Exploring the potential population impacts of puma predation on a mainland Magellanic penguin colony through an interactive tool

The success of restoration efforts has resulted in the expanding range of large predators from their historical lows in many areas of the world. In many cases these predators are returning to ecosystems that have been altered since their historical presence, resulting in novel interactions and presenting managers with complex conservation issues. Quantitative tools that allow managers to interactively build scenarios and evaluate potential outcomes in an intuitive manner may improve understanding and decision making. To demonstrate the utility of such tools in a complex, novel system, we built an interactive R Shiny application to model the population dynamics of a mainland Magellanic penguin colony and the effects of predation by a recovering puma population in Monte León National Park, Argentina. To facilitate scenario building and exploration by readers and managers alike, we include the code to run the R Shiny application in the Supplementary Information. Under the default values of the demographic and predation rates that we set to reflect our best understanding of current conditions, the penguin colony is projected to continue increasing into the future until a density-dependent upper stability with minimal risks of extinction. However, sensitivity analysis reveals that the population is highly susceptible to the interaction between autocorrelated environmental stochasticity and additive mortality from puma predation. Increases in environmental variance (simulating extreme climate events, or swings in fisheries stocks) combined with puma predation result in significantly higher probabilities of extinction in the coming decades. Our tool has the flexibility to model a wide range of scenarios for Magellanic penguin colonies or other populations facing additive mortality from predation, explorations that are easily implementable due to the tool's open-source code.