Great Frigatebird
Encyclopedia
The Great Frigatebird is a large dispersive seabird
in the frigatebird
family
. Major nesting populations are found in the Pacific (including Galapagos Islands
) and Indian Ocean
s, 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.
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 (or 'thief' in Hawaiian
).
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).
The Great Frigatebird is a large seabird and, despite its name, it is the second largest frigatebird, after the Magnificent Frigatebird
. The Great Frigatebird measures 85 to 105 cm (33.5 to 41.3 in) in length with long pointed wings of 205–230 cm (80.5–90.5 in) and long forked tails. The Great Frigatebird weighs from 640–1550 g (1.4–3.4 lb). The frigatebirds 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. 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.
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 Australia
n possessions in the Coral Sea
. Colonies are also found on numerous Indian Ocean
islands including Aldabra
, Christmas Island
, Maldives
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
. Despite their far ranging birds also exhibit philopatry
, breeding in their natal colony even if they travel to other colonies.
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 dolphin
s that push schooling fish to the surface. 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 Tern
s, Spectacled 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.
Great Frigatebirds will attempt kleptoparasitism
, chasing other nesting seabirds (boobies
and tropicbird
s 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%.
, 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 their 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. 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. 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.
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
in the frigatebird
Frigatebird
The frigatebirds are a family, Fregatidae, of seabirds. There are five species in the single genus Fregata. They are also sometimes called Man of War birds or Pirate birds. Since they are related to the pelicans, the term "frigate pelican" is also a name applied to them...
family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
. Major nesting populations are found in the Pacific (including Galapagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
) and Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
s, 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
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
; 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
Flyingfish
Exocoetidae, is a family of marine fish in the order Beloniformes of class Actinopterygii. Fish of this family are known as flying fish. There are about 64 species grouped in seven to nine genera.- Etymology :...
), and indulges in kleptoparasitism
Kleptoparasitism
Kleptoparasitism or cleptoparasitism is a form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food, including stored food...
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 GmelinJohann Friedrich Gmelin
Johann Friedrich Gmelin was a German naturalist, botanist, entomologist, herpetologist and malacologist.- Education :Johann Friedrich Gmelin was born as the eldest son of Philipp Friedrich Gmelin in 1748 in Tübingen...
in 1789. Due to the rules of taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
, its species name of minor was retained despite being placed in a separate genus. This has led to the discrepancy between minor, Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for 'smaller' in contrast with its common name. In Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
this species is also known as the Iwa (or 'thief' in Hawaiian
Hawaiian language
The Hawaiian language is a Polynesian language that takes its name from Hawaii, the largest island in the tropical North Pacific archipelago where it developed. Hawaiian, along with English, is an official language of the state of Hawaii...
).
It is one of five closely related species of Frigatebird
Frigatebird
The frigatebirds are a family, Fregatidae, of seabirds. There are five species in the single genus Fregata. They are also sometimes called Man of War birds or Pirate birds. Since they are related to the pelicans, the term "frigate pelican" is also a name applied to them...
that make up their own genus (Fregata) and family (Fregatidae). Its closest relative within the group is the Christmas Island Frigatebird
Christmas Island Frigatebird
The Christmas Frigatebird or Christmas Island Frigatebird is a frigatebird endemic to the Christmas Islands in the Indian Ocean...
(F. andrewsii).
Physical description
Magnificent Frigatebird
The Magnificent Frigatebird was sometimes previously known as Man O'War, reflecting its rakish lines, speed, and aerial piracy of other birds....
. The Great Frigatebird measures 85 to 105 cm (33.5 to 41.3 in) in length with long pointed wings of 205–230 cm (80.5–90.5 in) and long forked tails. The Great Frigatebird weighs from 640–1550 g (1.4–3.4 lb). The frigatebirds 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. The plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
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. HawaiiHawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
is the northernmost extent of their range in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, with around 10,000 pairs nesting mostly in the Northwestern Hawaiian Islands
Northwestern Hawaiian Islands
The Northwestern Hawaiian Islands or the Leeward Islands are the small islands and atolls in the Hawaiian island chain located northwest of the islands of Kauai and Niihau. They are administered by the U.S. state of Hawaii except Midway Atoll, which has temporary residential facilities and is...
