Document ID: chunk:federal_register_of_legislation:F2007B00392:body:0:p5
Version: federal_register_of_legislation:F2007B00392
Segment Type: other
Provision Reference: 
Character Range: 10410–13160

about 4% p.a., giving them an average life expectancy of about 25.6 years. He reasoned that some individuals probably live to 40 or 50 years.

Diet
Christmas Island Frigatebirds forage either by scooping up marine organisms or offal floating on the surface of the water or by their piratical habit of harassing other seabirds forcing them to disgorge some of their meal. Their main food is probably flying fish and squid (Gibson-Hill 1947), however they will occasionally take food off land, pick up carrion and offal from beaches, and steal eggs and nestlings. Grasshoppers have also been recorded from stomach contents (Marchant & Higgins 1990). Most nesting adult frigatebirds appear to forage in the waters immediately around the island. Young birds that have not yet reached breeding age and non-breeding adults probably forage much farther afield.

The waters surrounding Christmas Island may be unusually productive. Christmas Island Frigatebird nestlings were fed more frequently than Greater and Lesser Frigatebirds on other islands and grew much faster (Nelson 1972, 1975). Studies of Abbott's Boobys suggested that food availability in the waters surrounding the Christmas Island fluctuate greatly from year to year (Reville at al. 1990).

Habitat Critical to Survival
Christmas Island Frigatebirds can experience great difficulty in becoming airborne and cannot take off from perches less than 3m from the ground (Gibson-Hill 1947). During most of the year the prevailing wind on Christmas Island is the south-east trade winds, and nests are sited preferentially in the lee of the wind or protected (Stokes 1985). Frigatebirds nest under the top branches of trees and require a site that is calm enough to allow them to land safely. In 1994 a few appeared to nest in one or two trees high up the cliff above the road to Smith Point in Flying Fish Cove (A. Dunn unpubl. data). Nelson (1975) noted that they prefer to nest in Sea Almond Terminalia catappa. A survey of the golf course colony in 1983 found that the two species T. catappa and Celtis timorensis comprise 65.5% of all nest trees chosen (Stokes 1985). Ficus sp. trees are also often used for nesting (Marchant & Higgins 1990), but are rarely used in the golf course colony (Stokes 1985). These nest tree species occur right around the island and yet the species nests only in a small area of the island.

Data collected in the mid 1980s by T. Stokes may provide better characterisation of preferred nesting habitat. Analysis of this data is underway. Christmas Island Frigatebirds appear to be more restricted in their choice of nest sites, tending to nest well down on the shore terrace (Gibson-Hill 1947, Nelson 1972), whereas Greater Frigatebirds will also nest on the slope