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Tuesday, February 28, 2006

Of termites and toads

Of termites and toads

Reading Subaraj’s posting on Termite Hatch reminds me that only about a week ago I was trying to explain the same phenomenon to my three year old daughter when we were at the carpark opposite Downtown East at sunset. A flock of House Crows (Corvus splendens) and Javan Mynas (Acridotheres javanicus) was feasting on a termite hatch. A couple of bats also arrived when it got a little bit darker.

Managed to catch one of the 2 cm long termites to show my daughter as it flew past. When I showed it to her, the two pairs of long wings simply dropped off. All my daughter could manage was. “...what happen to the wings? Gone already!"

The sight of those termites sends shivers down my spine. Why? In 1992 I was posted to an old camp in Seletar. We were doing guard duty that night after a heavy downpour and the termites decided to have a nuptial flight.

Initially it was bearable. A few of them were simply fluttering about around the lights. But later, we got a taste of what the Egyptians might have endured in biblical times. The lights were almost blocked out by the hoards, we had to turn off the standing fan because the metal cage around it was almost stuck full of the termites and it was splattering chewed up termites at us. Looked as if someone took a bottle of mayonnaise and decided to decorate the floor around it.

Many of them quickly lost their wings and were all over us and everywhere else. It was actually raining termites. Then the toads appeared in numbers that I have never seen in my life. Almost one toad per square meter at the peak. They were all over the car park and they didn't even have to try catching the termites. They would have been stuffed if they just fed on those termites that were crawling on their bodies.

By about 10 pm, the activity died down. Most of the termites found a quiet spot to congregate. A few toads were still having supper. But we still had to contend with termites getting into our clothes when we went to sleep.

The next morning, when the guards were sweeping up the floor, the heaps of wings that piled up were really a sight to behold. Normally it is the tiny leaflets of the rain tree (Samanea saman) that form the heaps. But not that day! We may not have cherry blossoms (Prunus sp.) here in Singapore, but when the wind blew, the swirling detached wings had a similar effect.

Up till today, whenever I see a termite swarm, it still sends the shivers down my spine and I think of those frantic 2 cm long termites running beneath our army uniforms.

Contributed by Jeremy Lee, image by YC.


Sunday, February 26, 2006

Mistletoes 4: Observations of a sometime bird watcher

Mistletoes 4: Observations of a sometime bird watcher

Nearly every evening in early January, from about 6.00 pm, a pair of male Olive-backed Sunbirds (Nectarinia jugularis) (top) would settle down on my neighbour’s bougainvillea bush and spend some free time preening. In between preening they would simply sit tight, stretch their wings and enjoy the scenery. At exactly 7 pm when it was still light, they would suddenly fly off, where to, I do not know. Some days there would only be one bird.

On other days there would also be a pair of lovey-dovey Oriental White-eye (Zosterops palpebrosus) (bottom). I presume this was a pair, as the two birds would often sit close together, sometimes indulging in allopreening.

The Crimson Sunbird (Aethopyga siparaja) sometimes visit the bush but stayed only for a short while, never resting on a branch for more then a few seconds. They are the ones regularly visiting my noni tree (Morinda citrifolia).

These birds, together with Scarlet-backed Flowerpecker (Dicaeum cruentatum) and Brown-throated Sunbird (Anthreptes malacensis) were always around the mistletoe Macrosolen cochinchinensis when this plant was flowering and fruiting. This semi-parasitic plant grows on the branches of a nearby mempat tree (Cratoxylum formosum) that, thankfully have been left alone and not pruned away by the maintenance crew of the National Parks Board. When the mistletoe plants were flowering and fruiting, these birds enjoyed the copious nectar secreted by the flowers and the succulent berry-like fruits.

Being a regular perching bush of these birds that feed on the mistletoes, the bougainvillea obviously shows signs of the presence of their germinating seeds. These can clearly be seen growing on the stems of the bush (see germinating seed, above), no doubt in time to come, will weaken the flowering bush unless they are removed.

