 This pair of historic photos of a recently discovered Selayar Leaf Warbler was taken by James Eaton, the biologist who originally reported this new species.
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One of the most surprising and dramatic results of field work being conducted in remote areas of Indonesia were the discoveries of 6 new species of songbirds, and 5 new subspecies! Five of the new species were discovered on 2 islands: Peleng and Taliabu, in remote locations described by the authors as a “lost world.” The newly described species are the Peleng Leaf Warbler, the Taliabu Leaf Warbler, the Taliabu Grasshopper Warbler, the Taliabu Myzomela, and the Peleng Fantail, all of which inhabit tropical montane forests.
This is remarkable news considering that globally, the rate of new bird species described per year has been 5 or 6 in the last 20 years! Yet these unexpected discoveries of the 5 new species were found during a single 6-week expedition that integrated research with arduous fieldwork in remote locales. Indonesia is composed of thousands of islands between Southeast Asia and Australia, and in recent years the region has been competing with the Andes Mountains in South America as the region giving rise to the most new bird species discoveries, partly because research teams have been exploring many of the lesser-known islands.
The new bird species were officially reported in recent scientific publications by Frank Rheindt and co-authors, and James Eaton and Alex Berryman, in which they described the new bird species and subspecies. Three of the new species were leaf warblers, a family of small songbird species that differ only subtly in plumage and size, but show more significant differences in their songs and genetics.
Discovering the Selayar Leaf Warbler
The story behind how the Selayar Leaf Warbler was recently discovered is especially interesting: Initially, ornithologist James Eaton spent time exploring the small island of Selayar, located closest to the large island of Sulawesi, Indonesia. There he eventually detected a potentially new leaf warbler species, when on November 30, 2017, heard a singing leaf warbler in an area of mixed second-growth tropical forest. He noted its unique plumage and different song compared to other leaf warblers; however, he wasn’t able to obtain recordings of the bird’s song despite his attempts.
Eaton’s initial discovery prompted a visit to the island in January 2020 by Alex Berryman, who found at least 6 different individuals showing the same plumage traits as the bird found by Eaton in 2017. Berryman obtained good sound recordings of 4 of the birds, documenting the songs to be simpler, with no rambling or squeaky quality to its strophes when compared with the closest birds in this region, the Sulawesi Leaf Warblers.
The new information added support to the idea that the leaf warbler on the isle of Selayar was yet another undescribed species, which remains to be formally given a scientific name. During this fieldwork, Berryman also obtained more sound recordings of the 2 subspecies on Sulawesi, proposing that these should be split into separate subspecies as the Sulawesi Leaf Warbler and the Lompobattang Leaf Warbler.
Alex Berryman described the field situation: Like many recent Indonesian avian discoveries, the clue to Selayar lies in the depth of water surrounding it. Despite lying just 10 miles south of Sulawesi, the strait separating the 2 islands is deep, indicating they’ve never been connected [suggesting the possibility there could be some variation between birds found on the outlying isle]. This led James Eaton to Selayar in the first place, and when he observed a leaf warbler on the island he instantly recognized it as distinct.
Berryman continued: Three years later, James Eaton suggested that I should check out the location and obtain any sound recordings that might help reinforce the distinctiveness of this bird compared to the neighboring leaf warblers on Sulawesi. After arriving at the site described by Eaton, a mostly cleared area of forest, “I heard the unmistakable trill of a leaf warbler, but one that was quite unlike the more complex vocalizations heard on Sulawesi;” Eaton’s suspicion that this was an undescribed species was instantly realized!
This information is especially exciting to share with readers of The Birding Wire, and who knows what other species are waiting to be discovered on these and other Indonesian islands! The above article was prepared from an original article by Jose Luis Copete, provided on the Birds of the World website at https://birdsoftheworld.org/bow/news/indonesia-reveals-yet-another-mystery-an-as-yet-undescribed-leaf-warbler