A stage-based population model for American alligators in northern latitudes

Abstract

Very little is known about the population dynamics of American alligators in northern latitudes. To better define the characteristics of the northern population, we combined published life-history and vital rate data for studies conducted in North Carolina and South Carolina; for comparison, we gleaned the same information from the literature for the southern (Florida and Louisiana) population. We constructed a 5-stage Lefkovitch matrix model for each population. The models showed that the southern population was stable and slightly increasing (λ = 1.02), whereas the northern population was in decline (λ = 0.870). We integrated potential impacts of climate change into the northern population model to determine how the population might respond to increased temperature and decreased precipitation. An increase in temperature would benefit the northern population; however, a decrease in precipitation or the combined effects of temperature increase and precipitation decrease would negatively affect the viability of the northern population. Two priorities result from modeling these scenarios: 1) a long-term monitoring program is needed to acquire the life-history and vital rate data on the northern population, and 2) current alligator habitat must be conserved or improved to insulate the species from potential drought associated with climate change. © 2014 The Wildlife Society.