A review of the generic computer programs ALEX, RAMAS/space and VORTEX for modelling the viability of wildlife metapopulations

An assessment is presented of three computer packages, ALEX, RAMAS/space and VORTEX, that have been developed for analyses of metapopulation viability. Their usefulness was assessed in the context of the need to understand the assumptions and limitations of the programs. The study examined many attributes of these programs, ranging from availability and "user-friendliness" to the mathematical structure and procedures underpinning the sub-models. Key features and strengths of, and differences between, the various programs were highlighted. They are structured differently and vary in the way processes such as environmental and demographic variation are modelled. Many of these differences reflect what the architects of the programs consider to be the most important factors influencing the viability of metapopulations. These differences mean that the programs may produce different results even for investigations of the same populations. The selection of the most appropriate program should be based on a range of key criteria including: (1) the key question(s) and objectives of the study, and, (2) the strengths, limitations and assumptions that underpin the program and how these match the attributes, life history parameters and available data for the target species. The processes of data assembly, running the programs and reading the accompanying documentation give the user an improved understanding of population behaviour and dynamics. The wide variety of threatened taxa and diversity of conservation problems highlight the value of a broad range of sound, well-developed and relatively error-free packages for simulating metapopulation viability. However, in some cases it may be more appropriate to develop a new program that is tailored specifically to the requirements of a particular management problem.