Monitoring a problem: evaluating the ecological status of the invasive Nile Monitor in Florida and forecasting population expansion using computational GIS

Guy Harvey Oceanographic Center Facility

The state of Florida is an epicenter for the introduction of exotic terrestrial and marine species, often which are attributed to the pet industry. Identifying the threats posed by exotics that may become invasive is critical to manage and protect indigenous species and habitats. One such exotic that is now invasive in Florida is the Nile Monitor (Varanus niloticus). The Nile monitor is a large, predatory lizard native to central and southern Africa that is thought to have been introduced to Florida via both intentional and unintentional releases associated with the exotic pet trade. Since their introduction, Nile monitors have infiltrated much of central and southern Florida despite ongoing eradication efforts. The broad ecological plasticity and generalist diet of the Nile monitor affords them the potential to establish novel environments and to disrupt the trophic stability of a wide range of habitats. Unfortunately, there has been inadequate study of the metapopulation dynamics of the lizard in Florida as well as absent detailed analyses in the literature of their potential expansion and the ecological cost of their establishment. In this study, verified, georeferenced observations and specimen capture records of the monitor in Florida will be analyzed to quantify their present distribution and spatio-temporal dynamics of the invasive population. Through multivariate analysis of bioclimatic data for localities where the lizards have been recorded, information will be assembled conferring the physiological preferences and distribution correlations of the Nile monitor in their invasive range. Capture and observation records for the monitor will be linked to a habitat classification map, developed through GIS analysis of land cover, to identify ecotype preferences of the invasive population. Knowledge of habitats presently utilized by Nile monitors in Florida, in combination with bioclimatic factors and projections on future climatic conditions, can inform corridors of population spread and assess habitats at greater risk for invasion. Identifying areas at risk for Nile monitor incursion and corridors of spread will allow resource managers to act swiftly and precisely to prevent negative impacts to native fauna and also help prevent the establishment of additional breeding populations.