New avian species discovered in little-explored islands of Wallacea

NUS researchers have discovered five bird species and five subspecies new to science from a region near Sulawesi, Indonesia.

Birds are the best known class of animals, and since 1999, only five or six new species have been described each year on average. A research team led by Prof Frank Rheindt from the Department of Biological Sciences, NUS, has discovered five bird species and five subspecies new to science in three small island groups off Sulawesi, Indonesia. The islands are situated in Indonesia’s Wallacea region, an archipelago at the interface between the Oriental and Australian biogeographical realms, named after Sir Alfred Wallace, who was the most famous historical collector exploring the area.

Sea depth is an important and long-neglected factor in determining the distinctness of an island’s terrestrial communities. The Earth undergoes periods of glacial-interglacial cycles, leading to the formation of land bridges between shallow islands during ice ages, allowing fauna of the different islands to interbreed. Deep sea islands, which have always been isolated, and high elevation islands are more likely to harbour endemism due to absence of land connections even during glacial cycles.

Guided by this knowledge, Prof Rheindt and his team focused their research efforts on the islands of Taliabu and Peleng, which are located off the north-eastern coast of Sulawesi, as bathymetric data (information relating to the underwater terrain) indicate the presence of deep sea between these islands and Sulawesi.

The research team undertook extensive fieldwork in the remote islands for six weeks, from November 2013 to January 2014, and collected 10 new, long-overlooked avian forms

By integrating genomic and phenotypic research methodologies, the team successfully described five new songbird species and five new subspecies:

• On Taliabu island, they found three new species: the Taliabu Grasshopper-Warbler, the Taliabu Myzomela and the Taliabu Leaf-Warbler; and three subspecies: the Taliabu Snowy-browed Flycatcher, Taliabu Island Thrush and Sula Mountain Leaftoiler.

• On Peleng island, they found two new species: the Peleng Fantail and the Peleng Leaf-Warbler; and a new subspecies: the Banggai Mountain Leaftoiler.

• On Togian island, they found a new subspecies: the Togian Jungle-Flycatcher.

Prof Rheindt said, “Going forward, the use of earth-history and bathymetric information could also be applied to other terrestrial organisms and regions beyond the Indonesian Archipelago to identify promising islands that potentially harbour new taxa to be uncovered.”

Visual showing the three new species found on Taliabu island (from left), the Taliabu Grasshopper-Warbler, the Taliabu Myzomela and the Taliabu Leaf-Warbler. [Credit: (left) Robert O. HUTCHINSON, (middle and right) James EATON/Birdtour Asia]

Reference

Rheindt FE*; Prawiradilaga DM; Ashari H; Suparno; Gwee CY; Lee GWX; Wu MY; Ng NSR, “A lost world in Wallacea: description of a novel montane archipelagic avifauna” SCIENCE Published: 2020.