PS: About a month after the above piece was written, my neighbour's bougainvillea bush was heavily trimmed by her gardener. The mempat tree was similarly pruned and most of the mistletoe plants removed, but not completely. I await the return of the birds when the plants grow back to their former glory.


Thursday, February 23, 2006

Caterpillars and birds

Caterpillars and birds

Caterpillars are regularly eaten by birds. However, most birds avoid the noxious ones, especially those that are brightly coloured and hairy. Cuckoos (Cuculidae) specialise on caterpillars as these are their favourite food and they have no hesitation eating even the noxious ones. The arboreal species generally perch motionless on a branch looking for caterpillars. When a one is spotted, the bird grabs it and returns to its perch to eat it. Because caterpillar guts may be filled with indigestible and toxic leaf matters, the bird carefully removes the contents. This is done by biting off one end and gently thrash it against a branch. Once the gut contents are removed, the bird swallows it whole. Sometimes the caterpillar is passed back and forth through the bill to remove the contents. Hairy caterpillars are similarly swiped against a branch, not to remove the hairs, but to empty it of its gut contents. The birds apparently eat the caterpillars together with the hairs, the latter forming a mat in the stomach. These hairs are regularly regurgitated as pellets.

We give below two personal accounts of how two different species of local birds handle large caterpillars.

Robert Teo reported seeing an Oriental Pied Hornbill (Anthracoceros albirostris) in Pulau Ubin that caught a caterpillar of the Atlas Moth (Attacus atlas). This moth is the largest in Southeast Asia and possibly in the world. It's bluish green caterpillar has a series of dorsal and sub-dorsal spines. The hornbill had the caterpillar in its beak and was vigorously shaking it before finally swallowing it.

Tan Hang Chong tells of another incident: "As I was birding along Lorong Sesuai some years ago, I chanced upon a Crow-billed Drongo (Dicrurus annectans). The bird was perched on a tree at eye level and I had the opportunity to observe it for a long while. What caught my immediately attention was that it had one of the largest tan-coloured caterpillar I had ever seen in its beak! The caterpillar was easily 15 cm long and as thick as my finger.

"The drongo started to move the caterpillar along its beak (ala cartoon characters eating a cob of corn). I initially presumed that the drongo was trying to flatten the caterpillar, the better to swallow it later. Thereafter, the drongo turned the caterpillar around, held it on its end and proceeded to swallow it whole. It surely looked like a most uncomfortable feat as the drongo's torso was not much longer than the caterpillar!"

Contributed by Robert Teo and Tan Hang Chong, additional input by YC; image of Atlas moth caterpillar by Angie Ng and of hornbill by YC.


Monday, February 20, 2006

Interspecific interaction of birds at Pasir Ris

Interspecific interaction of birds at Pasir Ris

The place: near the Pasir Ris MRT Station, Singapore. The time: around 8 am. The date: 22nd December 2005. I noticed this whole assemblage of different species of birds on the grass, some foraging, others just looking around. There were crows, mynas, egrets and rock pigeons. More were continually joining in, especially pigeons and crows. The egrets didn't really seem to mind and almost seemed oblivious to the 30-40-strong gathering before them.

Could the spot be a designated meeting ground for birds? After all, birds sometimes do communicate and discuss eating places, like Singaporeans. Or could the spot, judging from the seemingly limited interspecies interactions, be just a good spot for forage or rest? If the latter, it is amazing that there is no or little competition or observable territorial behaviour among different bird species!

Text and image by Lim Junying.

Comment by our bird specialist, R. Subaraj:
I am glad that you were observant enough to notice this. Most people, including many birdwatchers, would have simply ignored the gathering as it mainly involved common urban species.

Based on the photo and what you have written, I would think that the area is a good feeding site. The Cattle Egrets (Bubulcus ibis) normally hunt insects in fields and the mynas and crows are opportunists who would also catch and eat insects. The patch of grass may be rich in invertebrate life due to some unknown reasons (dampness, freshly cut grass, etc.). As for the pigeons, they may focus on seeds but could be eating invertebrates as well, being highly adaptable.

