This is my detailed obervations of the nesting of the Pink-necked Green Pigeon (Treron vernans) in Singapore. For those who want a quick idea of what it is like to observe this dedicated pair tend to their young, watch my youtube video first. I have 11 video segments in all, this is just one of them... http://www.youtube.com/watch?v=HNp-3eDerss
28 June to 10 July 2006
I spotted a Pink-necked Green Pigeon loitering at a tree just behind my 1st floor office, right at the table where the smokers discuss their battle plans. This was on 28 June 2006, while we were having a company meeting. The next day, I brought my binoculars and realized that there was a nest right on a truncated flat portion of a thick branch to the right of the main trunk, 6-7 meters above the ground. The tree is possibly an Aphanamixis polystachys, as identified by a local botanist.
For the first few days, only the female was seen incubating the eggs. These birds sit there 24/7, shifting positions only very occasionally. Even a Sunda Pygmy Woodpecker landing close by didn’t ruffle the calm creatures. Showed most of my colleagues the female and male birds with my bins. They were suitably impressed and intrigued that there could be green pigeons in Singapore instead of the usual black ones (Rock Pigeons). Since the stupid office is so freakin’ cold (averaging 18°C, once it plunged to 16.7°C), every time I try to shoot my birds, both my camera and bins need to defrost for a good 15 minutes, which makes matters frustrating especially when something could be happening at the nest.
11 July (Tuesday) – Day 1 of Hatching
Papa feeding his 2 day-old chick
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 his body as food poured forth from within. One of my good friends came by to photograph my nesting birds at around 4pm, just before departing for her HK trip. Suddenly Papa moved and revealed one chick beneath him! She managed to catch 2 pictures of this, albeit a little blurred, due to her excitement. After that, the bird continued sitting in the nest, blocking all views of the chick.
12 July (Wednesday) – Day 2 of Hatching
Helpless Babes in Yellow Down Feathers
Tried out my colleagues digital video camera and found that the 20x zoom function was pretty good, filmed a nice sequence of the baby being fed!! First time I was using the tripod I bought. I observed the nesting chicks for an hour or so during lunch - there are 2 of them sitting in a tiny pocket of space at the front of the nest, just below the twigs level. Papa sits in with them the whole time, regurgitating crop milk every 5 to 15 min to feed the hungry ones. Can only see the nestlings when they crane their hungry necks for Papa's fodder. Even heard one of them little 'uns call out in protest when it was his brother's turn to eat. The chicks will poke their little beaks into the base of Papa's much bigger pecker to gulp down his crop milk.
The babies are covered in yellow down, their eyes appear to still be closed and sealed within a thin membrane, and they have a yellow beak. I reckon that they are barely 1-2 days old. Papa looks tired, his feathers appear ruffled and un-preened and he is forever wary of foreign sounds, whipping his head around in alarm with every new aural interference, human or avian made. Thank God such disturbances are few and far between.
My presence is acknowledged as Papa quickly orientated his body and sight line in my direction when initially he was facing the other way. Of course, I pose v little threat as I am seated a good 4 to 5 meters below him and every time somebody walks by, I divert attention away from the nest by fiddling with my other papers and equipment.
13 July (Thursday) – Day 3 of Hatching
Prof YC Wee, the founder of Nature Society (Singapore)’s Bird Ecology Study Group which has its blog at http://besgroup.blogspot.com/ told me about the day/night duties of the PNGP. The male does nest duties during the daylight hours, leaving the nest around 5pm. The female takes over then, staying throughout the night till about 7 to 8am. Usually two eggs are laid and both chicks fledge. Incubation takes about 17 days and a further 10 days before the chicks fledge.
Cozying up to Papa.
Hunting to a Duty Roster
For my pigeons, nest duty schedules were not as defined as delineated by YC Wee, at least during the incubation period. Either sexes could be sitting at the nest during the day for hours on end. Its fascinating that pigeons differ from other birds species that have to leave their chicks unattended as they go out to hunt for food. Instead, pigeons regurgitate crop milk (read: digested / partially digested food), and hardly ever leave their chicks alone for long. In the initial days following the hatching, either parent would be at the nest 24/7. Eventually, my pigeons also followed YC’s pigeons’ duty roster, male – day duty, female – evening/night duty. Obviously, the male has it harder, as he has to hunt by night. Only when the chicks were older (above 7 days old), did their parents abandon the nest for short periods of time to do their own stuff.
