Telemetry-Based Assessment of Home Range to Estimate the Abundance of Invasive Green Monkeys on St. Kitts

Green monkeys (Chlorocebus sabaeus) have been a "pest" species on the Caribbean island of St. Kitts for hundreds of years, and data on their abundance are crucial to inform effective management strategies. To estimate population size, we present the first use of radio telemetry tracking technology combined with home range estimation and habitat analysis. We use detailed tracking information collected from 10 monkeys from nine different troops in four different biotic areas. For each tracked animal, bootstrapped Brownian bridge home range estimates were calculated from GPS positional data (90% with replacement) to quantify space use by troops. The home range area estimates for the different biotic areas were used to estimate the total troop number across the whole island based on land use cover. We modelled an estimate of population size accounting for variation in space use by troops, variation in troop number by biotic area, and uncertainty around number of individuals in a troop. Our results, which we will continue to refine with additional data, show that the 174 km(2) island is home to between 690 and 929 monkey troops, or between 22,000 and 37,000 green monkeys.