Proceedings of the Vertebrate Pest Conference

Due to its unique biodiversity and extreme endemism rates, New Caledonia archipelago is listed as one of Earth’s 35 biodiversity hotspots. New Caledonian biota is now threatened by invasive species, with introduced rats considered to be particularly damaging. At the initiative of local institutions and NGOs, an innovative scientific experiment has been launched to quantify the Response of Forest Ecosystems to Rodent and Cat Control (REFCOR) and to test the relevance of such control at a large spatial scale (200 ha) on a dense evergreen rainforest (Mont Panié Wilderness Nature Reserve). Rat control will begin mid-2014 with a short toxin knockdown, and will thereafter involve intensive trapping sessions over the next 6 years, together with biodiversity monitoring and experiments. Rat impact studies initiated in early 2013 also aim to identify possible biodiversity indicators that could be used for a rapid assessment of rat control efficiency and effects. One of the major impacts of invasive rats is the disruption caused to plant and bird reproduction processes, placing them at high risk. Pre-and post-control experiments include the assessment of palm fruit consumption rates and of predation risk to artificial bird nests. Initial surveys of both rat populations and palm fruits (2 species), as well as artificial bird nest predation experiments, were conducted in 2013. Rat abundance was high, fluctuating among study areas and seasons, with more individual reproducers in December than in May. Fruit predation was high for one of the two species, in line with the rat abundance pattern. Surprisingly, artificial bird nest predation by rats was far lower than expected. These first results corroborate the influence of rats on some taxa. Monitoring and experiments will be repeated after and throughout rat control. This “before-after-control-impact” project, conducted in close collaboration with local stakeholders (Dayu Biik NGO), offers a unique opportunity to evaluate 1) the feasibility of controlling rat populations in the New Caledonian rainforest by trapping as an alternative to long-term poisoning, and 2) the benefits of rat control for native biodiversity and rainforest ecosystem functioning.