Photo Gallery
Streaked Shearwater ( Hoagulhaa )
Dhivehi Name: Miaremu Dhooni
English Name: Streaked Shearwater
Scientific Name: Calonectris leucomelas
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The Streaked Shearwater, Calonectris leucomelas is a species of seabird. The bird is 48 cm in size, with a 122 cm wingspan.
This species is pelagic, but also occurs in inshore waters. It occurs in the Pacific Ocean, nesting in Japan and many of its offshore islands. After breeding, the Streaked Shearwater will migrate toward southern Australia. It has been reported well off the west coast of the United States.
The Streaked Shearwater feds mainly on fish and squid. It does follow fishing boats, attracted to anchovy crawls off Japan.
Streaked Shearwater uses burrows to nest in. It prefers forested hills.
This bird is abundant and widespread, however some mortality occurs through becoming entangled in fishing nets, and from some predation by cats and rats. In addition, it is harvested by some traditional endemic human cultures.
Gull-billed Tern (Kanifulhu dhooni)
English Name: Gull-billed Tern
Scientific Name: Gelochelidon nilotica
Gull-billed Tern, Gelochelidon nilotica, formerly Sterna nilotica (Bridge et al., 2005), is a seabird of the tern family Sternidae.
It breeds in warmer parts of the world in southern Europe (and a very small isolated population in northern Germany and Denmark), temperate and eastern Asia, both coasts of North America, eastern South America and Australia. This bird has a number of geographical races, differing mainly in size and minor plumage details.
All forms show a post-breeding dispersal, but the northern breeders are most migratory, wintering south to Africa, the Caribbean and northern South America, southern Asia and New Zealand.
his species breeds in colonies on lakes, marshes and coasts. It nests in a ground scrape and lays two to five eggs.
This is a somewhat atypical tern, in appearance like a Sterna tern, but with feeding habits more like the Chlidonias marsh terns, Black Tern and White-winged Tern. It used to be grouped in the genus Sterna but is now placed on its own in the genus Gelochelidon.
The Gull-billed Tern does not normally plunge dive for fish like the other white terns, but feeds on insects taken in flight, and also often hunts over wet fields, to take amphibians and small mammals, as well as small birds.
This is a fairly large and powerful tern, similar in size and general appearance to a Sandwich Tern, but the short thick gull-like bill, broad wings, long legs and robust body are distinctive. The summer adult has grey upperparts, white underparts, a black cap, strong black bill and black legs. The call is a characteristic ker-wik.
In winter, the cap is lost, and there is a dark patch through the eye like a Forster's Tern or a Mediterranean Gull. Juvenile Gull-billed Terns have a fainter mask, but otherwise look much like winter adults.
Juvenile Sandwich Terns have a short bill, and are frequently mistaken for Gull-billed Tern where the latter species is uncommon, such as North Sea coasts.
The Gull-billed Tern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.
Wilson's Storm-petrel (kadhukabaa)
English Name: Wilson's Storm-petrel
Scientific Name: Oceanites oceanicus
The Wilson's Storm-petrel (Oceanites oceanicus), also known as Wilson's Petrel, is a small seabird of the storm-petrel family Hydrobatidae. It is one of the most abundant bird species in the world.
The Wilson's Storm-petrel breeds on the Antarctic coastlines and nearby islands such as the South Shetland Islands. It nests in colonies close to the sea in rock crevices or small burrows in soft earth and lays a single white egg. This storm-petrel is strictly nocturnal at the breeding sites to avoid predation by gulls and skuas, and will even avoid coming to land on clear moonlit nights. Like most petrels, its walking ability is limited to a short shuffle to the burrow.
The Wilson's Storm-petrel spends the rest of the year at sea, and moves into the northern oceans in the southern hemisphere's winter. It is much more common in the north Atlantic than the Pacific. It is strictly pelagic outside the breeding season, and this, together with its remote breeding sites, makes Wilson's Petrel a difficult bird to see from land. Only in severe storms might this species be pushed into headlands.
The Wilson's Storm-petrel is common off eastern North America in the northern summer and the seasonal abundance of this bird in suitable European waters has been revealed through pelagic boat trips, most notably in the area of the Isles of Scilly, Great Britain.
