Yellow Crazy Ant - Measures

Measures

To reduce the impacts of crazy ants on red crabs and the island's ecosystems the national park carried out a major aerial baiting program in 2009, to follow up the first aerial baiting conducted in 2002. The first step was conducting an extensive island-wide survey to work out exactly where the supercolonies were. For several months staff traversed the entire island surveying over 900 sites. The result was a map of crazy ant supercolonies and red crab burrow densities together with other biodiversity data. In September 2009, a helicopter was used to precisely bait crazy ant supercolonies, which covered 784 hectares of the island. A very low concentration of Fipronil bait (a tenth of 1 per cent) was used to control the ants. Monthly monitoring of these baited supercolony sites shows that crazy ant densities were reduced by 99 per cent. Park staff placed a high emphasis on minimising any non-target impacts of baiting. Food lures were dropped from a helicopter to attract robber crabs away from areas that were about to be baited. This technique, combined with the low concentration Fipronil bait, proved to be highly successful with extremely low numbers of robber crabs and no red crabs known to be killed by the baiting.