Tuesday, 18 November 2008

Uncommon torquatus race of the OHB in Singapore (Toa Payoh)!

Image A: OHB torquatus race seen in Toa Payoh, Singapore. Photo by Gloria Seow.

On the Monday morning of 10 November 2008, I lingered on at home because of the rain....and it paid off. Happened to look out of the windows while working on my computer, and I saw a raptor fly into the grove of trees in front of my house at around 10am. However, the bird got lost in the thick foliage. So I zipped downstairs and after some 15 min of scanning the trees in the constant drizzle, I found the bird huddled high up in the branches above, its back towards me.

I had just met bird photographer Lee Tiah Khee the day before at the Raptor Watch dinner, so I thought of him straight away to help photograph the bird since he works next to where I live (as chief photographer for Chinese newspaper Lianhe Zaobao). He kindly complied...and being the pro photographer, he found us a better angle to snap the bird's front view. The bird was at the same perch, taking shelter from the rain, for at least one hour.

After consulting local veteran birders Yong Ding Li, Alan Owyong and Lim Kim Chuah, they confirmed that it was a resident (non-migratory) Oriental Honey Buzzard (OHB), subspecies torquatus (Pernis ptilorhynchus torquatus). See images A & B taken by Gloria & Tiah Khee respectively. The torquatus race is the resident subspecies of OHB found in Southeast Asia, with breeding records from the Malay Peninsula, Sumatra and Borneo. In Peninsular Malaysia and Singapore, it is regarded as an uncommon resident.

Image B: OHB torquatus race seen in Toa Payoh, Singapore. Photo by Lee Tiah Khee.

In comparison, the commonly-seen migratory OHB is called Pernis ptilorhynchus orientalis and it breeds in Ussuriland, Siberia, visiting Singapore only in the northern winter months (September to March). So, if you see an OHB in the summer months (outside the migratory season), it is likely the torquatus race. Confusion arises when both the orientalis and torquatus races are seen in the winter.

Alan Owyong’s email got me excited:
“I went back and looked at a picture of a 17.5-week old OHB torquatus sent in by Chiu Sein Chiong from Ipoh. It has a very similar plumage (see image C). Several pairs have successfully bred on a tree (by the golf course) in front of his house. I went up there last year to do a video of the fledging. So this bird must have been dispersed from Malaysia. This is quite an exciting find as most of us are not familiar with this SEA (Southeast Asian) resident subspecies. If there are more being dispersed, we may even have our own breeding pair. Gloria, keep looking around the woods at your place.”

Image C: OHB torquatus race of a 17.5 week old juvenile in Ipoh, Malaysia. Photo by Chiu Sein Chiong.

After a google search, I found 3 entries on our local BESG blog of the aforementioned breeding:

Notice that the Ipoh torquatus OHB has a brown face instead of the usual grey in the migratory orientalis subspecies. According to Chiu, the Toa Payoh torquatus OHB is too young to determine its sex. Ding Li helped me map out the various differentiating features between the torquatus and orientalis races:

Oriental Honey Buzzard: Comparison of two races seen in Singapore
Torquatus race (Resident)
* Brown Face
* Long Head Crest
* Rufous Neck
* Dark Gorget (throat)
* Brown Barring on Belly
Orientalis race (Migratory)
* Grey Face
* Short Head Crest
* Brown / Variable-coloured Neck
* Light Gorget (throat)
* Variable belly coloration depending on light or dark morphs
So birders and bird photographers, do keep a look out for the much scarcer resident torquatus OHB race (also known as the Crested Honey Buzzard) in Singapore! Was surprised that even Ding Li has not seen this bird yet in Singapore, but he got it in Terengganu and Panti, Malaysia.
After posting this blog on the various Singapore/Malaysia bird forums, I had a flutter of responses which have been reproduced below, contributing much to the understanding of the resident torquatus race. In response, I have corrected my blog entry above to incorporate the pointers below:
From Gim Cheong, Singapore:
Hi Gloria, great sighting! Ferguson-Lees has split the migratory and resident OHBs (2005). The migratory ones are Eastern Honey-Buzzard Pernis orientalis while the resident ones are Indomalayan (Crested) Honey-Buzzard Pernis ptilorhynchus. The one photographed is thus Indomalayan (Crested) Honey-Buzzard Pernis ptilorhynchus torquatus. I would say it's resident in Malaysia and this individual is the result of 'post-breeding dispersal'. If sufficient numbers disperse here, hopefully they start to breed locally.
From Subaraj Rajathurai, Singapore:
Interesting record Gloria and excellent photos. I would not consider the torquatus race of Oriental Honey Buzzard rare in Singapore though. It is certainly uncommon but we have a few records each year. As you suggested, they may be more overlooked during the winter months (Sep - Mar), when the northern migrants are around. Most records of torquatus therefore come from during the "summer" months, particularly July and August.....the specific period when post-breeding dispersal may take place. One of the best places to encounter this race at that time of the year is at the Singapore Botanical Gardens, where it is annual.

From Yong Ding Li, Singapore:
Hmmmm, I think at this point in time the split is only recognized byFerguson-Lees et al (2005) based on significant morphological differences, at the moment. The latest treatise of honey buzzards based on molecular data, Gamauf and Haring (2004) does not provide support for splitting yet... As an aside, the race torquatus of the Crested Honey Buzzard is an excellent example of avian mimicry. Note that there is a striking similarity of torquatus to Wallace's Hawk Eagle or young Blyth's Hawk Eagles. Similarly the dark Tweeddale morph bears a resemblance to Blyth's Hawk Eagle adults.
From Tou Jing Yi, Malaysia:
Gloria, that's a good sighting, the torquatus is less common compared to the migratory race especially for Singapore. I don't think the species split has been adopted here in Malaysia yet.
From Lim Kim Chye, Taiping, Malaysia:
Hi Gloria, I think more corrrect to say "sub-species" or "race" rather than "morph". *advice taken, corrections made above.* There is one resident OHB morph, i.e. the rare "tweedale" morph in which the generally black & white individual looks very similar to Blyth's Hawk-Eagle. Congrats to you for getting pictures of the resident OHB in S'pore and thanks for sharing the news.
From James Eaton, based in Malaysia:
Hi Gloria, Certainly a very dodgy split! There have been a couple of manuscripts that show Oriental HoneyBuzzard should remain as a single species.Unfortunately I do not have the details at hand of a recent manuscript concentrating on the honey buzzards but the manuscript clearly shows that there is little genetic divergence between any of the taxon. I will let you know once I find it.

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