The Wilson's Storm-petrel is a small bird, 16-18.5 cm in length with a 38-42 cm wingspan. It is slightly larger than the European Storm-petrel. It is essentially dark brown in all plumages, except for white rump. It differs from the that species by its pale bar on the upper wing, plain underwings and longer legs.
It has a more direct gliding flight than Storm Petrel, but shares the habit of pattering on the water surface as it picks planktonic food items from the ocean surface, though with more upraised wings. Like European Storm-petrel, it is highly gregarious, and will also follow ships. A soft peeping noise is often heard while the birds are feeding.
The name commemorates the Scottish-American ornithologist Alexander Wilson.
Widespread throughout its large range, the Wilson's Storm-petrel is evaluated as Least Concern on the IUCN Red List of Threatened Species.
White-faced Storm-petrel (Moonuhudhu kadhukabaa)
English Name: White-faced Storm-petrel
Scientific Name: Pelagodroma marina
White-faced Storm-petrel, Pelagodroma marina also known as White-faced Petrel is a small seabird of the storm-petrel family. It is the only member of monotypic genus, Pelagodroma.
The White-faced Storm-petrel breeds on remote islands in the south Atlantic, such as Tristan da Cunha and also Australia and New Zealand. There are north Atlantic colonies on the Cape Verde Islands, Canary Islands and Savage Islands. It nests in colonies close to the sea in rock crevices and lays a single white egg. It spends the rest of the year at sea.
The White-faced Storm-petrel is strictly pelagic outside the breeding season, and this, together with its often-remote breeding sites, makes this petrel a difficult bird to see from land. Only in severe storms might this species be pushed into headlands. There have been a handful of western Europe records from France, Great Britain and The Netherlands.
This storm-petrel is strictly nocturnal at the breeding sites to avoid predation by gulls and skuas, and will even avoid coming to land on clear moonlit nights. Like most petrels, its walking ability is limited to a short shuffle to the
The White-faced Storm-petrel is 19-21 cm in length with a 41-44 cm wingspan. It has a pale brown to grey back, rump and wings with black flight feathers. It is white below, unlike other north Atlantic petrels, and has a white face with a black eye mask like a phalarope. Its plumage makes it one of the easier petrels to identify at sea.
It has a direct gliding flight and will patter on the water surface as it picks planktonic food items from the ocean surface. It is highly gregarious, but does not follow ships.
Widespread throughout its large range, the White-faced Storm-petrel is evaluated as Least Concern on the IUCN Red List of Threatened Species.
Flash-footed Shearwater (Maahoagulha)
English Name: Flash-footed Shearwater
Scientific Name: Puffinus carneipes
The Flesh-footed Shearwater, Puffinus carneipes, is a small shearwater. Its plumage is black. It has pale pinkish feet, and a pale bill with a black tip. Together with the equally light-billed Pink-footed Shearwater, it forms the Hemipuffinus group, a superspecies which may or may not have an Atlantic relative in the Great Shearwater (Austin, 1996; Austin et al., 2004). These are large shearwaters which are among those that could be separated in the genus Ardenna (Penhallurick & Wink, 2004).
It breeds in colonies, and has two main breeding areas: one in the South West Pacific Ocean includes Lord Howe Island (20,000 to 40,000 pairs) and northern New Zealand (50,000 to 100,000 pairs); the other is along the coast of Western Australia from Cape Leeuwin to the Recherche Archipelago. Another 600 pairs breed on St Paul Island in the Indian Ocean. It occurs as a summer visitor in the North Pacific Ocean as far north as British Columbia. Flesh-footed shearwaters have been sighted in the Central-North Pacific, above the main Hawaiian Islands as well.
Audubon's Shearwater (Dhivehi Hhoagulhaa)
English Name: Audubon's Shearwater
Scientific Name: Puffinus Iherminieri
Audubon's Shearwater, Puffinus lherminieri, is a common tropical seabird from the family Procellariidae. Sometimes called Dusky-backed Shearwater[1], the scientific name of this species commemorates the French naturalist Félix Louis L'Herminier.
