Males begin their mating displays in late December (4), inflating their scarlet throat pouches during courtship (2). Egg laying occurs between March and May and nests are positioned high in tall forest trees (6). A single egg is laid and both parents take it in turns during the 50 to 54 day incubation period; fledglings can remain dependant on their parents for six to seven months after their first flight (4). These birds feed mainly on flying fish and cephalopods (such as squid), which are scooped from the surface of the water (6). A proportion of their food is obtained by harassing other seabirds such as red-footed boobies (Sula sula), until they are forced to regurgitate their meal (4).

The Christmas frigatebird is a very large, mostly black seabird with a glossy green sheen to feathers of the head and back (4). Females are larger than males (5); they have a white breast and belly, a narrow white collar around the lower neck and a whitish bar across the upperwing (4). 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 (4). Juveniles have more mottled feathers on their upper-parts (2), a pale fawn head, white throat and a russet necklace (4). They take around four years to gain adult plumage (4).

Christmas I.; ranges to s China Sea and Australia.

North East Indian Ocean

This species is endemic as a breeding species to Christmas Island (to Australia). In 2003 it was estimated that there were 1,171 (± 58) breeding pairs. The number of nests was probably between 3% and 16% lower in 2003 than 1985 (one generation; 1985 estimates ranging from 1,320-1,620 pairs⁴), but this may not be an accurate indication of population trends. Due to biennial breeding, the total breeding population is between one and two times the number of pairs nesting per annum (i.e. 1,200-2,400 pairs). An historical review of the extent and decline of the four sub-colonies suggests that the pre-settlement population was about 6,300 breeding pairs per annum, but declined to 4,500 by 1910, 3,500 by 1945, 2,500 by 1967, and 1,500 by 1978. If this reconstruction is correct, then the population declined by about 66% over three generations between 1945 and 2003³. In 2003 there were four sub-colonies (since reduced to three) covering an area of c.49 ha^3,4. The Flying Fish Cove sub-colony probably contained c.50 ha of habitat in 1887; it underwent an almost complete decline in the early 1900s, and in 2003 it contained only c.10 ha of habitat and two nests. The Dryers sub-colony underwent an almost complete decline by the 1970s, and in 2003 contained c.62 ha of habitat and 20 nests. The Golf Course sub-colony lost c.13 ha (25%) in the 1940s, and in 2003 it contained c.25 ha of habitat and an estimated 828 (± 42) nests. The Cemetery sub-colony contained 46 ha of habitat and an estimated 321 (± 15) nests in 2003³. Surveys in 2004 showed a significant increase in number of nests, with 767 nests in 244 nest trees at the largest colony⁹ but surveys in 2005 showed a return to 2003 levels, suggesting that inter-annual variation rather than population growth explains the increase in numbers in 2004. Breeding and non-breeding birds have been recorded foraging at low densities in the Indo-Malay Archipelago⁷ over the Sunda Shelf to the South China Sea, the Andaman Sea, the Sulu Sea, off south-west Sulawesi, and in the Gulf of Thailand^13,14,16,17, commuting directly over Java in the process⁶. When not breeding the species ranges widely across the seas of South-East Asia to Indochina and south to northern Australia⁴, but its status in the Indian Ocean to the west is less well known.

Christmas Island frigatebirds gets their name from the fact that they breed exclusively on Christmas Island, an island off the northwestern coast of Australia in the Indian Ocean. When not breeding, Christmas Island frigatebird range widely throughout Southeast Asia and the Indian Ocean, and are occasionally spotted near Sumatra, Java, Bali, Borneo, the Andaman Islands, and the Keeling Islands.

Biogeographic Regions: oriental (Native ); australian (Native ); indian ocean (Native )

Historic Range:
East Indian Ocean

Found in the northeast Indian Ocean, these birds are only known to breed on Christmas Island (4). 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 (6) and northern Australia (4).

