Document ID: chunk:federal_register_of_legislation:F2007B00391:body:0:p7
Version: federal_register_of_legislation:F2007B00391
Segment Type: other
Provision Reference: 
Character Range: 16432–19356

shared in common with other recovery plans are identified in the implementation section of this plan.

Recovery Team
The Christmas Island Hawk-Owl Recovery Team should comprise on-island Parks Australia North staff, Shire of Christmas Island, an environment consultant, Department of Transport and Regional Services, and other members as thought appropriate.

Threats to the species

Birds on Islands
Island birds are particularly vulnerable to extinction and a very high number of island birds relative to continental species have become extinct in the past century (Diamond 1985, King 1985). This is because: (i) island birds tend to have smaller population sizes than continental species and small populations are more vulnerable to extinction (Lacy 1987); (ii) island birds have often evolved in the absence of many predators, diseases and competitors and they can be catastrophically affected by the introduction of one of these (King 1985); (iii) there are often no opportunities for dispersal and thus recolonisation on islands, and this factor also predisposes a population to extinction (Lacy 1987); and (iv) there is often less opportunity to make reserves on islands because land area is limited (Diamond 1985). Predators in general are often naturally rare because their prey, other animals, are less abundant than other food resources. Thus island raptors are a particularly vulnerable group of island birds.

Crazy Ants
The exotic invasive yellow crazy ant (Anoplolepis gracilipes) arrived on Christmas Island more than 70 years ago, and is now widespread throughout rainforest (Orchard et al. 2002). The ants can form multi-queened 'super-colonies', in which they occur at very high densities. This has apparently been a relatively recent phenomenon, with the first supercolony discovered in 1989, with further dramatic increases probably beginning around the mid-1990s.

At supercolony densities, the ant is having a devastating impact on the island's ecosystems. Red crabs, robber crabs, blue crabs and most other ground dwelling animals such as reptiles, have been and are continuing to be severely impacted, sometimes to the point of local extinction in heavily infested areas. By eliminating local populations of red crabs, the ants are also having a marked effect on forest composition and structure, and litter dynamics. The feeding activities of the ants and their mutualistic scale insects can stress large trees to the point of death, and appear to be causing canopy dieback in areas of supercolony formation (Orchard et al. 2002). In addition groundings of birds in crazy ant supercolonies would most probably result in the death of the bird. Although 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