Pacific robin

Pacific robin[1]
P. p. kleinschmidti, Viti Levu, Fiji
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Petroicidae
Genus: Petroica
Species: P. pusilla
Binomial name
Petroica pusilla
(Peale, 1848)
Synonyms

Petroica multicolor

The Pacific robin (Petroica pusilla), is a red-breasted Australasian robin in the passerine bird genus Petroica found in Melanesia and Polynesia. It is similar in plumage to the scarlet robin of Australia, and until recently the two were considered conspecific until split in 1999 by Schodde and Mason.[3] 14 subspecies of Pacific robin are currently recognised,[4] and these subspecies display considerable variation in plumage, foraging preferences and habitat. The Norfolk robin was previously considered a subspecies of the Pacific robin, but is now considered a distinct species.[5]

Description

The Pacific robin is a small passerine, 11.5–13.5 cm long and weighing 9–11 g.[4] Over much of its range it is the smallest species of bird. The plumage of the males and females is dimorphic, and the extent of this varies depending on the subspecies. The male of the nominate race has a black head with a white forehead, a black back and tail, and the wings are also black with a white bar. The breast and belly are red, and the lower belly and rump are white. The female lacks the white forehead and the white bar on the wing; and the black plumage of the male is replaced by dark brown feathers instead. The breast is a duller red than the male and has more brown on the sides, and the white on the rump also smaller. Both sexes have black legs and bills. Amongst the subspecies, some males have more female-like plumage, for example P. m. femenina of central Vanuatu; in others the female more closely resembles the male. The males of P. m. polymorpha of Makira in the Solomon Islands have two different plumage morphs, including one with no white on the forehead but an all rufous-brown head. For a complete list of the differences in subspecies plumages see below.

Distribution and habitat

Male Pacific robin, central Viti Levu, Fiji

The Pacific robin inhabits the islands of the south western Pacific. It ranges from Bougainville in Papua New Guinea through the Solomon Islands and Vanuatu. (although the species is absent from New Caledonia) and eastwards through Fiji into Samoa.[4] Across its range the species is resident, although there may be some small localised movements of birds in the non-breeding seasons. A fossil found on the islands of Ha'apai in Tonga show that the species once occurred in the group but is now extinct there.[6]

Diet and feeding

Insects, spiders and pseudoscorpions make up the majority of the diet of Pacific robins. They generally feed in the lower sections of the forest, although they will ascend to the forest canopy occasionally. They will join with mixed-species feeding flocks in order to forage. Prey is obtained by aerial flycatching, gleaning, sallying and pouncing, with different populations favouring different methods.

Breeding

The Pacific robin is a seasonal breeder, although the timing of the breeding season varies across its range.[4] Information on the timing of the season is patchy or absent in many islands. On Norfolk Island the breeding season is from September to December, and in Vanuatu the season is from October to January. Parents with young have been seen in mid August in the Solomon Islands and in June through to September in Samoa. The species builds a compact nest which is a cup of plant fibres and spider webs.[7] The outside of the nest is decorated with moss and lichen, and is therefore easily overlooked. The nest is usually set into a fork or stump on a tree branch, or on a horizontal branch.

Around two to four eggs are laid in each clutch, with two being the typical clutch size in Norfolk Island, and two to three being typical in Fiji. The eggs are dull grey or greenish, and are incubated by the female. The nests of Pacific robins are parastised by fan-tailed cuckoos where the two species co-occur.

Threats and conservation

The Pacific robin is not considered globally threatened.[2] Individual subspecies may be threatened by local habitat loss, and the nominate race from Norfolk Island is considered vulnerable due to habitat loss and introduced species.[8]

Taxonomy

The Pacific robin was originally described by German naturalist Johann Friedrich Gmelin in 1789, from a collection in Norfolk Island. It was considered conspecific with the scarlet robin of Australia, and until split in 1999 by Schodde and Mason.[3] It forms a species group along with the scarlet robin and the tomtit of New Zealand.[4] It was further split from the Norfolk robin in 2015.[5] Since the Norfolk birds were discovered first, the Norfolk robin presumed the specific name multicolor, with the Pacific group talking the next earliest name of pusilla. The bird follows then to be described by Titian Peale in 1848.

It is one of five red- or pink-breasted species of robin in the genus Petroica; they are colloquially known as "red robins". Although named after the European robin, is not closely related to it or the American robin. Along with the other Australian robins, it was classified for many years as a member of the old world flycatcher family Muscicapidae,[9] before being placed in the whistler family Pachycephalidae.[10] The robins were also placed in their own family Petroicidae, or Eopsaltridae.[10]

Sibley and Alquist's DNA-DNA hybridisation studies placed the robins in a Corvida parvorder comprising many tropical and Australian passerines including pardalotes, fairy-wrens and honeyeaters as well as crows.[11] However, subsequent molecular research (and current consensus) places the robins as a very early offshoot of the Passerida ("advanced" songbirds).[12]

