White-throated Bulbul: an overlooked species?

The genus Alophoixus is one of many genera within the family Pycnonotidae. It is consisted of a number of large bulbuls, mostly with crest. In Thailand, 5 species can be found; 1) White-throated Bulbul (A. flaveolus), 2) Puff-throated Bulbul (A. pallidus), 3) Ochraceous Bulbul (A. ochraceus), 4) Grey-cheeked Bulbul (A. tephrogenys), and 5) Yellow-bellied Bulbul (A. phaeocephalus). None of these species are considered “rare” and can be found quite easily in the right habitat and location. However, I noticed that we actually know so little about them, even the common ones like Puff-throated and Ochraceous Bulbul. In this post, I will only focus on the White-throated Bulbul, a species which I have observed at several places and noticed something interesting about their different appearances.

In Thailand, the White-throated Bulbul has a small distribution restricted to the western border. It can only be found along the Thai-Myanmar border from Mae Hong Son down to Tak and Kanchanaburi. I have yet to see the birds nor photos of them from Mae Hong Son, so this post will only consider the population in Tak and Kanchababuri. Two subspecies have been described and the subspecies burmanicus is presumed to be found in Thailand. The type specimen of burmanicus was collected from Toungngoo around Sittaung River in Myanmar which is quite far west of the Thai border. Apparently, no specimen collected in Thailand has been described.

I first noticed the differences between populations of White-throated Bulbuls when I visited Hornbill Valley in Yunnan, China. There were many White-throated Bulbuls coming to the feeding stations and I noticed that they all looked very different from the one in Thailand. The most striking difference is the colouration of the head and crest. The crown, crest and nape of Yunnan birds are olive-brown just like the mantle. The Thai birds, however, have much paler head and crest with extensive amount of white on the forehead, crown and facial area. The crest is very light greyish-brown, although variable, with luminous yellowish tips. The amount of white on throat is also different between the two populations. The Thai birds have much more extensive white on the throat going down to upper breast, while in the Yunnan birds, the white is restricted only around the chin and upper throat.

Interestingly, when I received photos of the type specimen of burmanicus, they looked sort of intermediate between the Thai and Yunnan birds, probably slightly more similar to the Yunnan birds, except for the more extensive white on throat. The description of the type specimen also doesn’t mention about the extensive white on the face and forecrown, though the olive-green tip of the crest is mentioned. Below is the description of the type specimen (retrieved from The fauna of British India, including Ceylon and Burma. London,Taylor and Francis; [etc., etc.]1889-98. https://www.biodiversitylibrary.org/bibliography/8366).

Criniger burmanicus. The Burmese White-throated Bulbul.
Coloration. Resembles C. flaveolus. Differs in having the upper part of the breast white like the throat, and the crown and crest greyish brown, with the longer feathers of the latter (in good specimens) tipped olive-green. Bill plumbeous white ; iris brown ; legs and feet fleshy brown.
This species, which has long been confounded with C. griseiceps, is very distinct from it, and resembles the Himalayan bird, of which many naturalists may only consider it a race.
Distribution. Toungngoo ; the Karen hills ; Karennee ; Tenasserim, as far south as Meetan at the base of Muleyit mountain, and throughout the Thoungyeen valley. It is doubtful whether it is this species of C. flaveolus which occurs in Arrakan, as recorded by Blyth.

It would be interesting to find out whether the Thai birds are indeed burmanicus or an overlooked taxon. The difficult thing is to find out what the birds in Myanmar actually look like, especially in the field. I find photos of specimens to be quite difficult to judge as the feathers are mostly messed up, so it’s rather hard to tell the exact shade of colour. So far, I haven’t found a single photo of the real burmanicus taken in Myanmar. The few photos that I’ve found were taken further north around the Chinese border, so they basically looked the same as the population in Yunnan. Hopefully, we’ll get to see more photos of this species from Myanmar, especially within the range of burmanicus, although the wish seems quite far fetched considering the current political and health issues in Myanmar. I really wish things will get better, as I’m very eager to revisit this amazing country.