Document ID: chunk:federal_register_of_legislation:F2007B00392:body:0:p3
Version: federal_register_of_legislation:F2007B00392
Segment Type: other
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Character Range: 5472–8200

are known on Christmas Island: the golf course, cemetery and dryers colonies (Figure 1). Stokes (1988) reported that the golf course colony covered c. 40 ha, the cemetery colony c. 65 ha, and the dryers colony c. 66 ha.

Gibson-Hill (1947) estimated the total breeding population to be 1000-1500 pairs. In 1972, the population almost certainly numbered fewer than 2000 pairs (Nelson 1972), and in 1975 it was claimed to comprise fewer than 1000 pairs and to be declining (Nelson 1975). The most recent estimate was of 1620 pairs (Stokes 1984). All the above figures except Stokes (1988) were not based on surveys. The Stokes estimate was based on a three-year count of nests in the golf course colony and estimations of the number of nests at the other two sites (T. Stokes pers. comm.). A census of nest sites in the golf course colony in 1985 revealed that it contained c. 854 occupied nests during the time of peak nest numbers in June/July (Stokes 1988). There is no historical or current census data on the numbers of nests in either the cemetery colony or the dryers colony, although it is possible the dryers colony may no longer be used for nesting (see Threats section). Further data is required on the habitat requirements for Christmas Island Frigatebird breeding and on the use of all nesting colony areas.

Biology
Frigatebirds are a group of seabirds that are adapted morphologically for a highly specialized type of aerial feeding which affects their entire breeding ecology and behaviour. All have extremely prolonged breeding cycles. Frigatebirds in general, do not remain faithful to the same mate or nest site from year to year. Each new breeding effort involves setting up a new territory/nest site, and finding a new mate (Nelson 1975). There is no information on the nest site or mate fidelity of Christmas Island Frigatebirds, but they are probably similar to other frigatebirds.

It requires at least 15 months for a pair of Christmas Island Frigatebirds to raise one offspring to independence, although it is not known whether both partners are required for the entire period. Both Greater Frigatebirds and Lesser Frigatebirds share parental duties and only raise one offspring every two years. However, Magnificent Frigatebird (F. magnificens) males cease parental duties when the young are three to four months of age, leaving the females to raise the young to independence. As a result, males breed every year and the females every second year, and there is a skewed sex ratio (Diamond 1972). In Christmas Island Frigatebirds, females tend to feed the older juveniles more than males do (Gibson-Hill 1947, Marchant & Higgins 1990), but males have been recorded feeding free-flying young that were