A new Leaf-warbler from Rote Island, Indonesia

23 Oct 2018 - 11:07 -- José Luis Copete

A joint research team from the National University of Singapore (NUS) and Indonesian Institute of Science has described an unusual new songbird species. The bird was named the Rote Leaf-warbler Phylloscopus rotiensis after the island of Rote where it is found. The discovery was published in the journal Nature Scientific Reports on 23 October 2018.

Rote Island is a dry monsoon island with an area of 1,200 square kilometres in eastern Indonesia. It is around 12 kilometres off the coast of Timor, and about 500 kilometres northwest of Australia. The island has recently been the site of discovery of another new bird species to science, the Rote Myzomela (Myzomela irianawidodoae), which was published in the journal Treubia on 31 December 2017.

The presence of a leaf-warbler of unknown identity on Rote was first noted in December 2004 by Dr Colin Trainor from Charles Darwin University, Australia. In July 2009, Mr Philippe Verbelen and Ms Veerle Dossche, two Belgian birdwatchers, made detailed observations and obtained a series of photographs of the bird.

“Alarm bells went off when we realised how strikingly different the bill shape and the coloration of the Rote bird was compared to all other leaf-warblers,” remembered Mr Verbelen.

“The new species is part of a large group of Asian warblers but is unique among them in its unusually long bill,” said Dr Nathaniel Ng, who was involved in the description of the bird during his PhD candidature at the Department of Biological Sciences at the NUS Faculty of Science.

He added, “This odd bill shape is likely an adaptation to Rote’s dry landscapes, given that most other Asian leaf-warblers live in humid forest.”

The scientific description was partly aided by comparisons using genome-wide data collected through Next-Generation Sequencing. “This may well be the first time – to the best of our knowledge – that a new bird species has been described partly on the basis of genome-wide DNA data,” added Miss Elize Ng, a researcher with the Avian Evolution Lab (AEL) under the NUS Department of Biological Sciences.

“This work would not have been possible without the partnership with the Indonesian Institute of Science, and in particular Dr Dewi Prawiradilaga,”said Assistant Professor Frank Rheindt, the leader of the study and Head of the AEL under the NUS Department of Biological Sciences.

Worldwide only 5-10 new bird species are described each year but incredibly this is the second novel species description from Rote in 2018, highlighting the island’s global conservation value. Rote's natural landscapes are under grave threat, with a burgeoning human population exerting ever-increasing pressures on its monsoon woodland and savannah, prompting the proposal that the bird be formally classified by the International Union for the Conservation of Nature (IUCN) as Vulnerable.

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Leaf-warblers (Phylloscopidae)

Formerly included in a broad Sylviidae. Recent review#R indicates that previous internal arrangement, with all taxa of present family split between Seicercus and Phylloscopus, was paraphyletic. As a result some authors have split Phylloscopus into several smaller genera, with some movement of taxa from Phylloscopus to Seicercus, but accuracy of this debatable on present knowledge. One of these versions#R involves groups containing species as listed below: Rhadina (species 1–3); Abrornis (species 4–13); Phylloscopus (species 14–28); and Seicercus (species 29–78). Another version#R divides family into nine genera. More cautious alternative involves merging Seicercus into Phylloscopus; adopted herein, pending results of a comprehensive study currently in progress#R.