Christmas Island frigatebirds are large black sea birds with deeply forked tails and long hooked bills. Both sexes share a distinct white belly patch and pale bars on the upperwing. Females are larger than their male counterparts, with weights of 1550 g and 1400 g respectively. Males have a red gular pouch and the bill is dark grey. Females have a black throat and a pink bill. Females have a white collar and the belly patch extends onto the breast as well as the the axillaries as a spur. Juveniles have a distinct blue bill as well as a pale yellow head, the body is mostly brown with a blackish tail.

Range mass: 1550 (high) g.

Range length: 89 to 100 cm.

Range wingspan: 206 to 230 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: female larger; sexes colored or patterned differently

breeding on Christmas isl.

Habitat and Ecology

Systems

• Terrestrial
• Marine

Christmas Island frigatebirds can be found in the tropical and subtropical waters of the Indian Ocean. Most of their time is spent at sea, the minimal time that is spent on land is for roosting and breeding. This species will roost communally and alongside other frigatebird species as well. Roosting and breeding sites are preferably high, as Christmas Island frigatebirds experience great difficulty taking of from perches less than 3 meters in height. They breed exclusively in the low dry forest of Christmas Island. This species prefers warmer, low salinity waters.

Habitat Regions: tropical ; terrestrial ; saltwater or marine

Terrestrial Biomes: forest

Aquatic Biomes: pelagic ; coastal

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 (4). Nesting sites are preferentially in the lee of the prevailing southeast winds (4).

Christmas Island frigatebirds are strictly surface feeders. They are largely piscivorious, feeding on flying fish, jellyfish, squid, large plankton, and fishery by-catch and offal. Being strictly surface skimmers, they generally only immerse their bill but sometimes they do immerse their entire head. They have been known to take eggs from other nests and prey on the young of other frigatebirds. They are sometimes called 'pirate birds' in reference to their habit of harassing other seabirds into releasing or regurgitating their prey, which they then take.

Animal Foods: birds; fish; eggs; mollusks; aquatic crustaceans; cnidarians; zooplankton

Primary Diet: carnivore (Piscivore , Molluscivore , Eats other marine invertebrates)

Christmas Island frigatebirds are important predators of marine vertebrates and invertebrates where they occur.

Other Christmas Island frigatebirds may prey on eggs and nestlings. Otherwise, there are few natural predators of frigatebirds. Nesting colonies are in isolated and inaccessible areas and are protected by the nesting birds.

Christmas Island frigatebirds use visual cues for mating, as when the males inflate their red gular pouches to attract females. They also use a variety of vocalizations to communicate in breeding colonies. Males and females distinctive vocalizations to communicate with each other and with their offspring.

Communication Channels: visual ; acoustic

The mortality rate among Adult Christmas Island frigatebirds is 4% yearly, giving them an average lifespan of 25.6 years, it is speculated that they may live to reach ages of 40 to 45 years.

Typical lifespan

Status: wild: 45 (high) years.

Average lifespan

Status: wild: 25.6 years.

Generally Christmas Island frigatebirds do not mate with partners from previous years; each season new mates are chosen as well as new nesting sites. In late December males select display sites, where they inflate their bright red gular pouch to attract females. Pairs are usually formed by the end February. The nest is then built at the display site. Christmas Island frigatebirds are colonial nesters and there are only 3 known colonies on the island, Golf Course, Dyers, and Cemetery. Christmas Island frigatebirds seem to be more selective in their nest sites than the other members of the genus Fregata. They prefer to nest in sites sheltered from high winds to ensure safe landings. Nest sites of Christmas Island frigatebirds are situated under the top branches of a chosen tree. This species is highly selective in the choice of tree species used for nesting, studies of the golf course colony have shown that Terminalia catappa and Celtis timorensis are the preferred species of nesting tree comprising 65.5% of the trees chosen. Nesting also occurs in some species of Ficus, but is less common. It is also noted that all of these tree species occur throughout the island, yet breeding is restricted to the 3 main colonies.

Mating System: monogamous

It takes over 40 days for a pair to incubate a single egg. The young generally hatch anywhere from mid-April to late-June. The offspring are very slow growing but seem to grow quicker than the young of other frigatebird species. It takes fifteen months to raise one chick, so breeding occurs only every 2 years, though it is not known whether both parents are required for the entire time. Males may attempt to mate every year.

