Sometime in November 2006, KC Tsang posted the image on the left (top) and noted, “We need a forensic expert here to find out who was the victim of this very explosive feeding frenzy. And who is the possible perpetrator of this crime most foul? Scene of the crime, not in KL, but in our very own backyard.” Note that the above consists of different feather types that lead one to conclude that the bird was a victim of a predator. Was it a cat? A raptor? The jury is still out.

My experience during November 2006 was different. I kept finding in my garden and driveway a large number of most probably belly feathers (left bottom). I have not seen them before, maybe because I did not look closely or because they were not around.

My guess was that the feathers belonged to the Pink-necked Green Pigeons (Treron vernans) that were around my pair of ceram palm (Rhopaloblaste ceramica). This was the time of the year when these pigeons regularly perched along the midribs of the palm fronds in the early mornings and late evenings.

At first I thought a pigeon might be victim of a predator and the scattered feathers were evidence of what happened. But then there were no other types of feathers around. Then the possibility of moulting came to mind. Intrigued, I sent an image to our field ornithologist, Wang Luan Keng for her opinion.

Her reply: “Those are not pure down feathers but semiplumes and they are the belly feathers of the green pigeon. The distal part of the feather helps to fill up the contour of the bird where the downy part is mainly for insulation and are covered by the feather on top. These belly feathers are quite loosely attached to the bird and can drop out easily - an adaptation to scare predators. These pigeon feathers that you found underneath your palms may not be due to moult.

“Birds do have a period to moult, usually after their breeding season. In Singapore, most birds breed from Feb/March till July/Aug, maybe Sep. Many species here overlap moult and breeding slightly so they will start moulting in July/Aug and end by Oct/Nov when the NE monsoon starts. Many species, especially passerines, have straight forward sequential moult; others like cuckoos, hawks, herons, fruit doves etc have very complicated multiple moult series and yet some species like rails, grebes and probably bitterns moult all feathers at once and go flightless during that period. And mind you, we are only talking mainly about primary feather moult. We know even less about other flight feather moult and almost nothing about body feather moult.”

Input by KC Tsang, YC and Wang Luan Keng. Images by KC (top) and YC (bottom).

Pigeons and doves, belonging to the family Columbidae, are either grainvorous or frugivorous, eating seeds or fruits respectively. This does not mean that these birds eat exclusively seeds and fruits. Many also eat invertebrates, especially insects, worms and snails.

However, unlike other plant-eating birds that initially feed their chicks on soft invertebrates like insects and spiders, pigeons and doves feed theirs on a sole diet of crop milk, also called pigeon’s milk, especially during the first few days after hatching.

This crop milk is a highly nutritious surry of fluid-filled cells that slough from the lining of the crop. It is rich in fats and vitamins A and B. It is said to be richer in protein and fat than cow’s milk or even human’s milk for that matter. It consists of 12% protein. 6% fat and 1-2% minerals and amino acids, the remainder being water but no carbohydrates.

The young squab stimulates the production of crop milk by putting its bill into the buccal cavity of its parent, which in turn touches the sensitive sides of the nestling’s gape to make it open up (left: top, middle). The adult bird then regurgitates this crop milk directly into the throat of the young.

You may ask why is it that these birds do not feed their young with the same food that the adults eat? The main diet of the adult is plant materials and these are not digestible to the young during the initial stages of their development. As the young develop, their diet includes an increasing proportion of plant materials until finally they are fed the same diet as the adult.

As the chick gets ready to be fledged, they are fed more fruits and less crop milk. In the lowest image, the chick has a fruit, probably a local cherry (Muntingia calabura) in its bill.

The above images are by Chan Yoke Meng who documented the nesting ecology of the Pink-necked Green Pigeon together with Gloria Seow, a full account of which can be seen in Gloria’s blog.

The series on the Zebra Dove has been incorporated into the publication below and as such Zebra Dove 1-19 have been deleted:

Wee, Y. C. & L. K. Wang 2008. Breeding behaviour of the zebra dove, Geopelia striata (Linnaeus, 1766). Nature in Singapore 1: 75-80.

A PDF copy is available HERE.

It is reported that both the male and female Pink-necked Pigeons contribute to the building of the nest. The former sources for nesting materials while the latter sits in the nest site and construct the nest.

As with all pigeons and doves, the nest is a crude platform of twigs lodged firmly between the lower branches of a tree. I suppose nest materials will depend on what are available nearby. Around my area twigs from mempat trees (Cratoxylum formosum) are commonly used.

My Dracaena reflexa Song of India tree had seen two nestings, in February 2000 and again in February 2005. Around my area these birds also nest in wild water plum (Wrightia religiosa) bush and cockscomb (Erythrina crista-galli) tree. I am sure they nest in other plants as well.

If you walk past a tree and suddenly experience a noisy flight of a bird out of the crown, it is possible that you may have disturbed a nesting pigeon. Look closely, and if you spot a nest, please do not disturb it. Just make regular but discreet observations.

These birds usually lay two white eggs. In the first nesting both eggs hatched and the two nestlings eventually fledged. With the second nesting only one bird survived as one of the two eggs was displaced when the parent bird flew off in fright when I walked by the tree earlier on.

Examining the nest after it had been abandoned, I found the periphery covered with dried faeces. Apparently the birds must have aimed outwards when they did their business while still on the nest.