Search the SPREP Catalogue

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.

The inextricable links between climate change and sustainable development have been increasingly recognised over the past decade. In 2007, the Intergovernmental Panel on Climate Change (IPCC)1 concluded with very high confidence that climate change would impede the ability of many nations to achieve sustainable development by mid-century and become a security risk that would steadily intensify, particularly under greater warming scenarios. Article 4.8 of the United Nations Framework Convention on Climate Change (UNFCCC) lists several groups of countries that merit particular consideration for assistance to adapt to climate change “especially: (a) small island countries, (b) countries with low-lying coastal areas, c) countries with areas prone to natural disasters.” Small Island Developing States (SIDS) have characteristics which make them particularly vulnerable to the effects of climate change, sea level rise (SLR) and extreme events, including: relative isolation, small land masses, concentrations of population and infrastructure in coastal areas, limited economic base and dependency on natural resources, combined with limited financial, technical and institutional capacity for adaptation.2

The nations of CARICOM16 in the Caribbean together with Pacific island countries contribute less than 1% to global greenhouse gas (GHG) emissions (approx. 0.33%17 and 0.03%18 respectively), yet these countries are expected to be among the earliest and most impacted by climate change in the coming decades and are least able to adapt to climate change impacts. These nations’ relative isolation, small land masses, their concentrations of population and infrastructure in coastal areas, limited economic base and dependency on natural resources, combined with limited financial, technical and institutional capacity all exacerbates their vulnerability to extreme events and climate change impacts. Stabilising global GHG emissions and obtaining greater support for adaptation strategies are fundamental priorities for the Caribbean Basin and Pacific island countries. CARICOM leaders recently unveiled their collective position that global warming should be held to no more than 1.5°C19 and continue to develop a Climate Change Strategic Plan. The Pacific island countries have expressed their priorities for addressing climate change regionally through the Pacific Leaders’ Call to Action on Climate Change20 and the Pacific Islands Framework for Action on Climate Change 2006-2015.21