I work in the Singapore Botanic Gardens and the Grey-rumped Treeswifts (Hemiprocne longipennis) do well here. Outside the Visitor Centre they perch in the big trees, they always select the tallest branches, often dead exposed ones. From there they sally for insects, and I presume they nest, although I have never had a chance to study it. But in 2006 I got the chance. A friend who comes in our shop told me about a nesting pair she had near her home, a high rise development nearby off North Buona Vista Road.

The treeswifts form a small family, Hemiprocnidae in the Apodiformes order which includes three families: treeswifts, swifts and (maybe a bit surprisingly) hummingbirds. Hemiprocnidae is only in the Oriental region and only has one genus with four species. Treeswifts differ from true swift in that they can and often do perch on branches, they are arboreal birds. True swifts form a much larger family (92 species world wide); they spend almost all their time in the air, they even sleep and mate on the wing. They cannot perch on a branch or on the ground, they can only grab a vertical surface with their small, weak feet; therefore they only land when they have to nest, which they do in caves or under cliffs, or under man-made structures like buildings and bridges (a few species fly into tree holes), using the only building material available to them: their own saliva and feathers.

The Grey-rumped Treeswift forms a superspecies and was previously considered conspicific with the Crested Treeswift (H. coronata). The former occurs in the Sunda subregion plus Sulawesi, the latter replaces it in Thailand and Indochina into India. Incredibly, for these widespread and fairly numerous two species there are big gaps in our knowledge of their nesting biology, neither incubation nor fledging periods have ever been recorded (Handbook of Birds of the World, Vol. 5, p. 465). The North Buona Vista pair built a small nest in some dead branches in a tall tree, some 20 meters off the ground, it was clearly visible from the balcony of a nearby building. The nest was a tiny cup made of hardened saliva mixed with minute pieces of what appeared to be bark or moss (above, chicks in nest). When the adult sat on the nest the whole structure was invisible, covered by the bird! We know that the egg was laid somewhere between 7th -11th May 2006, it hatched 3rd of June. I visited the nesting site with my son Adam on 5th June. He took some photos with his digital compact camera - the chick was then 2 days old. Both female and male (recognisable by the rufous ear coverts) took turn attending to the chick and feeding it with a regurgitated substance, presumably somewhat pre-digested insect matter. I visited the site again on 16th June. The chick was bigger of course but still covered in down, still fed regularly and still sheltered completely by one of the parents between feeds. Later on it started to develop feathers, it moved away from the tiny nest and perched on the branch on its own, feeding became less regular. On 1st of July 2006 it left the nesting branch, almost the same hour in the afternoon that it hatched. We now know the fledging period of the Grey-rumped Treeswift: it is exactly 4 weeks! (above, male tending to young; below pair tending to young) So, how is the Grey-rumped Treeswift doing? Well, none of the four treeswifts are globally threatened with extinction. However, the HBW states that ‘Pesticides are suspected to be behind recent population declines in Singapore’. David Wells states something similar: ‘Declining in some suburban areas, including on Singapore main island where the largest party of non-breeders recently recorded was of only five birds’ (The Birds of the Thai-Malay Peninsula Vol. 1, p. 473).

Luckily, in the Singapore Botanic Gardens we still have many more treeswifts than that. The treeswifts like to interact and fly around high together while calling, often late in the day; it is not unusual to see 10-12 birds at one time during those occasions. One evening during ‘winter’ a few years back I was at the exercise ground around 6 pm when a Japanese Sparrow-Hawk (Accipiter gularis) flew quickly by towards the rainforest area, and out of the blue congregated a large flock of treeswifts to mob it. I managed to positively count 35 individuals in the air at one time, but there must have been more, maybe 40. They swerved around excitedly for a few minutes after the hawk had disappeared before they gradually dispersed, many settling around the edges of the rainforest.

Text by Morten Strange; images by Adam Strange.

From mid-October 2005 right through to February 2006, I had been hearing the call of the Asian Koel (Eudynamys scolopacea) almost every morning at about 6.30 am or thereabout. Sometimes I would hear the call later in the morning and once in a while in the evening as well. I have had people complaining of being awaken by the call as early as 4.30 to 5.00 am but in my area the birds apparently wake up later. These birds, there must be more than a pair, roost among matured trees growing in an abandoned area between two housing estates, seldom visited by people. As such I never saw them but always heard their calls.

Asian Koels are extremely shy birds. Years ago they were always heard and seldom seen. More recently they had been making their presence known especially when they visited my Alexandra palms (Archontophoenix alexandrae) to feed on the ripe fruits. But they were still shy, flying off once they noted my presence.

