Persistent detective work and advances in genetic sequencing technology helped researchers at Louisiana State University (LSU) discover a new species of bird on Borneo — the Cream-eyed Bulbul, or Pycnonotus pseudosimplex.
In the lush, lowland rainforests on the island of Borneo lives a rather common, drab brown bird called the Cream-vented Bulbul, or Pycnonotus simplex.
This bird is found from southern Thailand to Sumatra, Java, and Borneo.
In most of its range, it has white eyes.
But on Borneo, however, most birds have red eyes. (Although there are also a few with white eyes).
Eye Color Key to Identification
For 100 years, naturalists have thought the eye-color difference on Borneo was a trivial matter of individual variation.
But persistence and technology advances helped Louisiana State University Museum of Natural Science researchers discover that the white-eyed individuals of Borneo, in fact, represent an entirely new species.
Their discovery of the Cream-eyed Bulbul, or Pycnonotus pseudosimplex, was published in the Bulletin of the British Ornithologists’ Club.
“One of the reasons we knew we had a new species as opposed to just a variant of another species was because the two populations — the red-eyed and white-eyed populations — actually occur together on Borneo,” says Subir Shakya, lead author and LSU Department of Biological Sciences Ph.D. student.
Cream-eyed Bulbul Discovery Made at LSU
One of the theories of speciation is if two birds co-occur in the same area, and they are not interbreeding, then that’s a definitive sign that they are different species.
Shakya made the discovery after returning to LSU from an expedition to Sumatra.
He was sequenced the DNA of several bird specimens from Sumatra and compared them to samples from other sites in the region to determine the degree of genetic relatedness of various species from the different islands and the mainland of Asia.
Several bulbuls from Borneo and the surrounding region were among the specimens he compared.
He found White-eyed and red-eyed birds look almost exactly the same, except for eye color.
The white-eyed Cream-vented Bulbuls from Borneo appeared genetically distinct from all the other white-eyed and red-eyed Cream-vented Bulbuls examined.
Further work to understanding this discrepancy led to the conclusion that the white-eyed birds from Borneo were a new species.
Read about the discovery of the Cream-eyed Bulbul, or Pycnonotus pseudosimplex in the Bulletin of the British Ornithologists’ Club.