While walking round the Symphony Lake of the Singapore Botanic Gardens one evening, I came across one half of an eggshell on the ground. The white shell looked too nicely cut round the equator to be natural. So I threw it away.

A few days later Melinda Chan sent me an image of the eggshell of a Pink-necked Green Pigeon (Treron vernans) that she found lodged in the fork of a tree near where a pair of the birds was nesting (left). The white shell looked similar to the one I picked up earlier.

Both pieces must have been discarded by the parent birds immediately after hatching. This is usually the case as leaving the shells around the nest may attract predators. We earlier documented this during the nesting of the Peaceful Dove, also known as Zebra Dove (Geopelia striata) (below) and Little Tern (Sterna albifrons).

Now we come to the question of how come the break in the eggshell is so clean and how was the egg cracked nicely into two.

After the usual number of days of incubation, the developing bird embryo inside is ready to be hatched. Just before this, it develops an egg tooth, a short but pointed structure on the tip of the beak. Near the end of the incubation period the fully developed embryo rubs its egg tooth against the inner wall of the egg. By this time most of the calcium in the shell would have been reabsorbed by the developing embryo and the shell would be very much weakened.

Once the shell is punctured, the egg is said to be pipped. This first puncture is followed by a series of others encircling the blunt end of the egg. Eventually the shell gives way and the chick struggles free. Within a few days after hatching the egg tooth falls off or is reabsorbed by the growing chick.

Once the chick is hatched, one of the parent birds usually removes the shells and dump them some distance away.

Images by Melinda Chan (top) and YC (bottom).

As Tang Hung Bun was walking along Jalan Keli in the late afternoon on 16th April 2007, he spotted a bird flying towards a clump of palms (left bottom). The bird was not behaving normally and this made him curious. It was a Coppersmith Barbet (Megalaima haemacephala) and it was about to enter a hole in a tall, slender trunk of a dead lipstick palm (Cyrtostachys renda) (left top). It was obviously nesting.

He kept close watch for the next four weeks, documenting the nesting with his digital and video cameras – see his webpage.

Coppersmith Barbet is a common colourful resident bird. Most of the time it is found around the tree canopy, often heard but seldom seen. It likes to perch high up on a branch, where it utters its repetitive tonk that sounds like the beat of the coppersmith’s mallet, thus its common name.

The bird excavates a cavity in a semi-rotten tree trunk or branch where the female lays her eggs. According to Madoc (1956) it excavates more than one cavity, using one to lay the eggs and the others to roost at night. The Coppersmith roosts singly, unlike other species where two or more may roost in a single cavity.

Hung Bun managed to distinguish the sexes, although sexual dimorphism in barbets is not strongly marked. According to him the male has a richer red patch across his breast. He believes that there were at least two chicks in the nest. Both parents fed the chicks mainly with fruits, probably figs. Feeding was somewhat interesting. The parent bird flew in with up to three figs in its beak (above left). Arriving at the nest, it looked over its shoulder just once before poking its head into the nest cavity to feed the chicks. Withdrawing its head with a remaining fig, the bird nervously looked around - left, right and left again, checking to see if everything was alright. With a last turn of its head to see whether it was being followed, it poked its head in again. By then a chick had lost its patience and stuck its head out to receive the fig (above right).

After a few visits the female was seen entering the nest immediately after feeding to emerge with her beak full of wastes. Poking her head out, she paused for a while before flying out to dump the waste away from the nest (below). The male was not observed doing this chore. Both parents were observed picking ants from the nest.

Just before the chicks were about to fledge, they would vigorously peck the breast of the parent after a bout of feeding.

On 11th May, 25 days after he first spotted the barbet entering its nest, Hung Bun recorded on video a parent bird trying very hard to pull a dead chick out of the nest. With its beak firmly clamped on the dead chick’s head, it managed to partially pull it out. Only the head was out, but the body was still hanging inside (below left). The bird flew out to return and tried again. Perched firmly on the outside of the nest, it again tried pulling the body out by the head. Again it failed. It flew off again to return with renewed energy (below right). This time it managed to pull the dead body totally out and let if fall to the ground below. The chick was at an advanced stage of development.

The questions that need to be asked are: What caused the death of the chick? Was it killed by its sibling? By one of the parent birds? Can space constraint triggered the killing of the chick? After all the stem of the lipstick palm is 7.5 cm in diameter and the palms where the birds were nesting appear to be more slender than normal.

Another possibility was predation by snakes, squirrels or whatever.

The next few days the parent birds did not fly directly to the nest as was the case before. Instead, they perched on a nearby branch for some time before approaching the nest. This was obviously to encourage the chick to emerge. On 15th May the surviving chick finally fledged. It poked its head out of the nest entrance, stayed that way for a few minutes (right). All the time it was calling softly. It then flew to a nearby tree, continuously calling to its parents. The next day the fledgling was not seen nor heard. It must have flown away with its parents.

