Here come the sunbirds: New species from Indonesia’s Wakatobi Islands

Here come the sunbirds: New species from Indonesia’s Wakatobi Islands



A group of researchers have identified several new species of sunbirds, whose range spans from Africa in the west and Australia in the east, in the tropical Wakatobi Islands in central Indonesia.

The paper, published Oct. 25 by scientists from Ireland and Indonesia, has described the physical and genetic distinctness of the Wakatobi sunbird (Cinnyris infrenatus) from other known populations. They also found evidence that could split up the more widespread species of the olive-backed and black sunbirds (C. jugularis and Leptocoma aspasia).

“It’s amazing that there are still species waiting to be found in this region, which has been important to evolutionary biology since the time of Wallace,” Fionn Ó Marcaigh, a PhD candidate in Trinity College Dublin’s School of Natural Sciences who is the lead author of the study, said in a statement. He was referring to the naturalist Alfred Russel Wallace, whose major evolutionary findings in the 1800s is referred to as Wallace’s Line, an imaginary divider between deep and shallow seas that lead to marked differences in the species found on either side.

“I’m thrilled that we’ve added to the list of known species from this wonderful part of the world, it’s the kind of thing I dreamed of when I first got interested in zoology as a child,” Ó Marcaigh added.

The Wakatobi Islands (red) lie off the coast of Sulawesi’s southeastern tip in eastern Indonesia. Their collective name is an acronym of the four main islands: Wangi-wangi, Kaledupa, Tomia, and Binongko. Image courtesy of Ewesewes/Wikimedia Commons.
The Wakatobi Islands (red) lie off the coast of Sulawesi’s southeastern tip in eastern Indonesia. Their collective name is an acronym of the four main islands: Wangi-wangi, Kaledupa, Tomia, and Binongko. Image courtesy of Ewesewes/Wikimedia Commons.
The Wakatobi sunbird. Image courtesy of David J. Kelly.
The Wakatobi sunbird. Image courtesy of David J. Kelly.

The researchers collected sample birds on expeditions between 1999 and 2017 across southeast Sulawesi, the land-bridge islands off its coast, Menui and the Wakatobi Islands. They then examined the birds’ physical features such as wing, bill, body mass and their songs. They also analyzed the collected DNA from feathers and tissues and compared them with each sample and those of other sunbird populations.

They found that the Wakatobi sunbird had genetic divergence, shorter wings, a shorter bill and longer tarsi than the Sahul sunbird (C. clementiae) as well as exhibited slower and higher pitched calls over a smaller bandwidth. The Wakatobi sunbird is categorically put by the researchers as the fourth subspecies under the olive-backed sunbird.

The Wakatobi sunbird. Image courtesy of David J. Kelly.
The Wakatobi sunbird. Image courtesy of David J. Kelly.

As the name suggests, the Wakatobi sunbird is restricted to the tiny Wakatobi Islands, off the southeastern coast of the larger Sulawesi. The authors noted that small, isolated islands like Wakatobi had their own evolutionary processes, and they often produced unique species, as in the famous case of the Galápagos.

“The identification of the Wakatobi sunbird serves to remind us that biodiversity is everywhere,” David J. Kelly, a research fellow at Trinity’s School of Natural Sciences, said in the same statement.

The researchers said their findings reiterated recommendations to protect the Wakatobi Islands as an endemic bird area, especially as so much remains unknown to the scientific community. The tiny archipelago is also part of the Wallacea region that many scientists consider “a living laboratory” for the study of evolution with endemic species being newly identified to science in recent years. The region is also threatened by pressures from deforestation due to development that is expected to escalate over the coming decades.

“Our work has identified a cohort of smaller passerine birds on the Wakatobi Islands which appear to have adapted to transitions in their habitat from natural scrub and forestry towards farmed land,” Kelly told Mongabay in an email interview. “While these habitats remain, and the use of herbicides and pesticides is low, the future of these birds should be assured.”

“Sadly, the trapping of birds for the cagebird industry appears to be on the increase,” he added. “I understand it is common for birds to be kept in people’s houses, but the number of people is increasing while the number of birds is decreasing. If nothing changes, the math is simple — the birds will disappear.”

The Wakatobi sunbird. Image courtesy of David J. Kelly.
The Wakatobi sunbird. Image courtesy of David J. Kelly.

In addition to the distinctive nature of the Wakatobi lineage, their work supported the split populations from Sulawesi to the Sahul Shelf, with the Solomon Islands recognized as a species-level taxon, the “Sahul sunbird, C. clementiae,” the Sunda Shelf populations becoming “ornate sunbird, C. ornatus” and the Philippine birds retaining the “C. jugularis” name and taking “garden sunbird” as a common name.

The sunbirds (Nectariniidae) are a family of small passerines with many exhibiting strikingly colorful plumage, which typically indicates their diversity. The researchers noted that sunbirds had been admired by naturalists and artists for centuries, with depictions of the olive-backed sunbird in reliefs on Java’s Borobudur Temple, dating back to as early as the 8th century CE, their search for nectar representing the Buddhist quest for enlightenment. Ó Marcaigh also noted that the Palestine sunbird (C. osea) was used as a symbol of the Palestinian fight for liberation, while many sunbird species found in Africa were considered important pollinators.

“I think the biggest message from this work is that the more we look at biodiversity, the more we realize how local it is, with more and more species being restricted to particular regions or archipelagos or even tiny islands,” Ó Marcaigh told Mongabay in an email interview.

“I hope that having another endemic species recognized on the Wakatobi Islands will empower local wildlife conservationists in protecting this precious diversity,” he added.

Citation:

Ó Marcaigh, F., Kelly, D. J., O’connell, D. P., Analuddin, K., Karya, A., Mccloughlan, J., Tolan, E., Lawless, N., & Marples, N. M. (2022). Small islands and large biogeographic barriers have driven contrasting speciation patterns in Indo-Pacific sunbirds. Zoological Journal of the Linnean Society, zlac081. doi:10.1093/zoolinnean/zlac081

This article by Basten Gokkon was first published by Mongabay.com on 9 November 2022. Lead Image: The Wakatobi sunbird. Image courtesy of David J. Kelly.


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