From mid-February 2006 the call dried up to an occasional kwaking. Then around the end of June the call was again heard, but not as regularly as previously.During the first few days of July I had the opportunity to view them close-up. Four male koels flew in at around 5.30 pm and stayed for about an hour to an hour and a half. A bird would suddenly arrive and perch on a fruiting branch of my Alexandra palm accompanied by loud kwaking. Another would soon fly in to be followed by the remaining two. Sometimes they would fly to the Golden Penda (Xanthostemon chrysanthus) tree along the roadside.A pair, perching on different branches but facing each other, would then indulge in duetting. The perching appeared precarious as the birds rocked forward and backward, as if trying to balance themselves. Their tails would flare out somewhat and sometimes they would touch beaks. During this time one or more may regurgitate seeds from earlier feeds. After some time they would simply perch quietly, not moving much and not appearing to communicate. Then suddenly they would all fly off.


A lone male koel was recently seen perching on a branch of the Golden Penda and wailing continuously. As it belted out a series of koel-koel-koel calls, its wings flap up while the tail feathers flare out. This went on for up to five minutes before the bird flew off.

Account and images by YC.

On 3rd July 2006 Gloria Seow spotted a female Pink-necked Green Pigeon (Treron vernans ) sitting in a nest lodged between the branches of a tree (possibly Aphanamixis polystachys). The tree was just behind her first floor office in the MacPherson Road area, near to where the regular office smokers congregated to discuss their battle plans. For the first few days she saw only the female bird incubating the eggs. Only much later did she see the more colourful male at the nest.

The bird would sit quietly in the nest, occasionally shifting positions. The sudden appearance of a Sunda Pygmy Woodpecker (Dendrocopus moluccensis) on a branch close by was totally ignored.

As Gloria recounted: “Showed most of my colleagues the female and male birds with my binos. They were suitably impressed and intrigued that there could be green pigeons in Singapore…” On 11th July the eggs hatched.

“I thought I saw papa regurgitating (at that time I didn’t know what he was doing). He would arch his neck downwards and contraction waves would pass along the length of the body as food pours forth within… Suddenly papa moved and revealed one chick beneath him!” So there were two chicks.
“Papa was feeding the chicks with crop milk every 5 to 15 minutes. When one chick was fed, the other would call out softly in protest. The chicks were covered in yellow down, their eyes appeared to be still closed and sealed within a thin membrane, and they had a yellow beak. I reckon that they were barely 1-2 days old. Papa looked tired, his feathers appeared ruffled and un-preened and he was forever wary of foreign sounds, whipping his head around in alarm with every new aural interference, human or avian made. Thank God such disturbances were few and far between.

“My presence was acknowledged as papa quickly orientated his body and sight line in my direction when initially he was facing the other way. Of course, I posed very little threat as I was seated a good 4 meters below him and every time somebody walked by, I diverted attention away from the nest by fiddling with my other papers and equipment.”

Input by Gloria Seow and images by Chan Yoke Meng - top down: female with chicks, tree where nest was, male in nest, male with chicks. Ali Ibrahim helped identify the tree.

An earlier account saw how a Long-tailed Parakeet (Psittacula longicauda) attacked the nest of a pair of Dollarbirds (Eurystomus orientalis) but was physically evicted from the nest. Here, the attack by a flock of Asian Glossy Starlings (Aplonis panayensis) was under different circumstances.

Meng and Melinda Chan were at Lim Chu Kang when they noticed a pair of Dollarbirds nesting in an open cavity at the top of a dead tree trunk. A small flock of Asian Glossy Starlings was flying over when they noticed the Dollarbirds’ nest. The starlings suddenly flew down to raid the nest. Predictably, the pair of Dollarbirds retaliated, attacking the former. Being outnumbered, the nest was raided and what appeared to be a well-developed embryo was taken away by one of the starlings. The starlings flew away leaving the Dollarbirds to assess the damage.

Thanks to Meng and Melinda Chan for the observation. Images by YC.

Herons are carnivores, feeding on a wide range of live animals found within their aquatic environment. These may include fish, frogs, snakes, lizards, birds and small mammals. They also take aquatic insects and crustaceans.

The long neck and sharp pointed bill are well adapted to harpoon preys. The bird stands motionless in shallow water among vegetation until a prey approaches. It then suddenly seizes it with the bill or if large enough, impales it. An account on the baiting strategy of Little Heron (Butorides striatus) has been posted earlier.

Herons swallow their prey whole. They have an excellent digestive system that takes care of their food efficiently, leaving only bones, feathers, exoskeletons and fur that get regurgitated as pellets.

Adults feed their chicks by regurgitating the prey whole. The chick may swallow the food whole or if too large, the parent bird may break it up into smaller bits.

The image above, provided by Chan Yoke Meng, of a Purple Heron regurgitating a rat, tail-first (it cannot be otherwise) to feed the chick, was taken at Yong Peng, Malaysia in August 2005. Obviously the regurgitated rat needed to be repositioned before the chick can swallow it. Or did it swallow the rat tail first?

The image below by YK Chia shows another Purple Heron, this time a juvenile, with a lizard between its beak. If you look closely, you can see where the lizard had its body pierced.
Thanks to Chan Yoke Meng and YK Chia for the use of their images. Check out YK’s blog.