Frigatebirds are also referred to as “frigatebird,” “frigate-bird,” “frigate,” or “frigate-petrel.”
These birds are from a family of seabirds called Fregatidae, located throughout all tropical and subtropical oceans.
These five extant species are classified in a single genus, Fregata. The frigatebirds are capable of soaring for weeks on wind currents.
They spend most of the day in flight, foraging for food and sleeping on trees or cliffs at night.
Frigatebirds are called kleptoparasites as they occasionally steal other seabirds for food and are also known to snatch seabird chicks from their nest.
Three of these birds’ five extant species are widely distributed.
They include the magnificent, great, and lesser frigatebirds.
The remaining two species, “Christmas Island and Ascension Island frigatebirds” are endangered.
As a result of their conservation status, their breeding habitats are confined to one small island each.
The most ancient fossils can be dated to the early Eocene, around 50 million years ago. A frigatebird can sleep during a flight.
Their lifespan remains uncertain, but one bird on the Tern island was older than 37 years, while another was said to be up to 44 years.
So, the safe claim is that the frigates have a long life span.
Scientific classification
| Kingdom | Animalia |
| Phylum | Chordata |
| Class | Aves |
| Order | Suliformes |
| Family | Fregatidae |
| Genus | Fregata |
| Scientific name | Fregatidae |
The species of the frigatebird include:
| Fregata magnificens | Magnificent frigatebird |
| Fregata aquila | Ascension frigatebird |
| Fregata andrewsi | Christmas frigatebird |
| Fregata minor | Great frigatebird |
| Fregata ariel | Lesser frigatebird |
Description
Frigatebirds are slender birds with primarily black plumage. It has five species that are very similar in physical appearance to each other.
The biggest species is the magnificent frigatebird, with a body length of about 45 inches. Three species, excluding the lesser frigatebird, are nearly equal to the magnificent frigatebird in terms of body size. The lesser frigatebird is the smallest, with a body length of about 27 inches.
Frigatebirds are conspicuously sexually dimorphic, with the females being considerably larger and weighing up to 25% heavier than the males.
They commonly have white marks on their underparts with short necks and lengthy, slender, hooked bills. Their wings are narrow and long, and the male’s wingspan measures up to 7.5 feet from the taper to the points.
Their wings comprise 11 primary feathers for flight, and the tenth feather is the longest, while the eleventh isn’t fully developed. They also have 23 secondary feathers for flight. They have deeply forked tails, which aren’t conspicuous unless the tail is fanned.
Their wings and tails form an apparent “W” shape during flight. Their faces and legs are fully covered with feathers, and their feet are weak and short.
The frigatebirds’ bones are very light and only comprise 5% of their body weight. They have a strong pectoral girdle with well-built pectoral muscles.
These muscles and feathers comprise about 50% of the total body weight. The males have a red-colored throat pouch that is inflatable.
This pouch is also called a gular pouch, and the males use it to attract the females during the breeding season. The gular sac or pouch is the frigatebird’s most distinctive feature.
Habitat
Their preferred habitats are tropical and subtropical regions.
Diet
They mainly feed on small fish, such as the flying fish, chased to the surface by predators such as tuna and dolphins.
They also feed on cephalopods, particularly squid. Frigatebirds also prey directly on eggs and the offspring of other seabirds such as boobies, petrels, shearwaters, and terns, in particular the sooty tern.
In contrast to other seabirds, frigatebirds drink fresh water when they approach it by swooping down and gulping it with their bills.
Habits
The frigates have the largest ratio of wing area to body weight when compared to any bird. They spend most of their time in the air. Due to the build of their wings, they can soar for long periods, only occasionally flapping their wings.
A great frigate was once monitored by a satellite in the Indian Ocean, soaring for about two months. In freezing conditions, they can fly at heights above 4,000 meters.
They can spend the entire night in the air, taking their nap, but they always return to an island when they want to breed and roost.
A frigate can stay on the air for about 12 days during their hunt or foraging for food. They are highly skilled in using their forked tails to navigate their flight and make powerful, deep beats with their wings.
Frigatebirds prefer to soar because they are not suited to flight by sustainable wing flapping. These birds bathe by flying low and hitting the water’s surface before they scratch and preen later. They are terrible swimmers and cannot easily fly from the sea.
Even though these birds have dark plumage in a tropical climate, they have figured out ways not to overheat. They use this, especially when exposed to full sunlight on the nest.
They shake their feathers to lift them away from the skin to boost air circulation. They also expand and upturn their wings to expose the hot undersurface to the air. This triggers the loss of heat by evaporation and convection.
Reproduction
Frigates typically mate on remote, oceanic islands and usually breed in colonies of up to 5,000 birds. These colonies have a nesting group of 10 – 30 birds, with rare cases of these groups numbering up to 100.
Mating can occur at any time of the year, but it mostly occurs during the availability of abundant food or dry season.
Frigates are known to have the most dazzling displays among seabirds. They exhibit this display to female frigates flying overhead by pointing their bill upwards, inflating their gular sacs, and vibrating their extended wings. They create a drumming sound by vibrating their bills together and emitting a whistling call.
The female frigate descends from flight to meet with the male of her choice and lets him take her bill in his. The mating pair engages in shaking heads together.
After mating, the male usually gathers the sticks, and the female makes the loosely woven nest. The nest is eventually cemented or covered with guano.
These birds prefer nesting in trees or bushes but opt for grounds when vegetation isn’t unavailable. They lay just a single egg that could weigh up to about 7% of the mother’s body weight. Both parents take turns incubating the egg for a period ranging between 41 and 55 days.
The frigate chicks are naked when hatched and develop a white down. They are always protected by their parents for the first six weeks and feed on the nest for about six months.
Both the father and mother take turns to provide for the first three months, and then the father holds back, leaving the mother to continue the chore.
The chicks feed from their parents by putting their heads in their parents’ throats and feeding on the partly regurgitated food. Unlike other animals, even birds, it usually takes the frigates long to rear a chick. Frigates typically breed every year.
Conservation status
Aside from the declining numbers of two species of the frigates, the great and lesser frigatebird, the other three species of frigates are classified as “Least Concern.”
