of wildlife occurrence and abundance

Ecological research uses data collection techniques that are prone to substantial and unique types of measurement error to address scientic questions about species abundance and distribution. these data collection schemes include a number of survey methods in which unmarked individuals are counted,or determined to be present,at spatially- referenced sites. examples include site occupancy sampling,repeated counts,distance sampling,removal sampling,and double observer sampling. to appropriately analyze these data,hierarchical models have been developed to separately model explanatory variables of both a latent abundance or occurrence process and a conditional detection process. because these models have a straightforward interpretation paralleling mecha- nisms under which the data arose,they have recently gained immense popularity. the common hierarchical structure of these models is well-suited for a unied modeling in- terface. the r package unmarked provides such a unied modeling framework,including tools for data exploration,model tting,model criticism,post-hoc analysis,and model comparison.