As for competition, if there is plenty about there should be no problem. However, it may be interesting to study if they are working as a team, in a birdwave of sorts. A birdwave is a gathering of insectivorous bird species that move together to stir up more insects. This is a common occurrence in forests, from the lowlands to the mountains. The more birds involved, the more insects are stirred up and the better chance of finding a buffet, such as a tree of caterpillars.

Does this behaviour occur on the ground and in more open country or urban settings? Should be fun finding out.

Keep at it and nature never fails to amaze!


Saturday, February 18, 2006

Yellow-vented Bulbul does swallow some fruits but not others

Yellow-vented Bulbul does swallow some fruits but not others

In an earlier posting it was said that Yellow-vented Bulbul (Pycnonotus goiavier) does not swallow Alexandra palm (Archontophoenix alexandrae) fruits. It pecks on the outer pulp, leaving the fruit on the branch with patches exposing the seed.

With the MacArthur palm (Ptychosperma macarthurii) (above), I have noticed that this bird does swallow the fruits whole. Although I have not seen it regurgitating the seeds, I did find a few patches of faeces with seeds on my driveway. It is possible that the bulbul passed out the seeds?

However, I have been puzzled by the presence of many individual seeds of this palm, cleaned of pulp, scattered along my driveway (left). I do not grow this palm in my garden. These seeds must have been regurgitated by some birds. Can it be the Pink-necked green Pigeon (Treron vernans) that regularly perch on the overhanging ceram palm (Rhopaloblaste ceramica) fronds?

And why does the bulbul swallows fruits of the MacArthur palm but not those of the Alexandra palm? The answer lies in the size of the two seeds. Alexandra palm fruits are nearly round, 12x10 mm, with a single large round seed that is about 9x8 mm in dimension. The flesh is a thin layer of 2-3 mm thick. Although the fruit of the MacArthur palm is of similar size, the seed is very much smaller. It is 10 mm long but only 5 mm broad.

Obviously we have much to learn about the feeding habits of our common birds.

Transverse sections of fruits of MacArthur (left) and Alexandra (right) palms.

Seeds of MacArthur (left) and Alexandra (right) palms.

Scale in mm.
All images by YC.


Friday, February 17, 2006

I and the Bird #17

I and the Bird #17

We are participating in the latest I and the Bird festival #17 whose theme is "Wildbirds on the Fly." Do visit the site and read our submission on "The World is My Saucer!" by Joseph Lai.


Thursday, February 16, 2006

Forensic Birding 1: Introduction

Forensic Birding 1: Introduction

We were introduced to forensic birding by Lin Yangchen when he wrote on 30th December 2005:

“Birds are usually identified by sight or sound. It may also be possible to identify them from the tracks, feathers and droppings they leave behind. It is not always possible to pinpoint the species but the genus or family may be established. Looking out for signs is one challenge and interpreting them is another.

“For example, tracks can divulge much information through the presence or absence of claws and webbing, the number and apparent relative lengths of toes, angle between toes II and IV etc. The arrangement of a series of tracks can reveal characteristic gaits and whether the bird was walking, running or hopping. Slightly unfortunate, bird tracks are usually found only on the ground in silt, mud or snow.

“Cracked nuts, half-pecked fruits and pellets might tell us about diets and feeding guilds while the condition of a bird skeleton might tell us how the bird met its demise (cat, bird-eating spider, car accident etc).

“This is a fascinating subject either for research or for fun, as the eggs of the warring crows and koels have demonstrated.

“Since the days when the wild regions of the Malay Peninsula were largely unknown, explorers have taken a keen interest in the evidence left by animals. For example, *Skeat (1908) observed 'peculiar open spaces several yards square and absolutely devoid of leaves and rubbish' along a ridge on Gunung Tahan. The footnote reads, 'they are nothing more than the playing-grounds of the Argus Pheasant'".

Responding, Benjamin Lee wrote, “Thanks for the enlightening account of avian CSI. And let's not forget the application of avian forensics in determining species causing aircraft engines to fail during a bird strike. Dr Jon Baldur Sigurdsson, who used to teach ornithology in the former Department of Zoology, National University of Singapore, was a consultant to bird strike cases at Changi Airport. He had to determine what sort of birds were killed by looking at the remains of feathers, bones and bits of skin.

