A groundbreaking study has upended long-held assumptions about the Banda Myzomela (Myzomela boiei. This striking honeyeater is found across three remote island groups in Indonesia. Previously considered to consist of two subspecies, researchers now propose that these vibrant nectar-feeders actually represent three distinct species, based on significant morphological and vocal differences that suggest reproductive isolation.
Striking distinctions
The Banda Myzomela has long been classified into two subspecies: M. b. boiei, endemic to the Banda Islands, and M. b. annabellae, found on the Tanimbar Islands and Babar, roughly 350 km south. But a detailed analysis of 28 museum specimens, 21 sound recordings, and 152 playback experiments has revealed striking distinctions among the three populations.
Compared to M. b. annabellae, the boiei form of the Banda Islands exhibits a roughly 10% longer wing, bill, and tarsus, a more pronounced black breast-band, and darker posterior underparts. Most significantly, its song is highly divergent. In playback experiments, Banda individuals showed no response to calls of their supposed southern counterparts. This suggests they do not recognise them as the same species.
Surprise findings
Further surprising findings emerged when researchers analysed the annabellae populations on Tanimbar and Babar. Despite being grouped under the same subspecies, the birds on these two island groups also displayed significant vocal differences. They also failed to respond to each other’s calls during playback trials. Morphological distinctions were also noted, with Babar birds being slightly larger, exhibiting a tail length approximately 10% longer, and potentially having more scarlet on their backs.
New Species
Modern interpretations of the Biological Species Concept emphasises reproductive isolation as a key criterion for species recognition. This has lead the researchers argue that these three populations should be considered separate species rather than subspecies. Since no formal scientific name exists for the Babar population, they have formally described it as a new species.
Lead scientist, Alex Berryman explained: ‘‘The exciting discovery of distinct differences in the three populations of Banda Myzomela led us to propose recognition of three species. In this publication, we suggest these species should be named after the islands in which they are found: Banda Islands Myzomela, Babar Myzomela and Tanimbar Myzomela.’’
This discovery emphasises the importance of Indonesia’s remote islands as biodiversity hotspots, home to cryptic species yet to be understood. It also highlights the need for updated conservation assessments: species once thought widespread may actually have smaller, more vulnerable populations. The study adds to growing evidence that the complex geological history of the Indonesian archipelago has driven speciation in unexpected ways, shaping unique avian lineages that demand further study and protection.