Subspecies

Subspecies of Pacific robin
Trinomial name
and author 		Range Description and notes
P. p. ambrynensis (Sharpe, 1900) Espiritu Santo, Aoba, Ambryn, Paama, Lopevi and Tongoa; north and central Vanuatu & Banks Islands Like nominate but less white in the wings, female has orange red breast. Pronounced sexual dimorphism.
P. p. similis (G.R. Gray, 1860) Tanna and Aneityum; South Vanuatu As P. m. ambrynensis but male has even duller sooty black plumage.
P. p. femenina (Mayr, 1934) Efate and Emao; central Vanuatu Male looks more like female, brown upperparts and brown plumage encroaching the red breast. Female lighter than male with cinnamon tinge and off white throat.
P. p. soror (Mayr, 1934) Vanua Lava; Banks Islands As P. m. femenina but darker upperparts and more scarlet on throat.
P. p. cognata (Mayr, 1938) Erromango; south central Vanuatu Similar to P. m. soror, but upperparts greyish, and with white in the tail.
P. p. polymorpha (Mayr, 1934) Marika; Solomon Islands The males are dimorphc, some with black heads and some with rufous, lack the white forehead. Female resembles the rufous headed male but duller.
P. p. septentrionalis (Mayr, 1934) Bougainville; Papua New Guinea Male identical to black headed morph of P. m. polymorpha, female has more rufous upperparts and some white in wing.
P. p. kulambangrae (Mayr, 1934) Kolombangara; west Solomon Islands Male as P. m. septentrionalis, female has reddish upperparts and deeper red breast.
P. p. dennisi (Cain & I.C.J Galbraith, 1955) Guadalcanal; south Solomon Islands Male as black-morph P. m. polymorpha, female has olive-brown crown and blacker back and wings.
P. p. pusilla (Peale, 1848) Savai'i and Upolu; Samoa Nominate; Male has sooty black upperparts and head, more white on wing, smaller white patch on forehead.
P. p. kleinschmidti (Finsch, 1876) Viti Levu and Vanua Levu; Fiji As P. m. pusilla but male has larger white forehead patch and darker upperparts, female much greyer upperparts, broad wingbar.
P. p. taveunensis (Holyoak, 1979) Taveuni; Fiji Like P. m. kleinschmidti but male has deeper red on breast and female has brown upperparts.
P. p. becki (Mayr, 1934) Kadavu; south Fiji As P. m. kleinschmidti but male and female have lighter upperparts.

References

  1. ↑ Gill, Frank; Donsker, David, eds. (2010). "Vireos, Crows & Allies". IOC World Bird Names (version 2.4). Retrieved 17 March 2010.
  2. 1 2 BirdLife International (2012). "Petroica multicolor". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
  3. 1 2 Schodde R, Mason IJ (1999). The Directory of Australian Birds : Passerines. A Taxonomic and Zoogeographic Atlas of the Biodiversity of Birds in Australia and its Territories. Collingwood, Australia: CSIRO Publishing. pp. x 851 pp. ISBN 0-643-06456-7.
  4. 1 2 3 4 5 Boles, W (2007) "Family Petroicidae (Australasian Robins)" in del Hoyo, J.; Elliot, A. & Christie D. (editors). (2007). Handbook of the Birds of the World. Volume 12: Picathartes to Tits and Chickadees. Lynx Edicions. ISBN 978-84-96553-42-2 P. 483
  5. 1 2 Kearns, A. M. et al. (2016) Norfolk Island Robins are a distinct endangered species: ancient DNA unlocks surprising relationships and phenotypic discordance within the Australo-Pacific Robins. Conservation Genetics 17, 321–335.
  6. ↑ Steadman D, (2006). Extinction and Biogeography in Tropical Pacific Birds, University of Chicago Press. ISBN 978-0-226-77142-7
  7. ↑ Bregulla, Heinrich L. (1992) Birds of Vanuatu, Anthony Nelson, Oswestry, England. ISBN 0-904614-34-4 pp.226-227
  8. ↑ Commonwealth of Australia. (2005). National Recovery Plan for the Norfolk Island Scarlet Robin Petroica multicolor multicolor and the Norfolk Island Golden Whistler Pachycephala pectoralis xanthoprocta. Department of the Environment and Heritage, Canberra. ISBN 0-642-55166-9
  9. ↑ Boles, p. xv
  10. 1 2 Boles, p. 35
  11. ↑ Sibley CG, Ahlquist JE (1990). Phylogeny and Classification of Birds: A Study in Molecular Evolution. New Haven, CT: Yale University Press. pp. 603, 610–27. ISBN 0-300-04085-7.
  12. ↑ Barker, F. Keith; Cibois, Alice; Schikler, Peter A.; Feinstein, Julie & Cracraft, Joel (2004). "Phylogeny and diversification of the largest avian radiation." (PDF). PNAS. 101 (30): 11040–45. doi:10.1073/pnas.0401892101. PMC 503738Freely accessible. PMID 15263073. Retrieved 2008-08-14.

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