Guadalcanal Thicketbird Cincloramphus turipavae Scientific name definitions

Like other Melanesian members of the genus, the Guadalcanal Thicketbird of Guadalcanal, Solomon Islands, is an extremely elusive bird of the understory of dense montane forest. It remains very poorly known. If encountered, it is usually heard only. Guadalcanal Thicketbird was formerly considered conspecific with Santo Thicketbird (Cincloramphus whitneyi) of Espiritu Santo, Vanuatu, but these highly disjunct taxa from different island groups differ morphologically and are best treated as two distinct species.

17–19 cm; 36 g. A relatively long-tailed, medium-sized warbler, with rich buff-brown supercilium, dark olive- or sepia-brown upperparts, darkest on crown and blackish on graduated and point-tipped tail; iris dark brown; bill blackish; legs and feet fuscous-brown. Juvenile undescribed.

No similar species on the island of Guadalcanal. Differs from Santo Thicketbird (Cincloramphus whitneyi) of Espiritu Santo, Vanuatu, in its notably darker, browner upperparts, throat, breast, and flanks, and blacker tail; may also have longer tail spines but confirmation is needed. Originally described as apparently having a more inflated nasal operculum than in the Santo Thicketbird (1 Cain, A. J., and I. C. J. Galbraith (1955). Five new subspecies from the mountains of Guadalcanal (British Solomon Islands). Bulletin of the British Ornithologists’ Club 75:90-93. Close ). Resembles Bougainville Thicketbird (Cincloramphus llaneae), but Guadalcanal Thicketbird has slightly broader facial masks, lacks brown scalloping on lesser wing coverts, has more rufous underparts, and has a browner tail with more developed terminal tail spines.

The bare parts of the type specimen were as follows: iris dark brown; bill blackish with whitish streaks on mandible; gape pale dull yellow; feet fuscous brown (1 Cain, A. J., and I. C. J. Galbraith (1955). Five new subspecies from the mountains of Guadalcanal (British Solomon Islands). Bulletin of the British Ornithologists’ Club 75:90-93. Close ).

Linear Measurements

Type specimen, male, in mm (1 Cain, A. J., and I. C. J. Galbraith (1955). Five new subspecies from the mountains of Guadalcanal (British Solomon Islands). Bulletin of the British Ornithologists’ Club 75:90-93. Close ):

• bill depth 5.0
• wing 65.5
• tail 76.5+
• tarsus 27.5
• middle toe with claw 24.0
• hind toe with claw 20.5
• distance between first and longest primary 21.0
• distance between longest primary and secondary 5.0
• distance between longest and shortest tail feathers 36.5

Mass

Type specimen, male (1 Cain, A. J., and I. C. J. Galbraith (1955). Five new subspecies from the mountains of Guadalcanal (British Solomon Islands). Bulletin of the British Ornithologists’ Club 75:90-93. Close ): 36.0 g.

Guadalcanal Thicketbird (Cincloramphus turipavae) was long considered conspecific with Santo Thicketbird (Cincloramphus whitneyi), but here the two are split on the basis of morphological differences, biogeographic implausibility of a montane, poorly dispersive species being shared exclusively between Guadalcanal (southern Solomons) and Santo (Vanuatu), and the lack of a published rationale for the original lump while other Melanesian Cincloramphus have been split (2 Dutson, G. (2011). Birds of Melanesia: The Bismarcks, Solomons, Vanuatu and New Caledonia. Christopher Helm, London, UK. Close , 3 del Hoyo, J., and N. J. Collar (2016). HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions, Barcelona, Spain. Close ). Together, Cincloramphus turipavae and Cincloramphus whitneyihave also been considered conspecific with Bismarck Thicketbird (Cincloramphus grosvenori) and Bougainville Thicketbird (Cincloramphus llaneae) (as here, following long-standing treatment; 1 Cain, A. J., and I. C. J. Galbraith (1955). Five new subspecies from the mountains of Guadalcanal (British Solomon Islands). Bulletin of the British Ornithologists’ Club 75:90-93. Close , 4 Diamond, J. M., and A. G. Marshall (1976). Origin of the New Hebridean avifauna. Emu 76(4):187–200. Close , 5 Dickinson, E. C., and L. Christidis, Editors (2014). The Howard and Moore Complete Checklist of the Birds of the World. Volume 2. 4th edition. Aves Press, Eastbourne, UK. Close ). In their assessment of the taxa, del Hoyo and Collar (3 del Hoyo, J., and N. J. Collar (2016). HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions, Barcelona, Spain. Close ), using the Tobias et al. (6 Tobias, J. A., N. Seddon, C. N. Spottiswoode, J. D. Pilgrim, L. D. C. Fishpool, and N. J. Collar (2010). Quantitative criteria for species delimitation. Ibis 152(4):724–746. Close ) criteria, from which the numbers in brackets are derived, found that Cincloramphus turipavae differs from both Cincloramphus grosvenori and Cincloramphus whitneyi by its longer tail with notably elongate spine-tips [clarification needed; 3]; and further from Cincloramphus grosvenori by its much weaker facial mask [2]; and sepia-tawny versus ochraceous-buff throat to breast [1]; and from Cincloramphus whitneyi by its slightly weaker mask [1], broad dark brown breast sides to lower flanks [2]; and darker, less rufous-tinged upperparts [1].

