Tag Archives: Acrocephalus sp.

Acrocephalus sp. BMNH 1846.7.29.6

The British Museum of Natural History is apparently housing a reed-warbler specimen that is sister to the Leeward Islands Reed-Warbler (Acrocephalus musae (J. R. Forster)) , a now extinct species that occurred with two subspecies on the islands of Huahine and Ra’iatea in the leeward group of the Society Islands.

However, this single specimen appears not to be identical to either of the two known subspecies and was proposed to be classified as “A. musae subsp. (Leeward Islands), with uncertainty regarding the island and subspecies.” [1]; it might indeed represent another, third subspecies that had been collected from another island within the leeward group.

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References:

[1] Alice Cibois; Jean-Claude Thibault; Eric Pasquet: Molecular and morphological analysis of Pacific reed warbler specimens of dubious origin, including Acrocephalus luscinius astrolabii. Bulletin of the British Ornithologist’s Club 131(1): 32-40. 2011

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edited: 05.07.2023

A reed-warbler from Rurutu?

I found another interesting account that I had overlooked previously in ‘Te Manu: Bulletin de la Société d’Ornithologie de Polynésie. Nr 25. December 1998’.:

“De notre correspondant Yves GENTILLOMME à Rurutu 
Lors du passage de Jean-Yves Meyer sur l’île de Rurutu, Yves Gentillomme lui a signalé avoir entendu le chant facilement reconnaissable d’une fauvette (Acrocephalus sp.). Il n’y a pas de description de fauvettes à Rurutu dans la littérature mais on en trouve une sur l’île voisine de Rimatara: Acrocephalus rimitarae (autrefois considérée comme une sous espèce de Acrocephalus vaughani de Pitcairn) – cf TE MANU n°23. Il s’agit peut être d’un oiseaux en provenance de cette île. Il existe une autre observation de fauvette aux Australes sur l’île de Raivavae. Cette observation ancienne n’a jamais été renouvelée.” [1]

translation:

“From our correspondent Yves GENTILLOMME in Rurutu 
During Jean-Yves Meyer’s visit to Rurutu Island, Yves Gentillomme told him that he heard the easily recognizable song of a warbler (Acrocephalus sp.). There is no description of warblers in Rurutu in the literature but there is one on the neighboring island of Rimatara: Acrocephalus rimitarae (formerly considered as a subspecies of Acrocephalus vaughani from Pitcairn) – see TE MANU n°23. It may be a bird from this island. There is another sighting of a warbler in the Austral Islands on Raivavae Island. This ancient observation has never been repeated.“

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Today the island of Rurutu does not harbor an endemic reed-warbler species but it may well have done so in former times; the neighboring island of Rimatara, however, still is home to an endemic form of reed-warbler, the Rimatara Reed-Warbler (Acrocephalus rimitarae (Murphy and Mathews)), and the bird heard singing on Rurutu in the late 1990s might indeed have been such a bird.

The Rimatara Reed-Warbler may be in the state of expanding its distributional area, or there may just be some stray birds appearing on neigboring islands from time to time. 

There is, however, a very little possibility that there is an endemic Rurutu Reed-Warbler that has survived into the late 1990s.

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References:

[1] Te Manu: Bulletin de la Société d’Ornithologie de Polynésie. Nr 25. December 1998

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edited: 17.03.2020

A reed-warbler from Raivavae?

Hi there!

While reading some stuff in my ‘reed warbler book’ [3] last night, I suddenly remembered that there was a sighting or rather a ‘hearing’ of a reed-warbler on an island where no such reed-warbler was known to exist, and I was quite sure that this was one of the Cook Islands but could not find any mention of it.

But then i found it and it was one of the Austral Islands, namely Raivavae, where a reed warbler was recorded in 1968, and it was apparently indeed not seen but heard only, but it was at least identified as being a reed-warbler.

The island of Raivavae has no surviving endemic land bird species today, but of course did have some of them in the past, among them very, very, veeery likely also a reed-warbler species, and in my humble opinion this appears to have survived until the mid 20th century at least.

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So, I’ve checked my ‘usual suspects’ and found some furter informations, but not really that much, unfortunately.

Te Manu: Bulletin de la Société d’Ornithologie de Polynésie. Nr 24. September 1998:

“Une espèce non identifiée d’Acrocephalus a été notée à Raivavae en 1968 mais n’a pas été retrouvé en 1990 (Seitre et Seitre 1991) et pouvait donc être un oiseau erratique.“

translation:

“An unidentified species of Acrocephalus was recorded at Raivavae in 1968 but was not found in 1990 (Seitre and Seitre 1991) and could therefore be an erratic bird.“

This record obviously is mentioned by D. T. Holyoak and J.-C. Thibault in 1984 [1] but I was not able to read it myself, however, I’m rather convinced that the ‘erratic bird’ more likely is meant to be what in German is called a “Irrgast”, a migratory bird that appeared on the island inadvertently while flying from one point to another.

But are there migratory reed warblers flying over the Austral Islands? No, because if they fly from north to south or back, they just do not cross the middle of the Pacific Ocean since the migratory reed-warbler species only inhabit the continents of the ‘Old World’ and those inhabiting the Polynesian islands do not migrate, as far as I know.

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In chapter 7 of David W. Steadman’s ‘Extinction and Biogeography of Tropical Pacific birds’ from 2006 [2] it is mentioned as Acrocephalus vaughani and as a ‘M, modern record’ from Raivavae. How could I actually miss that until today?

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I personally are rather sure that this single record from the island of Raivavae is indeed the last record of a former existing population of native, probably endemic, Raivavae Reed-Warblers which now join the ever-growing list of extinct taxa. 

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Here is a little update, in the meantime I was able to finde the original work by D. T. Holyoak and J.-C. Thibault from 1984.:

“A. v. sous-espèce ? 

Raevavae: des fauvettes furent entendues par Lacan (J.-L. Mougin, comm. pers.) en mai 1968.” [1]

translation:

“A. v. subspecies? 

Raevavae: warblers were heard by Lacan (J.-L. Mougin, pers. comm.) in May 1968.“

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References:

[1] D. T. Holyoak; J.-C. Thibault: Contribution à l’étude des oiseaux de Polynésie orientale. Mémoires du Muséum national d’histoire naturelle 127(1): 1-209. 1984
[2] David W. Steadman: Extinction and Biogeography of Tropical Pacific Birds. University of Chicago Press 2006
[3] David Pearson; Peter Kennerly: Reed and Bush Warblers. Christopher Helm 2009

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edited: 10.03.2020