Document ID: chunk:federal_register_of_legislation:F2007B00392:body:0:p9
Version: federal_register_of_legislation:F2007B00392
Segment Type: other
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Character Range: 21205–24029

deep-soil tall-closed forest, which make up most of the natural forests on the island plateau. Deep-soil tall-closed forest made up 31% of census sites in natural forest but only 6.5% of supercolony records (Orchard et al. 2002). Christmas Island Frigatebirds are especially at risk from Crazy Ants because of this concentration of supercolonies on terrace forests where all Christmas Island Frigatebirds nesting habitat occurs. The distribution of Crazy Ant colonies in relation to Christmas Island Frigatebird nesting areas is shown in Figure 1.
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 2500ha 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.

Dust from phosphate dryers.
Part of the phosphate mine, the "Dryers" chimneys were built in the early 1970's and emitted very large amounts of phosphate dust which settled on the downwind terrace forests causing dieback and death to some trees. A major refit has since reduced dust output from around 30kg/cubic metre of exhaust to well below 50mg/cubic metre of exhaust (M. Bennett, CIP, pers. comm).

An island-wide survey of terrace nesting seabirds in May/June 1984 (Stokes 1984) estimated that 100 pairs nested in the dryers colony. A decade later, a brief reconnoitre of the area found fewer than 30 Frigatebird nests between Smith point and Margaret beaches and it was estimated that there would have been at most 50 nests at the peak breeding time (A. Dunn unpub. data).

In 1967, Nelson (pers. comm to Stokes 1988) reported that the dryers and golf course colonies were the two main Christmas Island Frigatebirds nesting areas. Nelson did not note birds nesting in the area now supporting the cemetery colony. This prompted Stokes (1988) to suggest that the cemetery colony may have formed relatively recently from birds displaced from the dryers colony.

Since January 2000 Christmas Island Phosphates have carried out basic monitoring of the utilisation of the "dryers" breeding colony area by all birds including Christmas Island Frigatebirds and there was some suggestion that use of the area by birds generally had increased since the dust emissions were controlled (M. Bennett pers. comm.). However, as of May 2003 there are no Christmas Island Frigatebirds nesting in the area where the old dryers colony was.

Storms
Christmas Island tends to be affected by severe storms every five to ten years. The