An invasion of the yellow crazy ant poses continued risk for the booby population. Yellow crazy ants formed supercolonies in the 1990s and spread throughout 28% of the islands forest. Starting in 2000, efforts to control it eliminated it from 2,800 ha of forest, resulting in a 95% reduction of its range. The range was 300 ha in 2005, at much lower densities than originally, although it has slightly recovered since then. The ants could prey on nestlings and cause nest abandonment, although this has not been observed. They do, however, disrupt the ecosystem by killing red crabs, and farm scale insects that damage the trees where the boobies nest.