. In the Central and South Pacific, colonies are found on most islands Groups from Wake Island
Wake Island
Wake Island is a coral atoll having a coastline of in the North Pacific Ocean, located about two-thirds of the way from Honolulu west to Guam east. It is an unorganized, unincorporated territory of the United States, administered by the Office of Insular Affairs, U.S. Department of the Interior...
to the Galapagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
to New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
with a few pairs nesting on Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n possessions in the Coral Sea
Coral Sea
The Coral Sea is a marginal sea off the northeast coast of Australia. It is bounded in the west by the east coast of Queensland, thereby including the Great Barrier Reef, in the east by Vanuatu and by New Caledonia, and in the north approximately by the southern extremity of the Solomon Islands...
. Colonies are also found on numerous Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
islands including Aldabra
Aldabra
Aldabra, the world's second largest coral atoll, is in the Aldabra Group of islands in the Indian Ocean that form part of the Seychelles. Uninhabited and extremely isolated, Aldabra is virtually untouched by humans, has distinctive island fauna including the Aldabra Giant Tortoise, and is...
, Christmas Island
Christmas Island
The Territory of Christmas Island is a territory of Australia in the Indian Ocean. It is located northwest of the Western Australian city of Perth, south of the Indonesian capital, Jakarta, and ENE of the Cocos Islands....
, Maldives
Maldives
The Maldives , , officially Republic of Maldives , also referred to as the Maldive Islands, is an island nation in the Indian Ocean formed by a double chain of twenty-six atolls oriented north-south off India's Lakshadweep islands, between Minicoy Island and...
and Mauritius
Mauritius
Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...
. The small populations in the Western Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
may still persist but are very small if they do.
Great Frigatebirds undertake regular migrations
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
across their range, both regular trips and more infrequent widespread dispersals. Birds marked with wing tags
Bird ringing
Bird ringing or bird banding is a technique used in the study of wild birds, by attaching a small, individually numbered, metal or plastic tag to their legs or wings, so that various aspects of the bird's life can be studied by the ability to re-find the same individual later...
on Tern Island in French Frigate Shoals
French Frigate Shoals
The French Frigate Shoals is the largest atoll in the Northwestern Hawaiian Islands. Its name commemorates French explorer Jean-François de La Pérouse, who nearly lost two frigates when attempting to navigate the shoals...
were found to regularly travel to Johnston Atoll
Johnston Atoll
Johnston Atoll is a atoll in the North Pacific Ocean about west of Hawaii. There are four islands located on the coral reef platform, two natural islands, Johnston Island and Sand Island, which have been expanded by coral dredging, as well as North Island and East Island , an additional two...
(873 km), one was reported in Quezon City
Quezon City
Quezon City is the former capital and the most populous city in the Philippines. Located on the island of Luzon, Quezon City is one of the cities and municipalities that make up Metro Manila, the National Capital Region. The city was named after Manuel L...
in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
. Despite their far ranging birds also exhibit philopatry
Philopatry
Broadly, philopatry is the behaviour of remaining in, or returning to, an individual's birthplace. More specifically, in ecology philopatry is the behaviour of elder offspring sharing the parental burden in the upbringing of their siblings, a classic example of kin selection...
, breeding in their natal colony even if they travel to other colonies.
