Evaluating the Ecological Status of the Introduced Nile Monitor (Varanus niloticus) in Florida: Forecasting Presence and Population Expansion Using Computational Geographic Information Systems

• Main Author: Cohen, Noah G
• Format: Others
• Published: NSUWorks 2017
• Subjects: climate; Florida; GIS; habitat; invasive species; species distribution modelling; Varanidae; Marine Biology; Oceanography and Atmospheric Sciences and Meteorology; Population Biology; Zoology
• Online Access: https://nsuworks.nova.edu/occ_stuetd/477; https://nsuworks.nova.edu/cgi/viewcontent.cgi?article=1479&context=occ_stuetd

The Nile monitor (Varanus niloticus) is a large, carnivorous lizard that has become a notorious invasive species in Florida, USA. Initially released in the 1980s from the pet trade, the species has since established at least three breeding populations and spread throughout much of southern Florida. While current control efforts have failed to eradicate V. niloticus, it is important to attain a better understanding of its invasive dynamics to guide and inform better control strategies. In this study, available georeferenced records of V. niloticus in Florida were compiled and linked to a habitat classification map to evaluate ecotype preferences. Factored with bioclimatic data, the regional spread of V. niloticus was modelled for contemporary and projected (i.e., in the year 2050) presence using Maxent and Mahalanobis Distance models. Study results indicate that V. niloticus maintains a strong presence in eastern Lee County on the southwestern coast. Populations in Palm Beach and Miami-Dade counties on the southeastern coast may be interconnected, contrary to current descriptions that they are separated from each another. Model forecasts of conditions for the year 2050 identify widespread expansion of V. niloticus in Florida, particularly northward with the establishment of a new population center in Pasco County in the western central peninsula. This is the first known modelling study of V. niloticus in Florida and identifies regions at greater risk for future population expansion.