Certain populations are also known as Baillon's Shearwater or Tropical Shearwater, Bannerman's Shearwater, Mascarene Shearwater and Persian Shearwater; some of these are considered distinct species by various authors[1]. If they are all placed in P. lherminieri, the North Atlantic Little Shearwater (otherwise often separated as P. baroli) is generally included here too. Thus, these small shearwaters form a cryptic species complex.
Description
Audubon's Shearwaters are on average 30 cm (12 in) in length—about half the size of the Greater Shearwater ("Puffinus" gravis)—and weigh 170 g. There is some variation between populations and the normal size and weight range is 27[verification needed]–33 cm and 150–230 g. The wingspan is 64–72 cm, the tail is around 8.5 cm long, the exposed culmen measures 3 cm or slightly less, and the tarsus is around 4 cm in length.[2] In general appearance, it is a small shearwater, black above and white below and hard to distinguish from its relatives at first glance.[1]
The upperparts, rectrices and undertail coverts are blackish-brown, as are at least the distal undersides of the remiges, but sometimes the entire feathers. The rest of the underparts are white, as is the head below eye level. The iris is dark, the feet are dull pink with a black wash and black toenails[2], and the bill is grey, darker towards the tip, and with a pinkish hue.[1]
Males and females look alike. Immature birds do not have a distinct plumage, while the nestlings are covered with down feathers, grey above and whitish on the belly.[1]
It can be confused with the Manx Shearwater (P. puffinus), which has white undertail coverts and in direct comparison a longer bill. Other similar-looking species are usually completely allopatric, though the largely subantarctic Little Shearwater (P. assimilis) may occasionally range into waters where P. lherminieri is normally found. It has more white on the face and underwing, a smaller bill and greyish-blue feet.[1]
Its twittering calls and mewing are often only heard at night in the breeding colonies.
Range and ecology
If not split into several species, Audubon's Shearwater ranges across the Indian Ocean north to the Arabian Sea, throughout the northwest and central Pacific, in the Caribbean, and parts of the eastern Atlantic. It is a species of tropical waters; only some Atlantic populations and Bannerman's Shearwater of the Ogasawara Islands occur farther north. Unlike the larger shearwaters, adult Audubon's Shearwaters are not thought to wander much or undertake great migrations, although their young birds do so before breeding, and western Indian Ocean birds may gather in large numbers at the upwelling zone in the Arabian Sea.[1]
It is adaptable as regards its preferred marine habitat; it can be found in pelagic, offshore and inshore waters. It feeds in a variety of methods, mainly diving out of flight, plunging underwater from a swimming position, and picking up food less than a bill's length underwater while "pattering" as if it were walking across the waves. It eats small fish, squid and planktonic crustaceans. Unlike other shearwaters, it is not commonly a ship-follower, though it may attend small fishing boats; it is also sometimes met with as part of a mixed-species feeding flock. [1]
The species is colonial, nesting in small burrows and crevices in rocks and on earthy slopes on atolls and rocky islets. The breeding season varies according to location and subspecies, but how precisely is not very well-studied[3]. Both parents share the responsibility of incubating the single white egg (measurements of 52.5 by 36.2 mm and a weight of 37 g have been recorded for one specimen of average size[2]), each incubating for periods of 2 to 10 days until the egg hatches after 49-51 days of incubation. The nestlings are brooded for half a week to one week, after which time the parents will leave it mostly alone in the burrow and spend most of their time foraging and feeding their voracious offspring, which become very fat. Time from hatching to fledging is 62-75 days. Audubon's Shearwaters take about 8 years to reach breeding age. As typical for Procellariiformes they are long-lived for their size, one bird ringed as an adult was still alive 11 years later; it must have been more than 15 years old at that time.[1]
While some small populations are threatened, the species as a whole (in the present sense, i.e. unsplit) is not considered to be globally threatened.[4]
Systematics
Audubon's Shearwater belongs to the Puffinus sensu stricto group of mid-sized and small shearwaters, which is related to the genus Calonectris. The taxonomy of this species is extremely confusing. It is occasionally listed as a subspecies of P. assimilis (the Little Shearwater), but they do not appear to be that closely related. Rather, P. lherminieri seems to belong to an ill-resolved clade also including such species as the Little Shearwater, the Manx Shearwater (P. puffinus) or the Black-vented Shearwater (P. opisthomelas).[5]
The little-known Heinroth's Shearwater (P. heinrothi) is sometimes considered a subspecies of either Audubon's or the Little Shearwater. Though it is likely to be another member of that close-knit group, its actual relationships remain uncertain due to lack of specimens.
