Anoplolepis populations have also proven devastating to native land crabs, including the
red land crab Gecarcoidea natalis, of which up to 20 million have died due to the
formidable formic acid it possessed by the ant (O’Dowd et al. 1999; Parks Australia
2005). Regulators of the natural island rainforest ecosystem, land crabs maintain high
nutrient cycling rates in the forest ecosystem by degrading leaf litter, reducing new
seedling recruitment and speeding up the microbial decomposition processes (CBD
2003; Parks Australia 2005). The loss of the crab, as well as other changes incited by
the high densities of the ant, are presenting serious problems to native habitats and
endemic species on the island, as well as indirectly threatening tourism and the
aesthetic value of the island for the public.
As well as significantly and quickly altering the natural ecosystem processes and the
associated environment, the yellow crazy ant has reduced native bird, reptile and
mammal life. The excellent competitive ability of the ant is thought to be due to the
ant’s high foraging intensity and its greater foraging ability (for example it is able to
utilise food sources in difficult-to-reach locations such as the rain forest canopy)
(O’Dowd et al. 1999).