Spatial Ecology of Invasive Predatory Species Informs Predator Control Program for the Jamaican Rock Iguana (Cyclura collei)

Abstract

Abstract Extinctions and population decline of species on islands are often attributed to invasive alien species (IAS). Predation from IAS, such as the Small Indian Mongoose (Urva auropunctata) drove the Critically Endangered Jamaican Rock Iguana (Cyclura collei) to near extinction. Historical and ongoing conservation efforts have restored the population to 500 to 600 adults today. Despite intensive control, IAS incursions into the core area remain common, preventing natural population recruitment. To improve our management and understanding of IAS, we investigated IAS spatial use within the range of the Jamaican Rock Iguana. Seventeen mongooses and cats were tracked with Very High Frequency (VHF) and Global Positioning System (GPS) transmitters for up to 72 days. Several spatial analyses were performed for all IAS, and home ranges were calculated for 13 individuals. Average 100% Minimum Convex Polygon (MCP) home range for VHF tracked mongoose and cats were 25.7 ha and 23.9 ha, respectively. Average 100% MCP, 95% Kernel Density Estimate (KDE), and 50% KDE home range estimates for GPS tracked cats were 78.2 ha, 80.3 ha, and 21.6 ha, respectively. Average IAS range length (distance between the two farthest points) was 979.2 m. Tracking tunnels were also utilized and revealed nearly equal numbers of mongoose tracks inside and outside the iguana core zone. Our results suggest the use of 100 m grid spacing for traps and the introduction of a buffer zone surrounding the core protected zone to restrict IAS incursions. The suggested modifications are expected to mitigate the effects of IAS on the Jamaican Rock Iguana population, improve hatchling survival, and facilitating natural population recruitment and growth.