Efficiency of a new reverse-bait trigger snap trap for invasive rats and a new standardised abundance index

International audienceWe compared trapping and kill efficiency, and by-catch rate of a new reverse-bait trigger rat trap (Ka Mate) with conventional snap traps (Ezeset and Victor), and assessed methods for calculating abundance indices, over 2879 trap nights on Wallis & Futuna and New Caledonia. Ka Mate traps were most effective at killing larger (> 100 g) rats whereas Ezeset traps had the best capture rates of smaller (< 100 g) rodents. Victor mouse traps caught rodents up to 50 g, but were no more efficient than rat traps. Proportions of live captures were similar for Ka Mate and Ezeset traps, but the mass threshold for live rats in Ezeset traps was much lower than that of the Ka Mate traps. Ka Mate traps had much lower non-target by-catch rates than Ezeset traps in habitats free of land crabs. We developed a new rodent abundance index to standardise results of different trap systems