There is an excellent review article here on everything you want to know about aircraft and bird strikes. This article is reproduced from "The Auk", an American ornithological journal, and was authored by Prof. Navjot Sodhi from the National University of Singapore."

See also "Tales of a Birding Pilot".

Wang Luan Keng followed with a workshop on 20th January 2006 when she brought specimens of feathers and wings, eggs, skeleton pieces, whole bird specimens, etc for participants to handle and ask questions. The evening proved to be an exciting introduction to forensic birding with participants showing much interest and asking numerous questions.

Obviously there is a wide-open field out there for birders to look into. Birding is not and should not be confided only to identifying birds and counting them. Birders, when out in the field, should also look out for bird tracks, splats, discarded eggs and shells, make the necessary records and bring them up for discussion later.

Input by Lin Yangchen, Benjamin Lee and Wang Luan Keng. Image by Lin Yangchen.
*Skeat, W. W. 1908. A personal reconnaissance of Gunung Tahan. Journal of the Federated Malay States Museums 3:77-90.


Tuesday, February 14, 2006

Angie’s nesting crows 5: Final chapter

Angie’s nesting crows 5: Final chapter

After only three days trying to incubate their eggs, the House Crows (Corvus splendens) gave up on the morning of 28th December 2005. Thereafter, it was open house for the Asian Koels (Eudynamys scolopacea)! They were increasingly daring, stealing into the nest throughout the day, but the height of activity was always in the mornings and late afternoons, and one female even stayed in the nest for more than 10 minutes. There were two occasions when the male koel took an interest, hopped into nest, looked around before hopping off again.

Although the crows seem to have abandoned their nest, they are not averse to visiting it every day, and sometimes twice or three times a day - to check on the contents? Once I saw presumably the female pecking, pushing and pulling some of the twigs. It seemed to be tidying the nest or doing some house-keeping! However, on another day one crow actually took away some fine twigs from the nest!

I would know they were visiting because often they would caw but other times I just happened to look up and there they were! The crows would still chase away the female koels if they chance to see them approaching the nest, but I think they are losing interest. They behave as though they have another nest somewhere else. Lately, they sometimes fly overhead by-passing our tree. Female koels still visit the nest, though not as frequently.

And throughout the days I was home, a lone male koel would spend long periods sitting on the lower branch mournfully calling 'koe-ell koe-ell' its pitch gradually rising in desperation.

The nest looks a little thread-bare/twig-bare this morning.

If each time a female koel visits and lays an egg, we'd have more then two dozens eggs in nest. But do they necessarily lay eggs at each visit?

This is the end of koel-crow watching, I hope. Maybe I will still watch to see when the nest will drop its load of eggs!

Just after writing the above and when I was sweeping the floor, four crows flew up to branches near the nest. One had some food (?) in its beak, flew into the nest, moved around and came out before another crow went in. This crow cawed and fussed around, unsure whether to sit in or leave. While the other three crows left, this crow hopped to an adjacent branch, sharpened its beak, looked around, spied a female koel hiding in the far end of tree and chased it all the way to Lewis Road.

Who are these four crows? Obviously two couples. Is one pair the owners of the nest?

Contributed by Angie Ng, 14th January 2006; image by YC.


Sunday, February 12, 2006

Cats in Australia

Cats in Australia

Cats are an absolute no-no in Australia, where essentially they are non-native and imported by thoughtless white settlers in the 18th and 19th centuries, who even more thoughtlessly let them go 'feral' in the wild (believe me, these seeming pussy-cats are like wild leopard cats if cornered, hissing masses of aggression!) etc. They have wreaked havoc with small native mammals (mostly nocturnal) and birds. In several eastern states, owners have to have licences for them and must observe a legally enforced 'curfew' banning them from wandering outdoors by night on pain of fines and other penalties, within the confines of a defined 'metro' urban area - in the countryside, they have been banned completely in several cases - and should be. There have been suggestions that ordinary owners only be allowed to keep cats if they are sterilised and only licensed breeders may actually breed cats.

