Invasive reptiles and amphibians: global perspectives and local solutions

Abstract

In the annals of invasive species biology, higher taxa such as mammals, plants and insects have received the lion’s share of research attention, largely because many of these invaders have demonstrated a remarkable ability to degrade ecosystems and cause economic harm. Interest in invasive reptiles and amphibians (collectively ‘herpetofauna’, colloquially ‘herps’) has historically lagged but is now garnering increased scrutiny as a result of their escalating pace of invasion. A few herpetofaunal invaders have received considerable attention in scientific and popular accounts, including the brown treesnake Boiga irregularis on Guam, Burmese python Python molurus in Florida, Coqui Eleutherodactylus coqui in Hawaii and cane toad Bufo marinus in Australia. However, relatively few are aware of many emerging and potentially injurious herpetofaunal invaders, such as Nile monitors Varanus niloticus in Florida, common kingsnakes Lampropeltis getula in the Canary Islands, boa constrictors Boa constrictor on Aruba and Cozumel, or a variety of giant constrictor snakes in Puerto Rico. For the vast majority of the most commonly introduced species, real or potential impacts to native ecosystems or human economic interests are poorly understood and incompletely explored; major pathways of introduction have only recently been elucidated, and effective management interventions have been limited (Kraus, 2009). The goal of this symposium was to bring together an international community of biologists working on invasive reptiles and amphibians so as to facilitate better communication of findings and sharing of ideas among this relatively small and geographically dispersed group of researchers. To date, those studying invasive herpetofauna have often been unaware of relevant research and control efforts in other countries and have lacked a working network for sharing data, ideas and potential control tools. The international trade in live reptiles and amphibians, valued in the billions of dollars, virtually ensures that establishment of alien herps will continue until the scale of the problem is more widely known and intervention is organized across multiple countries. The symposium consisted of 20 oral presentations over 2 days, with a total of 27 authors from countries including Australia, Canada, Japan, Portugal, South Africa, UK and USA. Among the many outstanding presentations were examination of links between invasive amphibians and the spread of Batrachochytrium, economic analysis of early detection and rapid response, education and outreach initiatives, an exploration of means of reducing intentional or accidental release of herps from the pet trade and case studies of control of bullfrogs, clawed frogs and viperine snakes. Evening discussions and subsequent email correspondence have enabled many of the participants to keep abreast of ongoing research findings and regulatory approaches that have been proposed or implemented to mitigate the effects of invasive herpetofauna. The three symposium contributions featured in this section (Kikillus, Hare & Hartley, 2010; Shanmuganathan et al., 2010; van Wilgen et al., 2010) address different topics directly relevant to improving management of invasive herpetofauna. We feel it is timely to emphasize this particular aspect of invasive-species biology because it is often neglected by the academic community, which more often treats biological invasions as a strictly (or primarily) biological phenomena. But they are not. The recent explosion of biological invasions, including the exponential growth in herpetofaunal introductions (Kraus, 2009) is primarily driven by cultural or social imperatives, not biological ones. Hence, solutions to the widespread transport and release of these organisms must also be cultural, social and political. For those social, cultural and political solutions to be attempted requires more detailed knowledge of what solutions might look like – we need improved knowledge of how and why species are transported, which species will establish and prove invasive and which methods might be used to mitigate the worst impacts of invaders. The symposium presentations featured here address factors driving the importation of live reptiles, develop models predicting invasion success and assess the potential utility of biocontrol against a notorious invader. Thus, they move us toward developing the knowledge required to mitigate and stop this global conservation problem.