Document ID: chunk:federal_register_of_legislation:F2007B00391:body:0:p8
Version: federal_register_of_legislation:F2007B00391
Segment Type: other
Provision Reference: 
Character Range: 19117–21973

research has shown that crazy ants have little impact on canopy insects, it is possible that the ants may reduce insect populations, the primary prey of the Hawk-Owl. In the recent Risk Watch List compiled for the Christmas Island National Park and Conservancy, the crazy ant invasion was rated as an Extreme Risk to biodiversity and conservation values, with catastrophic consequences of failure to implement effective control measures.

Parks Australia North field workers and assistants conducted an island-wide ant survey during the months May-August, 2001. This survey was designed by Centre for the Analysis and Management of Biological Invasions, Monash University (CAMBI). Of 972 sites surveyed; 741 surveyed points fell in natural forest. Crazy ants were recorded at 46.7% (346/741) of sites in natural forest. Super-colony densities were recorded at 22.7% (168/741) of sites in natural forest. Using these survey points as a representative sample of the forest, it was estimated that 2,379 hectares of the estimated 10,492 hectares of forest on the island was infested with crazy ants at super-colony densities (Orchard et al. 2002). Crazy Ants are more commonly found in Marginal Rainforests and less commonly found in Primary Rainforests. Primary Rainforests make up most of the natural forests on the island plateau and 31% of census sites in natural forest, but contained only 6.5% of supercolony records (Orchard et al. 2002).

In September 2002 an aerial baiting program was undertaken, with all known supercolonies treated with insecticide. Results so far indicate that the program was successful in controlling supercolonies over 2500 hectares of Christmas Island. Crazy ants are still present in low densities on Christmas Island. However it must be noted that despite this action, further high densities of crazy ants may establish in the terrace forests without warning. PAN staff will continue to monitor any new supercolony formation and treat by hand baiting over the next few years.

Disease
A serious threat to all island birds is the introduction of new disease. Island birds have often evolved in the absence of diseases common in continental bird faunas and the introduction of such diseases to island birds can be disastrous. An example of this is the introduction of avian malaria to Hawaii, which caused the extinction of almost the entire endemic bird fauna from below 600 m altitude, and was probably the main cause of the total extinction of several bird species (Hay 1986). The range of many surviving species was severely reduced and fragmented which in turn markedly increased their chances of extinction. Avian malaria arrived with the accidental introduction of a new species of mosquito (Hay 1986). Christmas Island is very vulnerable to the accidental introduction of new disease. In 1994 a quarantine barrier was