Audubon's Shearwater itself has around 10 subspecies. Several have at one time or another been suggested to constitute separate species. For example, the Galápagos Islands population has turned out to be a very distinct species, the Galápagos Shearwater (P. subalaris); it is apparently related to the Christmas Shearwater (P. nativitatis) and together with it constitutes an ancient lineage without other close relatives in the genus. Other taxa were initially assigned to the Little Shearwater and later moved to Audubon's. Analysis of mtDNA cytochrome b sequence data[7] – which is of somewhat limited value in procellariiform birds however
Wedge-tailed Shearwater (Bodu Hoagulhaa)
English Name: Wedge-tailed Shearwater
Scientific Name: Puffinus pacificus
The Wedge-tailed Shearwater, Puffinus pacificus is a medium-large shearwater in the seabird family Procellariidae. It is one of the shearwater species that is sometimes referred to as a Muttonbird, like the Sooty Shearwater of New Zealand and the Short-tailed Shearwater of Australia. It ranges across from throughout the tropical Pacific and Indian Ocean roughly between latitudes 35°N and 35°S. It breeds in islands such as off Japan, the Islas Revillagigedo, the Hawaiian Islands, the Seychelles and off Western Australia.
Description
The Wedge-tailed Shearwater is the largest of the tropical shearwaters. There are two colour morphs of the species, dark and pale; the pale morphs predominate in the North Pacific, the dark morph elsewhere. However, both morphs exist in all populations, and bear no relation to sex or breeding condition. The pale morph has grey-brown plumage on the back, head and upperwing, and whiter plumage below. The darker morph has the same dark grey-brown plumage over the whole body. The species’ common name is derived from the large wedge-shaped tail, which may help the species glide. The bill is dark and legs are flesh coloured, with the legs set far back on the body (in common with the other shearwaters) as an adaptation for swimming.
This species is related to the pan-Pacific Buller's Shearwater, which differs much in color pattern, but also has a wedgetail and a thin black bill (Austin, 1996; Austin et al., 2004). They make up the Thyellodroma group, a superspecies in the large shearwaters of the proposed genus Ardenna (Penhallurick & Wink, 2004).
Diet
Wedge-tailed Shearwaters feed pelagically on fish, squid and crustaceans. 66% of their diet is fish, of which the most commonly taken is goatfish. It was thought that the species mostly took food from surface feeding, observations of feeding Wedge-tails suggested that contact-dipping, where birds flying close to the surface snatch prey from the water was the most commonly used hunting technique. However, a 2001 study which deployed maximum depth recorders found that 83% of Wedge-tails dived during foraging trips with a mean maximum depth of 14 m and that they could achieve a depth of 66 m (Burger, 2001).
Breeding behaviour
The Wedge-tailed Shearwater breeds in colonies on small tropical islands. Breeding seasons vary depending on location, with synchronised breeding seasons more common at higher latitudes. Northern hemisphere birds begin breeding around February, southern hemisphere birds begin around September. Wedge-tailed Shearwaters display natal philopatry, returning to their natal colony to begin breeding at the age of four.
Wedge-tailed Shearwaters are monogamous, forming a long term pair bond that lasts for several years. Divorce between pairs occurs after breeding seasons that end in failure. Nesting either in burrows or sometimes on the surface under cover. Pairs call frequently as a pair, both to reinforce the pair bond and warn intruders away from their territory. Parents also call to their chicks. The call is long, with an inhaling component (OOO) and exhaling component (err); their Hawaiian name ua’u kani means moaning petrel. Both sexes participate in digging a burrow, or repairing the burrow from last year. Nesting burrows of other species are also used. The breeding season of the Bonin Petrel in Hawaii is timed to avoid that of the Wedge-tail; in years where Bonin Petrel chicks are still in burrows when Wedge-tails return to begin breeding these chicks are killed or evicted. It attends these colonies nocturnally, although non-breeding Wedge-tails are often seen at the surface throughout the day and breeding birds will rest outside their burrows before laying.
