ABSTRACT
Occupancy models are a set of techniques for investigating the presenceabsence of a species while accounting for the fact that the species may be present but goes undetected by the survey methods used at some locations. Such methods can be useful in a wide range of ecological applications, such as species distribution modeling, metapopulation studies, habitat modeling, and resource selection functions, and can also be useful for monitoring programs (MacKenzie et al., 2006). They are useful not only for assessing patterns in species occurrence, such as identifying important habitat relationships to the current distribution, but also for understanding and predicting changes in species distributions through time. Occupancy models have also been extended beyond presence-absence data (or, more generally, two categories for the status of the species at a unit) to multiple categories (e.g., absence and presence with or without breeding; or none/some/many individuals) (Royle and Link, 2005; Nichols et al., 2007; MacKenzie et al., 2009).
