Rarotonga monarch
| Rarotonga Monarch | |
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| Species: | P. dimidiata
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| Binomial name | |
| Pomarea dimidiata (Hartlaub & Finsch, 1871)
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The Rarotonga Monarch (Pomarea dimidiata), also known as the Kakerori, is a species of bird in the monarch flycatcher family Monarchidae. It is endemic to the Cook Islands.
It is a most unusual bird in a number of ways, being the only bird known to undergo sequential changes in plumage as it grows [2] from orange to orange-grey to pure grey when maturity is reached after four years. Owing to its tropical oceanic island location, the kakerori is exceptionally long-lived for a bird with a mass of 22 grams (0.8 oz),[2] having an adult survival of between 85 and 89 percent, a life expectancy of seven to nine years, and a maximum lifespan from a single banding scheme started in the middle 1980s of around 24 years. These figures are comparable to large Australian passerines like the Superb Lyrebird or Satin Bowerbird[3] and more than ten times the life expectancies of similar sized Holarctic songbirds. Such extraordinary longevity may explain the evolution of helpers at the nest in a family where this feature is otherwise completely absent[4]: males can breed at one year, but do not do so in practice until they are four.[5]
Since the introduction of the black rat and feral cat adult mortality has more than doubled, a change sufficient to reduce what was previously a highly numerous bird[5] to one of the most endangered birds in the world by the middle 1980s, when the kakerori was listed as one of the highest conservation priorities among all Pacific Island birds.[6] The removal of rats has made breeding more successful: around two thirds of pairs assisted by a few helpers can now rear both of the normal clutch of two eggs, whereas in the 1980s breeding attempts had a success rate as low as eleven percent.[5] Despite the growth in population, it is still known that a major tropical cyclone could destroy this growth extremely swiftly, so that conservation work is still very important.
References
- ^ Template:IUCN
- ^ a b “Conservation of kakerori (Pomarea dimidiata) in the Cook Islands in 2004-05”
- ^ See Australian Bird and Bat Banding Scheme
- ^ Distribution of known and inferred modes of parental care in families and subfamilies of birds
- ^ a b c “Breeding biology of the kakerori (Pomarea dimidiata) on Rarotonga, Cook Islands”
- ^ [1]