Vortex is a flexible, individual-based stochastic simulation tool for conducting population viability analyses on a wide range of species. The software models population dynamics as discrete, sequential events that occur according to probabilities that are random variables following user-specified distributions. Vortex simulates a population by stepping through a series of events that describe an annual cycle of a typical sexually reproducing, diploid organism: mate selection, reproduction, mortality, incrementing age by one year (or timestep – see below), migration among populations, removals, supplementation, and then truncation (if necessary) to the carrying capacity. The simulation of the population is iterated many times to generate the distribution of fates that the population might experience. The Vortex software is maintained by the Species Conservation Toolkit Initiative (SCTI).

Download the most recent versions of theVortex software and manual from the SCTI website.

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