The continuing march of Common Green Iguanas: arrival on mainland Asia

The popularity of the Common Green Iguana (Iguana iguana) as a pet has contributed to its global occurrence as an invasive alien species. Early detection and control of alien I. iguana populations is necessary to prevent the need for large and financially demanding eradication actions. Here, we first collated information from digital footage and interviews regarding sightings of free roaming I. iguana specimens in Singapore and Thailand. We use this information to report and discuss an ongoing invasion with early stage establishment being facilitated by release of pets and escape from recreational parks, as well as the resulting conservation implications. Using species-distribution modeling to assess the potential distribution in Southeast Asia, we identify large regions with suitable habitat that could aid the expansion of these alien populations in the absence of future control measures. In addition, given the availability of suitable habitat throughout the Philippine archipelago and its high number of imported iguanas and within-country trade, we call for awareness of future alien I. iguana populations in the Philippines. Next, the alien population in Singapore is of additional concern given that the excellent swimming capacity of I. iguana allows it to reach neighboring Sumatra and > 3,000 islands of the Indonesian Riau archipelago. Finally, we report I. iguana sightings in Hong Kong and Peninsular Malaysia. We provide strategy recommendations for implementing mitigation efforts and to halt future release and spread in order to prevent negative biodiversity impacts associated with a large invasive alien I. iguana population.