Notes on Himalayan Swiftlets

It’s been almost 3 years since my last post! With the new social media culture, it has gotten more and more difficult to sit down and write something in length. I guess it’s about time I should do something with this blog to keep it alive and up to date. I decided that I would start with some notes on the “Himalayan Swiftlets” that I’ve photographed recently at several locations.

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A classic look of Himalayan Swiftlet; note uniform dark underparts

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Aerodramus swiftlets are definitely one of the most challenging groups of birds for identification. Most of the times, they can’t even be identified with certainty. In Thailand, there are 3 species of swiftlets within this genus; Germain’s Swiftlet (A. germani), Black-nest Swiftlet (A. maximus) and Himalayan Swiftlet (A. brevirostris). Traditionally, they could be identified based on habitat and distribution range with germani being found along coastal areas both on the eastern and western coasts, maximus being found only along the western coasts and brevirostris in non-coastal habitats mainly in northern and western parts of the country. However, with the booming of “swiftlet condos” built to harvest swiftlet nests, a very valuable product for the Chinese market, it seems that we can’t identify these birds based on habitat and distribution range anymore. Germain’s Swiftlet, a species which produces pure white nest, has already spread throughout the country with many swiftlet condos being built to attract it even in Chiang Rai, the northernmost province, and several places in the north-east, while the extent of range-expansion in Black-nest Swiftlet, a species which also produces edible nest but require some processing to filter the feathers out, is still largely unknown. Himalayan Swiftlet is the only species in Thailand which doesn’t produce edible nest and probably isn’t affected by the business in terms of range expansion. However, the confusing part is that there are 2 populations of Himalayan Swiftlets in Thailand; the resident rogersi and wintering brevirostris and probably innominatus.

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Note dark unifrom underparts

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From my observations in northern Thailand, the area where Germain’s Swiftlet has only known to colonise quite recently (within the last 10 years), I noticed that there are some differences in plumage colouration between Himalayan and Germain’s Swiftlet. On mountains higher than 1,500 m above sea level, a habitat where Germain’s Swiftlet is still not known to occur, I’ve noticed that all the swiftlets showed rather uniform dark greyish-brown plumage with not much contrast between upperparts and underparts unlike in Germain’s where the underparts are generally paler. Of course, this should be judged from similar angles and lighting conditions.

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While rump patch is mentioned to be one of the main characteristics for identification, I find both Himalayan and Germain’s to have a wide range of variation from very pale to almost concolorous with the back. Lighting and angle can also greatly alter the paleness of rump patch too.

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Possibly subspecies ‘brevirostris’; note very long and slender wings and long tail

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Possibly subspecies ‘brevirostris’

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Possibly subspecies ‘brevirostris’

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Possibly subspecies ‘brevirostris’

Lastly, I’ve also noticed some variations among the structure of Himalayan Swiftlets seen and photographed in northern Thailand. Some birds seem to have very long and slender wings and longish tail making them look almost like Asian Palm Swifts. I think these birds are probably the wintering nominate brevirostris which is described to have longer wings than the resident rogersi. I usually see these long-winged birds at lower elevation and cultivated area mixing with other species including those that look like Germain’s Swiftlet, Asian Palm and House Swifts.

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Possibly subspecies ‘rogersi’; note shorter wings and tail

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Possibly subspecies ‘rogersi’

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Possibly subspecies ‘rogersi’

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Possibly subspecies ‘innominatus’; note concolourous upperparts with no apparent rump patch

Sub-Pelagic Trip

On October 18, I had a chance to go out on a boat trip to Phi Phi Island, one of the most popular tourist spots in Thailand. My biggest hope wasn’t for the white sandy beaches or the deep blue water which the island is famous for, but I was hoping to see and photograph frigatebirds which are somehow particularly common in that area.

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Adult male Lesser Frigatebird

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Adult male Lesser Frigatebird

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Adult male Lesser Frigatebird

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Adult male Lesser Frigatebird

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Adult male Lesser Frigatebird

And I wasn’t disappointed. Lesser Frigatebird was indeed quite common. On my way from Phuket to Phi Phi Island, I saw at least 3 adult males and 2 females. While on the way back, I saw 6 males and 2 females. This species is by far the least uncommon frigatebird in Thailand. Most records of stray birds in the Gulf of Thailand and Mekong River are of this species.