Feeding
Flyingfish
Exocoetidae, is a family of marine fish in the order Beloniformes of class Actinopterygii. Fish of this family are known as flying fish. There are about 64 species grouped in seven to nine genera.- Etymology :...
from the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Exocoetidae are the most common item in the diet of the Great Frigatebird; other fish species and squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
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
Tuna
Tuna is a salt water fish from the family Scombridae, mostly in the genus Thunnus. Tuna are fast swimmers, and some species are capable of speeds of . Unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red coloration derives from myoglobin, an...
or pods of dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
s that push schooling fish to the surface. 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 Tern
Sooty Tern
The Sooty Tern, Onychoprion fuscatus , is a seabird of the tern family . It is a bird of the tropical oceans, breeding on islands throughout the equatorial zone. Colloquially, it is known as the Wideawake Tern or just wideawake...
s, Spectacled Terns, Brown Noddies
Brown Noddy
The Brown Noddy or Common Noddy is a seabird from the tern family. The largest of the noddies, it can be told from the closely related Black Noddy by its larger size and plumage, which is dark brown rather than black...
and Black Noddies
Black Noddy
The Black Noddy or White-capped Noddy is a seabird from the tern family. It resembles the closely related Brown or Common Noddy , but is smaller with darker plumage, a whiter cap, a longer, straighter beak and shorter tail...
. Studies show that only females (adults and immatures) hunt in this fashion, and only a few individuals account for most of the kills.
Great Frigatebirds will attempt kleptoparasitism
Kleptoparasitism
Kleptoparasitism or cleptoparasitism is a form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food, including stored food...
, chasing other nesting seabirds (boobies
Booby
A booby is a seabird in the genus Sula, part of the Sulidae family. Boobies are closely related to the gannets , which were formerly included in Sula.-Description:...
and tropicbird
Tropicbird
Tropicbirds are a family, Phaethontidae, of tropical pelagic seabirds now classified in their own order Phaethontiformes. Their relationship to other living birds is unclear, and they appear to have no close relatives. There are three species in one genus, Phaethon...
s 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
Masked Booby
The Masked Booby, Sula dactylatra, is a large seabird of the booby family, Sulidae. This species breeds on islands in tropical oceans, 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...
estimated that the frigatebirds could at most obtain 40% of the food they needed, and on average obtained only 5%.
Breeding
Great Frigatebirds are seasonally monogamousMonogamy
Monogamy /Gr. μονός+γάμος - one+marriage/ a form of marriage in which an individual has only one spouse at any one time. In current usage monogamy often refers to having one sexual partner irrespective of marriage or reproduction...
, 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
Red-footed Booby
The Red-footed Booby, Sula sula, is a large seabird of the booby family, Sulidae. As suggested by the name, adults always have red feet, but the colour of the plumage varies. They are powerful and agile fliers, but they are clumsy in takeoffs and landings...
and other species of frigatebirds.
Gular skin
Gular skin , in ornithology, is an area of featherless skin on birds that joins the lower mandible of the beak to the bird's neck....
; 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 their 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
Black Noddy
The Black Noddy or White-capped Noddy is a seabird from the tern family. It resembles the closely related Brown or Common Noddy , but is smaller with darker plumage, a whiter cap, a longer, straighter beak and shorter tail...
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
Guano
Guano is the excrement of seabirds, cave dwelling bats, and seals. Guano manure is an effective fertilizer due to its high levels of phosphorus and nitrogen and also its lack of odor. It was an important source of nitrates for gunpowder...
. 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
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
measuring 68 x 48 mm is laid during each breeding season. 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.
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...
lasts for around 55 days. Great Frigatebird chicks begin calling a few days before hatching and rub their egg tooth
Egg tooth
In some egg-laying animals, the egg tooth is a small, sharp, cranial protuberance used by offspring to break or tear through the egg's surface during hatching...
against the shell. The altricial
Altricial
Altricial, meaning "requiring nourishment", refers to a pattern of growth and development in organisms which are incapable of moving around on their own soon after hatching or being born...
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
Down feather
The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator and padding, used in goods such as jackets, bedding,...
, 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
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
occurs after 4–6 months, the timing dependent on oceanic conditions and food availability. 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
Play (activity)
Play is a term employed in ethology and psychology to describe to a range of voluntary, intrinsically motivated activities normally associated with pleasure and enjoyment...
; 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.