Both sexes undertake a prelaying exodus in order to build up energy reserves, this usually lasts around 28 days. A single egg is laid, if that egg is lost then the pair will not attempt another that season. After laying the male usually undertakes the first incubation stint. Both sexes incubate the egg, in stints that can last up to 13 days. Incubation takes around 50 days. After hatching the chick is brooded for up to six days, until it is able to thermoregulate, after which it is left alone in the nest while both parents hunt for food. It is initially fed with stomach oil, an energy rich waxy oil of digested prey created in the parent’s gut; later it is fed both solids and stomach oil. Unlike many procellariids Wedge-tailed Shearwater parents to not alternate long and short trips to provide food, but return regularly. Chicks increase in size to 560 g (larger than the adults) then drop to around 430 g before fledging. Fledging occurs after 103-115 days, after which the chick is independent of the adult.
Masked Booby (Hudhu Maadhooni)
English Name: Masked Booby
Scientific Name: Sula dactylatra
the Masked Booby, Sula dactylatra, is a large seabird of the gannet family, Sulidae. This species breeds on islands in tropical oceans, especially on the Galapagos islands, except in the eastern Atlantic; in the eastern Pacific it is replaced by the Nazca Booby, Sula granti, which was formerly regarded as a subspecies of Masked Booby (Pitman & Jehl 1998, Friesen et al. 2002).\
Description
This is the largest booby, at 81-91 cm length, 152 cm wingspan and 1500 g weight. Adults are white with pointed black wings, a pointed black tail, and a dark grey facemask. The sexes are similar, but the male has a yellow bill, and the female's is greenish yellow; during the breeding season they have a patch of bare, bluish skin at the base of the bill. Juveniles are brownish on the head and upperparts, with a whitish rump and neck collar. The underparts are white. Adult plumage is acquired over two years.
The Masked Booby is silent at sea, but has a reedy whistling greeting call at the nesting colonies. While on the breeding grounds, these birds display a wide range of hissing and quacking notes.
Behaviour
Masked Boobies are spectacular divers, plunging diagonally into the ocean at high speed. They mainly eat small fish, including flying fish. This is a fairly sedentary bird, wintering at sea, but rarely seen far away from the breeding colonies. However, Caribbean birds occasionally wander north to warm southern Gulf Stream waters off the eastern seaboard of the United States. More remarkably, there have been three Western Palaearctic records of Masked Booby, presumably dactylatra, all from Spanish waters, although one of these also entered French territorial areas.
Breeding
It nests in small colonies, laying two chalky white eggs on sandy beaches in shallow depressions, which are incubated by both adults for 45 days. In most cases, the first chick will kill its smaller, weaker sibling after it hatches[1]. Siblicide has been well studied in this species; researchers such as David Anderson have demonstrated that while the boobies can manage to feed two chicks if siblicide is prevented, they do so at a steep penalty to health and future reproductive success.
Brown Booby (Kalhu Maadhooni)
English Name: Brown Booby
Scientific Name: Sula leucogaster
The Brown Booby (Sula leucogaster) is a large seabird of the gannet family, Sulidae. The adult brown booby reaches about 76 cm. (30 in.) in length. Its head and upper body are covered in dark brown, with the remainder being a contrasting white. The juvenile form is gray-brown with darkening on the head, wings and tail. While these birds are typically silent, bird watchers have reported occasional sounds similar to grunting or quacking.
Their heads and backs are black, and their bellies are white. Their beaks are quite sharp and contain many jagged edges. They have short wings and long, tapered tails.
This species breeds on islands and coasts in the pantropical areas of the Atlantic and Pacific oceans. They frequent the breeding grounds of the islands in the Gulf of Mexico and the Caribbean Sea. This bird nests in large colonies, laying two chalky blue eggs on the ground in a mound of broken shells and vegetation. It winters at sea over a wider area.
Brown Booby pairs may remain together over several seasons. They perform elaborate greeting rituals.
Brown Boobies are spectacular divers, plunging into the ocean at high speed. They mainly eat small fish or squid which gather in groups near the surface and may catch leaping fish while skimming the surface. Although they are powerful and agile fliers, they are particularly clumsy in takeoffs and landings; they use strong winds and high perches to assist their takeoffs.