Cincloramphus turipavae has not been included in any molecular phylogeny, so its relationships are not resolved. It is presumably closely related to Cincloramphus whitneyi, Cincloramphus grosvenori, and Cincloramphus llaneae, as all had been considered conspecific at one point (5 Dickinson, E. C., and L. Christidis, Editors (2014). The Howard and Moore Complete Checklist of the Birds of the World. Volume 2. 4th edition. Aves Press, Eastbourne, UK. Close , 3 del Hoyo, J., and N. J. Collar (2016). HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions, Barcelona, Spain. Close ). In a molecular phylogeny of some of these taxa, Cincloramphus whitneyi was found to be sister to Long-legged Thicketbird (Cincloramphus rufus) and New Caledonian Grassbird (Cincloramphus mariae), while Cincloramphus grosvenori was found to be sister to Rusty Thicketbird (Cincloramphus rubiginosus) (7 Alström, P., A. Cibois, M. Irestedt, D. Zuccon, M. Gelang, J. Fjeldså, M. J. Andersen, R. G. Moyle, E. Pasquet, and U. Olsson (2018). Comprehensive molecular phylogeny of the grassbirds and allies (Locustellidae) reveals extensive non-monophyly of traditional genera, and a proposal for new classification. Molecular Phylogenetics and Evolution 127:367–375. Close ). Further work is needed to clarify the relationships of Cincloramphus turipavae and other members of Cincloramphus.

Guadalcanal (Turipava), in southeastern Solomon Islands.

Occurs in upper montane forest, with both dense bamboo undergrowth and sparse understory, at 1200–1550 m.

Resident, so far as is known.

Diet unknown. Observed alone. Keeps very much to ground under dense growth of ferns and other vegetation, often with slightly cocked and spread tail, and only flies short distances; extremely difficult to observe.

Unknown; probably gives clear whistles like other Cincloramphus in the region.

Nothing known; a male collected in mid August was not in breeding condition.

Not globally threatened. Currently considered Near Threatened. Restricted-range taxon: present in Solomon Group Endemic Bird Area, where it is believed to be present in no more than 1000 km². Because of its extremely shy and retiring habits and also the nature of its habitat (wet montane forest), status difficult to assess with accuracy, but population estimated at 1000–2000 individuals and is believed to be stable. Known from only three observations at the type locality, from Turipava above Honiara, on Guadalcanal. Nevertheless, montane forest remains remarkably intact. Introduced mammalian predators, notably feral cats, are the most likely threats for these terrestrial birds.

Guadalcanal Thicketbird is extremely poorly known, so much so that even photographs and sound recordings thus far seem to be unavailable. Almost any information on their biology would be new to science. Further study on their relationships is needed to clarify whether they are indeed best considered separate species from other thicketbirds, as seems likely given the fact that no other congener is distributed on more than one island group. The question of differences in development of tail spines between related taxa requires clarification.