Breeding interval: Pairs breed every other year, it is not yet confirmed whether or not males attempt to breed every season.

Breeding season: The breeding season is estimated to last 9 to 10 months.

Average eggs per season: 1.

Average time to hatching: 40 days.

Average time to independence: 15 months.

Range age at sexual or reproductive maturity (female): 5 to 7 years.

Range age at sexual or reproductive maturity (male): 5 to 7 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Fifteen months are needed for a pair to raise one young to independence. Both parents help in incubating the egg and feeding of the chick when hatched. Generally the older juveniles are fed by the female parent more frequenty than the male, although there have been observations of males feeding free-flying offspring at least 8 months old. About 15 to 20% the eggs that are laid fledge young. Some groups are able to raise 60% of nestlings successfully to fledging. It is estimated that a breeding pair takes twenty to twenty five years of breeding attempts, or more, to replace themselves.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2009
  Critically Endangered
• 2008
  Critically Endangered
• 2007
  Critically Endangered
• 2005
  Critically Endangered
• 2004
  Critically Endangered
• 2000
  Critically Endangered
• 1996
  Vulnerable
• 1994
  Vulnerable

As of 1985 the breeding population of Christmas Island frigatebirds was censused at 1,620 pairs and in 2003 breeding pair numbers were estimated to be 1,171 (+/- 58). Other estimations of 4,500 for the entire population have been made, although difficulty in distinguishing immature Fregata andrewsi from other species of Fregata may make non-breeding population estimates inaccurate. Along with the population estimates done in 1985, estimations of nest numbers were also done, with 100 nests at the Dryers colony, 370 at the Cemetery colony and 850 at the Golf Course colony. Numbers have since decreased at Dryers to 30 nests. As of 1987 there were 4 known colonies, the 3 previously mentioned and the fourth being the Flying Fish Cove colony but in 2003 only 2 nests were present.

One of the main threats to the success of Christmas Island frigatebirds is the yellow crazy ant (Anoplolepis gracilipes). These ants form super-colonies that can stress trees to such an extent that they die, making the preferred nesting sites of Christmas Island frigatebirds unavailable. It is speculated that higher incidences of death from groundings occurs when the birds are grounded in these super-colonies. Due to its limited breeding range and preferred nesting sites, population numbers of Christmas Island frigatebirds are very sensitive to any changes in tree numbers.

Christmas Island frigatebirds are considered critically endangered by the IUCN and are on the CITES Appendix I.

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: appendix i

State of Michigan List: no special status

IUCN Red List of Threatened Species: critically endangered

Current Listing Status Summary

Status: Endangered
Date Listed: 06/14/1976
Lead Region: Foreign (Region 10) 
Where Listed:


Population detail:

Population location: entire
Listing status: E

For most current information and documents related to the conservation status and management of Fregata andrewsi , see its USFWS Species Profile

Classified as Critically Endangered (CR) on the IUCN Red List 2007 (1), and listed on Appendix I of CITES (3).

Population

Population Trend

Major Threats

Habitat destruction and human predation have been the major causes of population decline in the past (6); dust pollution from phosphate mine driers caused one major nesting site to be abandoned (4). Dust suppression equipment has since been installed and human predation has ceased since this species has been protected (4). Birds that have been displaced in the past may now be using sub-optimal habitat, which could pose a threat to their survival (4). The Christmas frigatebird is confined to a few breeding colonies on a single island and this, together with their low reproductive rate (4), makes the population alarmingly vulnerable to any chance event.

Conservation Actions

Christmas Island National Park was established in 1989 and contains two of the three current breeding populations (5). Christmas frigatebirds are also protected outside of the park and by Migratory Bird Agreements between Australia and other countries (4). This species remains highly vulnerable however, and the close monitoring of breeding success and population size remains a high priority (4).

There are no known adverse effects of Christmas Island frigatebirds on humans.

The many endemic species of birds found on Christmas Island draws eco-tourist groups of bird watchers. As of 2004 there is a rainforest rehabilitation program and a proposed frigatebird monitoring program that has the potential to provide more employment opportunities on the island.

Positive Impacts: ecotourism ; research and education