Red-footed Booby (Maa Dhooni)
English Name: Red-footed Booby
Scientific Name: Sula sula
The Red-footed Booby, Sula sula, is a large seabird of the gannet family, Sulidae. They are powerful and agile fliers, but they are clumsy in takeoffs and landings.
Description
The Red-footed Booby is the smallest of all boobies at 71 cm in length and with a 137 cm wingspan. It has red legs, and its bill and throat pouch are coloured pink and blue. This species has two plumage forms. The white phase is mostly white with black on the flight feathers. The brown form is brown with a white belly, rump, and tail. Both forms may occur sympatrically, as in the breeding colony on St. Giles Island, Tobago.
The sexes are similar, and young birds are greyish with browner wings and pink legs.found in tropical islands
Breeding
This species breeds on islands in most tropical oceans. It winters at sea, and is therefore rarely seen away from breeding colonies. It nests in large colonies, laying one chalky blue egg in a stick nest in a tree, which is incubated by both adults for 44-46 days. It may be three months before the young first fly, and five months before they make extensive flights.
Red-footed Booby pairs may remain together over several seasons. They perform elaborate greeting rituals, including harsh squawks and the male’s display of his blue throat.
Diet
Red-footed Boobies are spectacular divers, plunging into the ocean at high speeds to catch prey. They mainly eat small fish or squid which gather in groups near the surface.
Bulwer's Petrel (Kalhu Kandukanbaa)
English Name: Bulwer's Petrel
Scientific Name: Bulweria bulwerii
The Bulwer's Petrel (Bulweria bulwerii) is a small petrel in the family Procellariidae, and is one of two species in the genus Bulweria (Bonaparte, 1843). This bird is named after the Scottish naturalist James Bulwer.
Identification
A large all dark storm-petrel. Has longer wings and tail than other dark storm-petrels such as Swinhoe's Storm-petrel. Flight action is also characterisitic being buoyant and erratic with wings held stiffly bowed. The bill is generally held downwards. Makes a series of stiff flaps before each short twisting glide. Generally keeps close to water surface, circling and zig-zagging when hunting prey. Occasionally fans wedge-shaped tail, otherwise tail looks long and tapering. The pale brown carpal bar is hard to see at any distance.Generally solitary at sea and does not habitually follow ships.
Where and When
Breeding and habitat
Bulwer's Petrel also breeds on islands across the north Pacific from east of China to Hawaii. After breeding, birds disperse to spend the rest of the year at sea, mainly in tropical waters. This species has been recorded in Europe as a rare vagrant to Ireland, Great Britain, Portugal and the Netherlands. It has also appeared as a vagrant in North America, with rare sightings far off the coast of both California and North Carolina.
Lesser Frigatebird (hoara)
English Name: Lesser Frigatebird
Scientific Name: Fregata ariel
The Lesser Frigatebird, Fregata ariel, is a species of frigatebird.
It nests in Australia, among other locations.
There is a single record from the Western Palearctic, from Eilat in the Gulf of Aqaba.
The Lesser Frigatebird or Least Frigatebird (Fregata ariel) is said to be the most common and widespread frigatebird in Australian seas (Lindsey,1986). It is common in tropical seas breeding on remote islands, including Christmas Island in the Indian Ocean in recent years. These birds are most likely to be seen from the mainland prior to the onset of a tropical cyclone, and once this abates they disappear again.
It is the smallest of the three frigatebirds found in Australian waters, measuring about 75cm (30 in) in length. Like all frigatebirds the male has a large red sac on the front of the throat which is inflated during courtship. Courtship display also involves a variety of calls, bill rattling and spreading of the wings. The male is mostly all black save for a white patch on the flank which extends on to the underwing as a spur. Males also have a pale bar on the upper wing. Females have a black head and neck with a white collar and breast as well as a spur extending on to the underwing. The female also has a narrow red ring around the eye. Juveniles and immature birds are more difficult to differentiate but the presence of the spurs of white in the armpits is a helpful distinguishing sign.