The Raffles Museum of Biodiversity Research (RMBR), National University of Singapore, in collaboration with the Bird Ecology Study Group, has just published, as Supplement No. 15 of The Raffles Bulletin of Zoology, “An Annotated Checklist of the Birds of Singapore.” The 179 pages checklist is authored by Wang Luan Keng and Christopher J. Hails. The former is a field ornithologist currently affiliated to the RMBR. She has been actively associated with BESG since the inception of the group. CJH, a director with WWF International, is based in Gland, Switzerland.

This annotated checklist is the third major compilation for Singapore. It lists the current status of all birds ever recorded in the wild. The last annotated checklist was published by C.A. Gibson-Hill in 1949.

The supplement is available at the Botanic Garden Shop.

Most birds feed their chicks with animal food during the few days after hatching, even those birds that feed mainly on fruits and grains. The Oriental White-eye (Zosterops palpebrosus) is no exception. This bird feeds on insects, fruits and nectar from flowers. The young have been observed to be fed mainly on caterpillars. The images above show the chick at various ages being fed with succulent caterpillars. Other invertebrates like spiders and ants are also popular (below). However, no plant food was seen delivered to the chicks. This is understandable, as growing chicks need proteins more than sugars and carbohydrates.

The parent birds are kept busy all day long, flying off to forage and returning to feed the chicks. But when they return, they do not fly directly to the nest. They perch nearby and survey the surroundings (left). Only when all is clear do they fly to the nest. Once the bird lands by the nest, the vibrations will cause the chicks to open their mouths fully, even just after hatching when they are blind. And without fail, every chick in the nest will strain its neck upwards with mouth wide open, ready to be fed.

Unlike raptors and such where the parent tears off pieces and feed the chicks one by one, here, every trip brings only food for one chick. Therefore the oldest and naturally the most aggressive of the chicks usually ends up with the most food. In the recent nesting of the white-eye at Kent Ridge, the original three chicks ended up two. The missing chick, obviously the youngest and weakest, was probably dumped out of the nest by its two siblings or else fell off. This was the case in an earlier documentation where the third chick was found on the ground below the nest.

What becomes apparent once the chick gapes is the reddish colouration of the inner area of the mouth, lined with prominent swollen yellow oral flanges, believed to be “food targets” for the parents (right, arrows).

Immediately after feeding a chick, the adult moves to the rear of the fed chick to await the faecal sac. With its beak, it carefully picks the sac as it appears from the cloaca to disposes it some distance away.

Images by Chan Yoke Meng.

The Asian Koel (Eudynamys scolopacea) is a brood parasite. In Singapore the bird lays its eggs in the nest of the House Crow (Corvus splendens). In India it parasitises the nest of the House Crow as well as that of the Jungle Crow (Corvus macrorhynchos). Once the koel’s egg hatches, the chick will be looked after by the crows until the former is able to fend for itself.

It is thus surprising when Sunjoy Monga reported seeing an adult female Asian Koel feeding a juvenile koel in Mumbai, India:

“Earlier this morning (28th Apr, c. 0730 hrs) when on a walk along Lokhandwala Back Road and near the BMC lagoon (in Andheri west, suburban Mumbai), I came across some weird shrieking calls from the overgrown foliage along the path.

“A closer check revealed the presence of an adult female koel (left bottom) and near it was a wee-bit slender-of-form, much-darkish, speckled bird that she was feeding, in fact just had finished a bout of shoving food in the juvenile’s beak that was responding as is typical of a just-fed fledgling. The juvenile was instantly recognisable as a (full-fledged) juvenile koel that I have seen on numerous occasions earlier (left top).

“A bit too early in the season to see a juvenile koel got me wondering. Then I recollected having seen a Large-billed (Jungle) Crow pair nesting not far a few weeks ago near the electric sub-station not far from here (and which I checked today had fallen off considerably). This species invariably breeds earlier than the commoner House Crow and it is not often that I have come across the Large-billed’s nest parasitised by a koel in this region (in fact I think only on a couple of occasions years ago have Jos and I definitely seen so).

“What was most interesting was watching the female koel feeding the juvenile of her species even as a solitary Large-billed Crow twice made a charge at the scene of activity, evidently to flush away the adult koel who responded with her typically boisterous screams and flew off across into the mangrove and foliage. The young koel meanwhile continued with its hysterical shrieking and the crow appeared as if to feed it but was disturbed by much human movement (morning walkers and a gawking birder I guess) and retreated. A White-eared Bulbul (Pycnonotus leucotis) pair called hysterically which I knew was agitated because their own nest was not very from this spot.

“I waited not far to observe and about two minutes later the female koel reappeared a tree away but was chased away by the crow that arrived at the scene. Pretty soon the juvenile koel too took off across the waterbody with the crow trailing it.

“I made a dash home, about half a kilometre away to pick my camera and try capture this scene and waited an hour more. However, during this time I could not relocate the birds though the crow continued to appear around intermittently and the koel’s familiar crying could be heard in the distance.

“Years ago, we had seen in Kandivli, a female koel feeding a lone koel fledgling. I wonder if any other cuckoo species have been seen feeding their own juveniles reared by another species? Has the koel adult ever been observed feeding juvenile crows too?”

Images by YC.