The Ruby-throated Bulbul (Rubigula dispar (Horsfield)) is known to inhabit the islands of Bali, Java and Sumatra in Indonesia and was until now considered monotypic, that means the populations were not seen as being distinct in any way.

According to a new study, however, it is now known that the birds from Sumatra differ from the others by their bright red instead of yellow eyes, and to some degree by subtle differences of the color of their plumage as well as by having a slightly longer beak. 

The Sumatran birds were accordingly classified as a new subspecies and named as Rubigula dispar ssp. matamerah Berryman & Collar.

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References:

[1] Alex Berryman; Nigel J. Collar: Subspeciation in the Ruby-throated Bulbul Rubigula dispar. Bulletin of the British Ornithologists’ Club 143(2): 237-243. 2023

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edited: 19.07.2023