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Rodents remain one of the most widespread and damaging invasive alien species on islands globally. The current toolbox for insular rodent eradications is reliant on the application of sufficient anticoagulant toxicant into every potential rodent territory across an island. Despite significant advances in the use of these toxicants over recent decades, numerous situations remain where eradication is challenging or not yet feasible. These include islands with significant human populations, unreceptive stakeholder communities, co-occurrence of livestock and domestic animals, or vulnerability of native species. Developments in diverse branches of science, particularly the medical, pharmaceutical, invertebrate pest control, social science, technology and defense fields offer potential insights into the next generation of tools to eradicate rodents from islands. Horizon scanning is a structured process whereby current problems are assessed against potential future solutions. We undertook such an exercise to identify the most promising technologies, techniques and approaches that might be applied to rodent eradications from islands. We highlight a Rattus-specific toxicant, RNA interference as species-specific toxicants, rodenticide research, crab deterrent in baits, prophylactic treatment for protection of non-target species, transgenic rodents, virus vectored immunocontraception, drones, self-resetting traps and toxicant applicators, detection probability models and improved stakeholder community engagement methods. We present a brief description of each method, and discuss its application to rodent eradication on islands, knowledge gaps, challenges, whether it is incremental or transformative in nature and provide a potential timeline for availability. We outline how a combination of new tools may render previously intractable rodent eradication problems feasible.

Rodent eradications undertaken on tropical islands are more likely to fail than eradications undertaken at higher latitudes. We report on 12 independent rodent eradication projects undertaken on tropical islands that utilized the results of an in situ bait availability study prior to eradication to inform, a priori, the bait application rate selected for the eradication. These projects also monitored bait availability during the eradication. The results from our analysis verified the utility of bait availability studies to future rodent eradication campaigns and confirmed the influence of two environmental factors that can affect bait availability over time: precipitation prior to the study and the abundance of land crabs at the study site. Our findings should encourage eradication teams to conduct in-depth assessments of the targeted island prior to project implementation. However, we acknowledge the limitations of such studies (two of the projects we reviewed failed and one removed only one of two rodent species present) and provide guidance on how to interpret the results from a bait availability study in planning an eradication. Study design was inconsistent among the twelve cases we reviewed which limited our analysis. We recommend a more standardized approach for measuring bait availability prior to eradication to provide more robust predictions of the rate at which bait availability will decrease during the eradication and to facilitate future comparisons among projects and islands.

Dugong dugon are the last extant species in the Family Dugongidae and are listed as Vulnerable to extinction by the IUCN Red List. The dugong population is believed to be in decline globally. Throughout its range, relic populations remain and are separated by large areas where populations have disappeared (Marsh & Lefebvre 1994). The degree of the decline of numbers or fragmentation of its range is not known for any country. For many countries the only information available is from incidental sightings, drownings and anecdotal information. The Pacific region supports the world's largest remaining population of dugongs (Marsh et al. 2002). Dugong occur in most of Melanesia, Papua New Guinea (PNG), the northeast and east coasts of Australia and as far east as Vanuatu.. The current status of dugongs is unknown throughout the region (Marsh et al. 2002) and information on dugong distribution and abundance is outdated or non-existent. It is likely that dugongs are widely distributed in small numbers in much of PNG. the Solomon Islands and Vanuatu and that larger numbers occur in the Papua New Guinea waters of Torres Strait. Marsh et al. (2002) states that their reliance on relatively shallow water seagrass beds for food, limits the ability of dugongs to travel between islands and continents that are separated by extensive areas of deep water. For this reason, many island populations become essentially isolated, making these populations especially vulnerable to extinction.