The Christmas frigate bird is a very large, mostly black seabird with a glossy green sheen to feathers of the head and back. Females are larger than males; they have a white breast and belly, a narrow white collar around the lower neck and a whitish bar across the upperwing. Males are dark all over apart from a white patch on the lower abdomen. They have a red gular pouch, which becomes more vibrant in the breeding season and is inflated during mating displays. Juveniles have more mottled feathers on their upper-parts, a pale fawn head, white throat and a russet necklace. They take around four years to gain adult plumage.
Did You Know
These rare seabirds are known to forage for food up to hundreds, and sometimes thousands of kilometers away from their colony. One has been documented undertaking a non-stop, 26-hour flight, covering 4000 km flying from Christmas Island via Sumatra and Borneo then back. They are also known for aerial piracy from Sea Bobbies.
Scientific Classification
| Kingdom | Animalia |
| Phylum | Chordata |
| Class | Aves |
| Order | Pelecaniformes |
| Family | Fregatidae |
| Genus | Fregata |
| Species | Fregata andrewsi |
Other Names
| English | Andrew's Frigatebird |
| French | Frégate d'Andrews |
Status
The Christmas frigatebird is classified as Critically Endangered (CR) on the IUCN Red List 2007, and listed on Appendix I of CITES.
Population
The most recent population census indicates a population of 2,400-4,800 mature individuals (2003), roughly equivalent to 3,600-7,200 individuals in total.
Habitat
Although these birds do not settle on the water, they inhabit the open ocean, returning to land only to roost and breed. Both nesting and roosting occur on a small area of Christmas Island, in tall forest close to the shore. Nesting sites are preferentially in the lee of the prevailing southeast winds
Range
The Christmas frigate bird is found in the northeast Indian Ocean, these birds are only known to breed on Christmas Island. The distribution of birds at sea is not well documented but they may wander widely and are known from the coasts of Indonesia, Malaysia, Thailand and northern Australia.
Biology
Males Christmas frigate birds begin their mating displays in late December, inflating their scarlet throat pouches during courtship. Egg laying occurs between March and May and nests are positioned high in tall forest trees. A single egg is laid and both parents take it in turns during the 50 to 54 day incubation period; fledglings can remain dependent on their parents for six to seven months after their first flight.
The Christmas frigate bird feeds mainly on flying fish and cephalopods (such as squid), which are scooped from the surface of the water. A proportion of its food is obtained by harassing other seabirds such as red-footed boobies, until they are forced to regurgitate their meal.
Threats
Habitat destruction and human predation have been the major causes of population decline in the past; dust pollution from phosphate mine driers caused one major nesting site to be abandoned. Dust suppression equipment has since been installed and human predation has ceased since this species has been protected. Birds that have been displaced in the past may now be using sub-optimal habitat, which could pose a threat to their survival. The Christmas frigate bird is confined to a few breeding colonies on a single island and this, together with their low reproductive rate, makes the population alarmingly vulnerable to any chance event.
A possible threat is the introduced yellow crazy ant Anoplolepis gracilipeswhich formed super-colonies during the 1990s and spread rapidly to cover about 25% of the island or about 3,400 ha. Control measures have so far been unable to eradicate this non-native species, but to date frigate birds have not apparently been adversely affected by them. However, ant super-colonies alter island ecology by killing the dominant life-form, the red crab Gecaroidea natalis, and by farming scale insects which damage the trees, which could be a reason for population decline.
Conservation Measures
CITES Appendix I. Listed as vulnerable under the Environment Protection and Biodiversity Conservation Act 1999. The Christmas Island National Park was established in 1980, and has since been extended to include two of the three current breeding colonies (90% of the population). A recovery plan has been completed and a study using satellite telemetry to study movements has been underway since 2005. A control programme for A. gracilipes was initiated after 2000, including aerial baiting in 2002, and effectively eliminated the ant from 2,800 ha of forest (95% of its former extent). However, the ant population continued to increase, covering upwards of 500 ha by 2006. Despite continued control efforts, ants remained persistent in 2009, and perpetual baiting may be the only means of controlling them. Efforts are underway to find alternative bait that is not toxic to invertebrates on the island. Plans have been established to control the scale bugs that the ants tend for their sugar secretions in order to reduce this food supply, but there remains no evidence that they are adversely affecting frigate bird colonies.
References
http://en.wikipedia.org/wiki/Christmas_Frigatebird
http://www.birdlife.org/datazone/speciesfactsheet.php?id=3847
http://www.australiangeographic.com.au/society/fight-for-the-christmas-island-frigatebird.htm
http://orientalbirdimages.org/search.php?Bird_ID=1175
http://www.christmas.net.au/parks/birds/birds_of_christmas_island.htm