The Robust Design RD was originally developed specifically for the problem of "robust estimation" of abundance and recruitment in open CMR studies, to deal with the fundamental problem encountered with the ordinary JS /CJS study design and data:
Recaptures over the "open" time intervals (where mortality or recruitment can occur) precludes the use of closed abundance models that allow for robust modeling of heterogeneity in capture/recapture probabilities.
"Open" JS, POPAN and Pradel models require simple assumptions about capture (no behavior or individual heterogeneity effects), the violation of which can seriously bias estimates of abundance and recruitment.
However, the RD has been extended to many more general applications, some of which we will consider here. These generically revolve around situations in which marked animals can temporarily leave a study area, and thus are unavailable to capture.Â
Currently, users (at least those that are operating within the MARK/RMark framework) must decide whether the focus is more on recruitment/ immigration, or on temporary emigration. This will in turn guide the specific models that are appropriate, the basic data design being the same (and survival and abundance estimates available under either):
Pradel or POPAN models that use unconditional (first captures part of the likelihood) open encounter histories and provide inference on recruitment/immigration.
Standard Robust models that use conditional (CJS) and provide inference on temporary emigration.
Next: Recruitment models