The Rarotonga monarch (''Pomarea dimidiata''), also known as the Rarotonga flycatcher or ''kakerori'', is a species of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

in the monarch flycatcher family

Monarchidae The monarchs (family Monarchidae) comprise a family of over 100 passerine birds which includes shrikebills, paradise flycatchers, and magpie-larks. Monarchids are small insectivorous songbirds with long tails. They inhabit forest or woodland a ...

. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the

Cook Islands ) , image_map = Cook Islands on the globe (small islands magnified) (Polynesia centered).svg , capital = Avarua , coordinates = , largest_city = Avarua , official_languages = , lan ...

Taxonomy and systematics

The Rarotonga monarch was originally described in the genus ''

Monarcha ''Monarcha'' is a genus of bird in the family Monarchidae. They are found in Australia and Melanesia. Taxonomy and systematics The genus ''Monarcha'' was introduced by naturalists Nicholas Vigors and Thomas Horsfield in 1827 with the black-fac ...

''. Alternate names include Cook Island flycatcher, Cook Islands monarch, and Rarotonga monarch-flycatcher.

Description

The Rarotonga monarch is a most unusual bird in a number of ways, including being the only bird known to undergo sequential changes in plumage as it grows. The initial plumage of orange to orange-grey changes to pure grey when maturity is reached after four years.“Conservation of kakerori (''Pomarea dimidiata'') in the Cook Islands in 2004-05”
/ref>

Behaviour and ecology

Owing to its tropical oceanic island location, the Rarotonga monarch is exceptionally long-lived for a bird with a mass of only , having an adult survival of between 85 and 89 percent, a life expectancy of seven to nine years, and a maximum lifespan of around 24 years. These figures are comparable to large Australian passerines like the

superb lyrebird The superb lyrebird (''Menura novaehollandiae'') is an Australian songbird, one of two species from the family Menuridae. It is one of the world's largest songbirds, and is renowned for its elaborate tail and courtship displays, and its excell ...

satin bowerbird The satin bowerbird (''Ptilonorhynchus violaceus'') is a bowerbird endemic to eastern Australia. A rare natural hybrid (biology), intergeneric hybrid between the satin bowerbird and the regent bowerbird is known as Rawnsley's bowerbird. Descrip ...

and more than ten times the life expectancies of similar sized

Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical region ...

songbirds.

Breeding

The extraordinary longevity of these birds may explain the evolution of

helpers at the nest Helpers at the nest is a term used in behavioural ecology and evolutionary biology to describe a social structure in which juveniles and sexually mature adolescents of either one or both sexes remain in association with their parents and help the ...

in a family where this feature is otherwise completely absent. Males can breed at one year, but do not do so in practice until they are four years old.“Breeding biology of the kakerori (''Pomarea dimidiata'') on Rarotonga, Cook Islands”
/ref>

Threats

Since the introduction of the

black rat The black rat (''Rattus rattus''), also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae. It likely originated in the Indian subcontinent, but is n ...

and

feral cat A feral cat or a stray cat is an unowned domestic cat (''Felis catus'') that lives outdoors and avoids human contact: it does not allow itself to be handled or touched, and usually remains hidden from humans. Feral cats may breed over dozens ...

, adult mortality has more than doubled; a change sufficient to reduce what was previously a highly numerous bird to one of the most endangered birds in the world by the middle 1980s, when the Rarotonga monarch was listed as one of the highest conservation priorities among all Pacific Island birds. The annual pre-breeding removal of rats (starting in the late 1980s) from its principal breeding area on the south coast of Rarotonga (at the Takitumu Conservation Area) by staff and volunteers has made breeding significantly more successful: around two thirds of pairs assisted by a few helpers can now rear the normal clutch of two eggs, whereas in the 1980s breeding attempts had a success rate as low as eleven percent. Despite the growth in population, a major

tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...

could destroy this population growth with extreme swiftness, so that conservation work is still very important.

Status

The Rarotonga monarch was limited to

Rarotonga Rarotonga is the largest and most populous of the Cook Islands. The island is volcanic, with an area of , and is home to almost 75% of the country's population, with 13,007 of a total population of 17,434. The Cook Islands' Parliament buildings a ...

until a second population was established on

Atiu Island Atiu, also known as Enuamanu (meaning ''land of the birds''), is an island of the Cook Islands archipelago, lying in the central-southern Pacific Ocean. Part of the Nga-pu-Toru, it is northeast of Rarotonga. The island's population has dropped by ...

in 2001. In the 1990s its population was estimated at fewer than 30 birds in the wild. In 2022 the population was assessed at over 700 birds.

References

External links

BirdLife Species Factsheet.
{{Taxonbar, from=Q2224937

Rarotonga monarch The Rarotonga monarch (''Pomarea dimidiata''), also known as the Rarotonga flycatcher or ''kakerori'', is a species of bird in the monarch flycatcher family Monarchidae. It is endemic to the Cook Islands. Taxonomy and systematics The Rarotonga m ...

Birds of the Cook Islands Rarotonga

Taxonomy articles created by Polbot