Frigate birds are built for flying; they rarely swim and cannot walk but can manage to climb around the trees and bushes in which they nest. They have a very light skeleton and long narrow wings and are masters of the air. Their name probably derives from the fact that they harass other sea birds such as boobies and tropic birds as they return to their nests from feeding, forcing them to disgorge their catch, which is then swooped upon and caught by the frigate birds before it reaches the water below. This practice seems to be more common amongst female frigate birds, but probably only accounts for a fairly small proportion of the diet, which mainly consists of squid and flying fish scooped up from the surface of the sea.
Breeding seems to occur between May and December in in the Australian region. They nest in trees (on Christmas Island) and both sexes contribute to nest building and incubation and feeding of the young. One egg is laid which takes 6-7 weeks to hatch. Fledglings are not left alone for another seven weeks or so for fear that they may be attacked and eaten by other birds including other frigate birds. They remain in the nest for another 6 months or so until fledged but they are cared for and fed by their parents for quite a long time after that.
Great Frigatebird (Maahoara)
English Name: Great Frigatebird
Scientific Name: Fregata minor
The Great Frigatebird (Fregata minor) is a large dispersive seabird in the frigatebird family. Major nesting populations are found in the Pacific (including Galapagos Islands) and Indian Oceans, as well as a population in the South Atlantic.
The Great Frigatebird is a lightly built large seabird up to 105 cm long with predominantly black plumage. The species exhibits sexual dimorphism; the female is larger than the adult male and has a white throat and breast, and the male's scapular feathers have a purple-green sheen. In breeding season, the male is able to distend its striking red gular sac. The species feeds on fish taken in flight from the ocean's surface (mostly flyingfish), and indulges in kleptoparasitism less frequently than other frigatebirds. They feed in pelagic waters within 80 km (50 mi) of their breeding colony or roosting areas.
Taxonomy
Its scientific name of Fregata minor arose because when it was first discovered, it was thought to be a small pelican, and so named Pelecanus minor by the German naturalist Johann Friedrich Gmelin in 1789. Due to the rules of taxonomy, its species name of minor was retained despite being placed in a separate genus. This has led to the discrepancy between minor, Latin for 'smaller' in contrast with its common name. In Hawaii this species is also known as the Iwa.
It is one of five closely related species of Frigatebird that make up their own genus (Fregata) and family (Fregatidae). Its closest relative within the group is the Christmas Island Frigatebird (F. andrewsii).
Description
The Great Frigatebird is a large seabird, measuring 85–105 cm (33.5–41.5 in) with long pointed wings of 205–230 cm (80.5–90.5 in) and long forked tails.[2] Frigatebirds are light, weighing between 1–1.8 kg (2.2–4 lb), and have the highest ratio of wing area to body mass, and the lowest wing loading of any bird. This has been hypothesized to enable the birds to utilize marine thermals created by small differences between tropical air and water temperatures. Male Great Frigatebirds are smaller than females, but the extent of the variation varies geographically.[3] The plumage of males is black with scapular feathers that have a purple-green iridescence when they refract sunlight. Females are black with a white throat and breast and have a red eye ring. Juveniles are black with a rust-tinged white face, head and throat.
Distribution and habitat
The Great Frigatebird has a wide distribution throughout the world’s tropical seas. Hawaii is the northernmost extent of their range in the Pacific Ocean, with around 10,000 pairs nesting mostly in the Northwestern Hawaiian Islands. In the Central and South Pacific, colonies are found on most islands Groups from Wake Island to the Galapagos Islands to New Caledonia with a few pairs nesting on Australian possessions in the Coral Sea. Colonies are also found on numerous Indian Ocean islands including Aldabra, Christmas Island and Mauritius. The small populations in the Western Atlantic Ocean may still persist but are very small if they do. Great Frigatebirds undertake regular migrations across their range, both regular trips and more infrequent widespread dispersals. Birds marked with wing tags on Tern Island in French Frigate Shoals were found to regularly travel to Johnston Atoll (873 km), one was reported in Quezon City in the Philippines. [4] Despite their far ranging birds also exhibit philopatry, breeding in their natal colony even if they travel to other colonies.[5]
Behaviour
Feeding
An immature Great Frigatebird performing a surface snatch on a Sooty Tern chick dropped by another bird
The Great Frigatebird forages in pelagic waters within 80 km (50 mi) of the breeding colony or roosting areas. Flyingfish from the family Exocoetidae are the most common item in the diet of the Great Frigatebird; other fish species and squid may be eaten as well. Prey is snatched while in flight, either from just below the surface or from the air in the case of flyingfish flushed from the water. Great Frigatebirds will make use of schools of predatory tuna or pods of dolphins that push schooling fish to the surface.[6] Like all frigatebirds they will not alight on the water surface and are usually incapable of taking off should accidentally do so.