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Adult female Lesser Frigatebird

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Adult female Lesser Frigatebird

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Adult female Lesser Frigatebird

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Adult female Lesser Frigatebird

I was surprised to see that there were more male birds than females. I remember the last time I visited Phuket, I saw more female and juvenile-type frigatebirds more often, but that was in spring. Maybe there’s a seasonal change of male/female/juvenile proportion.

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Adult male Christmas Frigatebird

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Adult male Christmas Frigatebird scratching its head

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Adult male Christmas Frigatebird

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Adult male Christmas Frigatebird

But the best thing about the trip was to see adult male Christmas Frigatebirds, a bird now labelled as Critically Endangered by the IUCN Red List. In total, I saw at least 4 adult males throughout the trip. There was also 1 juvenile frigatebird which I’m not confident enough to identify.

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Unidentified juvenile frigatebird

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Bridled Terns were quite abundant but didn’t come close to the ferry. All of them were in the less attractive non-breeding plumage.

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I also had a surprising lifer from Phi Phi Island which was the Pied Imperial Pigeon. A flock of more than 50 birds were coming to a distant fruiting fig tree.

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A pair of adult White-bellied Sea Eagles

On October 17, I also had a chance to visit Thai Muang district in Phang Nga province which is just about 1.5 hour drive from Phuket. The place is well known for the uncommon Spotted Wood Owl which is regularly seen in one of the parks close to the beach. A birding friend of mine from Phuketwas kind enough to take me there.

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Adult Eastern Yellow Wagtail (ssp. tschutschensis) in breeding plumage seen at Phuket Mining Museum

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My first view of the Spotted Wood Owl at Thai Muang

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Many Large-billed Crows came to mob the owls.

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The owls were quite confiding and allowed me to get really close.

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As soon as we arrived at the park, it started raining so badly. We had to stay in the car for about half an hour waiting for the rain to stop. When it finally did, we quickly scanned the park but saw no sign of the bird. After a while, a group of young children came and asked if we were looking for the wood owl. They spread out, ran and jumped from here and there looking for the bird and finally, a pair of Spotted Wood Owls flushed from one tree and moved to another. Needless to say it was a lifer for me and I was really happy to see and even photograph them.

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I’m impressed by the length of wings and tail on this one. It gives an impression that it might be a Black-nest Swiftlet but the tail doesn’t look particularly squarish.

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Can’t say much about this one. Note how the rump patch is not particularly pale.

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Another shot showing the rump

I also took loads of Aerodramus swiftlet photos which were abundant throughout the trip. Most of which I can’t say for sure which species they were. According to the guide books, there are 2 species of Aerodramus swiftlets here, Germain’s and Black-nest Swiftlet.

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Again, another bird with very strikingly long and slender wings but also with a very rounded tail.

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This one has overall shortish structure. I’m pretty sure that this is a Germain’s Swiftlet.

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Apart from the shortish tail, this one also shows a very pale rump patch. Another Germain’s Swiftlet, I’d say.

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Probable Germain’s Swiftlet

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Probable Germain’s Swiftlet

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Another Germain’s Swiftlet showing striking pale rump

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Probable Germain’s Swiftlet

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Probable Germain’s Swiftlet

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This individual has a striking squarish tail.

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Probable Black-nest Swiftlet; note longer wings and tail

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Probable Black-nest Swiftlet

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Probable Black-nest Swiftlet

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Probable Black-nest Swiftlet; note long squarish tail

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Probable Black-nest Swiftlet

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Probable Black-nest Swiftlet

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Probable Black-nest Swiftlet

I’m not saying that these swiftlets are correctly identified and I don’t think anyone can be 100% sure about that, but these are my best guesses according to literature and personal experience. If anyone can give me comments on the identification of Aerodramus swiftlets in the field (and outside the nesting colony, of course), I’d be more than happy to hear!