When I first arrived in Western Australia, my garden came with about 6 dependent stray cats attached! And I had kept a couple of my own, with dogs, in Singapore before. But as I learned more about the Australian ecology, I came to the conclusion that I must harden my heart and get rid of my own cats - I took them one by one to the local Cat Haven, whence they were 're-homed' (a bit of a cop-out, I know, since they were still in the Australian ecology!). The payoff has been abundant birdlife in my garden, where I cultivate native plants to attract the local birds.

It's an interesting example of how animal welfare concerns often have to be traded off against conservationist concerns.

I wonder if all countries need to consider similar measures for the protection of wildlife? And I wonder how much research has been done on how 'native' domestic cats are to SE Asia?

Contributed by Ilsa Sharp, from Perth, Western Australia

Additional input by R. Subaraj:
Unlike places like Australia and New Zealand, cats in Singapore are largely confined to more urbanised areas and feral cat populations are almost entirely found in the city and housing estates (see Cat Kill. Apart from the very occasional individuals, one does not come across cats in nature areas. Perhaps our Reticulated Pythons have something to do with that....! Dogs on the other hand are a problem with stray populations in many nature areas including our reserves of Bukit Timah, the Central Catchment and Sungei Buloh. They form packs and hunt our native birds and other wildlife. The first Lesser Mousedeer (highly endangered and a distinct endemic subspecies) I ever encountered in Singapore was one being pursued by three feral dogs within our Central Catchment Nature Reserve!


Thursday, February 09, 2006

To swallow and regurgitate? Not the Yellow-vented Bulbul!

To swallow and regurgitate? Not the Yellow-vented Bulbul!

My Alexandra palms (Archontophoenix alexandrae) are fruiting again. The large bunches of red fruits invariable attract Asian Glossy Starlings (Aplonis panayensis) that are a delight to watch, what with their iridescent dark plumage and bright red eyes. I was pleasantly surprised to observe earlier that these birds swallowed the fruits whole but soon regurgitate the seeds after the pulp had been removed in the gut.

Reviewing my earlier images of koels caught in the act of raiding these fruits, I found that I have evidence that Asian Koels (Eudynamys scolopacea) regularly swallow the fruits (see above) but have yet to actually see them regurgitate the seeds.

Yellow-vented Bulbuls (Pycnonotus goiavier) are similarly attracted to these fruits, but only when the starlings are not around. But these bulbuls apparently have a smaller gape than the above two birds as they are not able to swallow the nearly rounded 10x12 mm fruits. Instead, they peck on the red fruits to remove pieces of the soft outer covering, leaving the fruits with patches exposing the seed surface still attached to the bunch.

Obviously the starling, koel and bulbul are inefficient seed dispersers as far as the Alexandra palm is concerned. Depositing the seeds at the base of the parent palm is not advantageous to the plant at all.

I wonder whether there are any animals that actually disperse these seeds. As an exotic palm introduced from the warmer regions of Eastern Australia, it is very possible that the seed dispersers are absent in Singapore.

Comment by R. Subaraj: It would be interesting to find out if some of our local animals like plantain squirrels, actually help disperse the large seeds of some of our exotic palms.


Wednesday, February 08, 2006

Bald headed mynas

Bald headed mynas

I am only a sometime-ornithologist and one that looks mainly at dead birds. I don't know the real reason why mynas appear bald-headed at times. Our local myna expert, Dr Kang Nee, noted this phenomenon of botak (Malay for bald-headed) Common Mynas (Acridotheres tristis) when she studied them in the late 80s and early 90s. She noted that birds that have their crown feathers actually do not have the yellow skin on the head. It's only when the feathers are gone that the skin turns yellow. Why? Don't know. Did the feathers drop off because of moult or fighting? Don't know. She never obtained any observations even though she spent several years studying and radio-tracking them in the wild and breeding them in captivity.

I have also written to the world's leading sturnid expert, Dr Chris Feare many years ago about botak mynas. He knew about them but couldn't offer any explanations either.