Great Frigatebirds will also hunt seabird chicks at their breeding colonies, taking mostly the chicks of Sooty Terns, Grey-backed Terns, Brown Noddies and Black Noddies. Studies show that only females (adults and immatures) hunt in this fashion, and only a few individuals account for most of the kills.[7]
Great Frigatebirds will attempt kleptoparasitism, chasing other nesting seabirds (boobies and tropicbirds in particular) in order to make them regurgitate their food. This behaviour is not thought to play a significant part of the diet of the species, and is instead a supplement to food obtained by hunting. A study of Great Frigatebirds stealing from Masked Boobies estimated that the frigatebirds could at most obtain 40% of the food they needed, and on average obtained only 5%.[8]
Breeding
Great Frigatebirds are seasonally monogamous, with a breeding season that can take two years from mating to the end of parental care. The species is colonial, nesting in bushes and trees (and on the ground in the absence of vegetation) in colonies of up to several thousand pairs. Nesting bushes are often shared with other species, especially Red-footed Boobies and other species of frigatebirds.
Both sexes have a patch of red skin at the throat that is the gular sac; in male Great Frigatebirds this is inflated in order to attract a mate. Groups of males sit in bushes and trees and force air into the sac, causing it to inflate over a period of 20 minutes into a startling red balloon. As females fly overhead the males waggle their heads from side to side, shake their wings and call. Females will observe many groups of males before forming a pair bond. Having formed a bond the pair will sometimes select the display site, or may seek another site, to form a nesting site; once a nesting site has been established both sexes will defend their territory (the area surrounding the nest that can be reached from the nest) from other frigatebirds.
Pair bond formation and nest-building can be completed in a couple of days by some pairs and can take a couple of weeks (up to four) for other pairs. Males collect loose nesting material (twigs, vines, flotsam) from around the colony and off the ocean surface and return to the nesting site where the female builds the nest. Nesting material may be stolen from other seabird species (in the case of Black Noddies the entire nest may be stolen) either snatched off the nesting site or stolen from other birds themselves foraging for nesting material. Great Frigatebird nests are large platforms of loosely woven twigs that quickly become encrusted with guano. There is little attempt to maintain the nests during the breeding season and nests may disintegrate before the end of the season.
A single dull chalky-white egg measuring 68 x 48 mm is laid during each breeding season.[9] If the egg is lost the pair bond breaks; females may acquire a new mate and lay again in that year. Both parents incubate the egg in shifts that last between 3–6 days; the length of shift varies by location, although female shifts are longer than those of males. Incubation can be energetically demanding, birds have been recorded losing between 20–33% of their body mass during a shift.
Incubation lasts for around 55 days. Great Frigatebird chicks begin calling a few days before hatching and rub their egg tooth against the shell. The altricial chicks are naked and helpless, and lie prone for several days after hatching. Chicks are brooded for two weeks after hatching after which they are covered in white down, and guarded by a parent for another fortnight after that. Chicks are given numerous meals a day after hatching, once older they are fed every one to two days. Feeding is by regurgitation, the chick sticks its head inside the adults mouth.
Parental care is prolonged in Great Frigatebirds. Fledging occurs after 4–6 months, the timing dependent on oceanic conditions and food availability.[2] After fledging chicks continue to receive parental care for between 150–428 days; frigatebirds have the longest period of post-fledging parental care of any bird. The length of this care depends on oceanic conditions, in bad years (particularly El Niño years) the period of care is longer. The diet of these juvenile birds is provided in part by food they obtained for themselves and in part from their parents. Young fledglings will also engage in play; with one bird picking up a stick and being chased by one or more other fledglings. After the chick drops the stick the chaser attempts to catch the stick before it hits the water, after which the game starts again. This play is thought to be important in developing the aerial skills needed to fish.
Male in flight, Lady Elliot Island, Qld
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