I think it might not be typical moulting, otherwise all Common Mynas would have the botak head at every moult cycle, which is usually once a year, and you should see a very high percentage of botak birds in the myna population.

Do mynas that are timid and smaller get pecked on the head until they are botak or do birds become more timid after they become botak? I have no answer. I wish I could lay my hands on some of these botak birds so that we may learn something from them.

Contributed by Wang Luan Keng in response to queries about these strange birds


Sunday, February 05, 2006

Mistletoes 3: A naturalist's account

Mistletoes 3: A naturalist's account

I have been tending mistletoes growing on my sui mei (Wrightia religiosa) and chillie (Capsicum annuum) plants for a couple of years now and seen the different stages of its growth and death!

There were three species of mistletoes growing at my old place: Dendrophthoe pentandra, Macrosolen cochincinensis (left) and M. retusus.

Seeds of D. pentandra grew and flourished on both the above plants and also on my limau perut (Citrus hystrix) [see seed germination]. These mistletoes attracted butterflies like Peacock Royal (Tajuria cippus maxentius) and other unknowns whose eggs hatched into queer caterpillars on my balcony. D. pentandra also attracted the lovely Painted Jezebels (Delias hyparete metarete), whose caterpillars will only eat leaves of this species. The flowers of sui mei attracted many sunbirds and flowerpeckers!

Seeds of M. cochinchinensis deposited on my sui mei never grew. In the garden below, D. pentandra and M. cochinchinsis were flourishing on the white champaka (Michelia alba), mock orange (Murraya paniculata) and mango (Mangifera indica) trees. It also grows on the guava (Psidium guajava) tree in my aunt's garden (that's where I got one batch of Jezebel babies). The M. retusus was found growing on mock orange. I know of other trees with D. pentandra - I often had to collect extra supplies for the ever hungry Jezebel cats!

I've seen the Olive-backed Sunbirds (Nectarinia jugularis) and Scarlet-backed Flowerpecker (Dicaeum cruentatum) (left) feasting on the fruits of D. pentandra and M. cochinchinensis. But I've seen only the male flowerpecker defecating the mistletoe seeds!

Contributed by Angie Ng, images by YC


Friday, February 03, 2006

What happened when a nestling fell out of its nest?

What happened when a nestling fell out of its nest?

Margaret Heng
, a member of the Singapore Gardening Society, read my article on the Pink-necked Green Pigeons (Treron vernans) in the society's newsletter the Grapevine (see also) and sent me the following e-mail on her encounter with a displaced Spotted Dove (Streptopelia chinensis) nestling some time ago. The account is so fascinating that I got her permission to share it with others:

“Your articles in the Grapevine are always so interesting and enlightening! Thank you for sharing your 'nosy' experience with the pigeons. It was great! It reminds me of my daughters (when they were very little) and I when we found a baby Spotted Dove in our garden some years ago.

“One of its legs was injured. We picked it up and treated the wound with gentian violet (it’s our usual treatment for wounds), then we placed the bird in a shallow tray with some towels at our side patio table. When I woke up the following morning we could hear the cooing of a pigeon coming from our roof. We rushed to check our baby bird from behind our glass sliding doors (with drawn curtains of course) and lo and behold the baby was responding much to our delight! The mother had found its babe!

“The next amazing thing was that she flew to the baby and with a noisy exchange of greetings the mother grabbed hold of the baby’s head with wide opened beaks and shook it up and down. My daughters were horrified! I had to tell them that’s how the mom feeds the baby.

“From then on our side patio table was our stage for 'bird show.' We peeped quietly behind the curtains, even tried snapping pictures! The mother bird soon taught the baby how to jump out of the tray, down to the floor, and how to peck at nothing on the floor and so on. It was so funny.

“Just before the week was up it was time to try flying! The first flight from the top of our retaining wall to the top of our neighbor’s porch was a disaster. Plop, down it went. But after that it was plain sailing and we had to bid them farewell.

“Sorry for this long-winded sharing. It’s just that we enjoyed that experience! Thank you once again for all your articles in the Grapevine.

Margaret Heng"


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