So by hunting to a duty roster and regurgitating crop milk, our pigeon friends can feed their chicks round the clock, plus look out for predators. Win-win eh? Perhaps it explains why populations of pigeons around the world are exploding! Especially the Rock Pigeons. Even PNGP are abundant in the wilder parts of Singapore and Malaysia.
Fecal Sacs or Splattering Poo?
(This was written before a later insight). I don’t know if baby pigeons excrete fecal sacs like Yellow-vented Bulbuls or do they simply splatter their poo, like they do on our cars! Apparently, some birds eat the poo of their nestlings during the first few days as the chicks’ digestive systems are not 100% efficient then, and the "recycled" food is thus not wasted. As the nestlings grow bigger and their digestive systems become more efficient, the parent birds dispose the poo away from the nest to avoid detection by predators. YC never saw any faecal sacs being removed from his own nesting PNGP. After they left the nest, he saw some mess around the edge and plenty of white wastes below the nest and on the leaves around the nest.
15 July (Saturday) - Day 5 of Hatching
Attack / Defense posture, in response to a crow’s caw.
Threats to the Nest
Meng and Melinda stayed with the nesting Papa Pigeon and Chicks from 1130am to 430pm. They observed that the chicks were relatively inactive and inconspicuous. Both chicks were spread out in the nest, each taking opposite ends of Papa’s wings. Only during feeding did they cluster at the front, impatient for a share of Papa’s offerings. A crow cawed nearby, prompting Papa Pigeon to rear its hind end, angling his body downwards in an attack/defense position. I observed and even filmed this phenomenon earlier in the week when some unseen threat descended upon the nest.
As usual, foreign noises that appear out of the blue would cause Papa to cock his head to one side, better positioning his ear to determine the degree of threat. It seems like Papa is more sensitive to higher pitch sounds than low pitch ones. Three stray cats were observed in the vicinity, but as yet, the nest has thankfully gone undetected.
16 July (Sunday) – Day 6 of Hatching
The 3 of us patiently sat down to photograph and film the various going-ons in the nest. Meng and Melinda stayed from 1130am to 4pm. I came at 115pm and stayed till around 445pm. Lighting at the nest was highly variable, alternating between periods of shadow and intense sunlight.
Description of the Chicks
The 2 chicks are a lot bigger now approximately 12-13cm in size. They are cloaked in a coarse down that is speckled black and white with bits of yellow. However, not all parts of their body are covered, as their peachy flesh shows through their napes. Their beaks have morphed from yellow to a peachy tone, with the tips further ringed by a narrow band of black and yellow at its curved end. Wing feathers have long streaks of black and yellow running through them. Their heads are oddly shaped, not smooth and rounded like Papa’s, but with the two eye cavities proportionately larger than the cranium, creating an appearance of protruding eyes. Eyes do not have a red ring like Papa’s and irises are black in colour.
My darling birds! Taken by a lovely bazooka camera. The chick on the left looks like a one of those Super Hero characters.
Behaviour of the Chicks
The chicks alternate between bouts of activity and inactivity. Slow periods can stretch for close to ½ hour, interspersed by precious filming / photographing time of action that lasts 5 to 15 minutes. Today, they have started to stretch their wings and occasionally flapped them rather vigorously, exercising their appendages in preparation for flight. They are constantly changing positions, tunneling under Papa’s feathers to get from one part of the nest to another. Papa had to shift his body around the restricted confines to make room for his rapidly growing chicks and to accommodate their energetics.
These chicks also feed much less frequently, the same way as before, crop milk from Papa’s pecker. Usually, they are the ones to initiate feeding, pecking at Papa’s beak to indicate their hunger. Papa would then vomit his contribution, his tiny body moving to rhythmic spasms as his internals contract to force up its contents. The chicks can be seen preening themselves, with Papa helping to straighten out their feathers, pecking them gently on their heads and sides in a heart warming gesture of family love.
When resting, the chicks like to snuggle up to Papa’s feathers for warmth and comfort, or treat the sides of the nest as a pillow of sorts, resting their tiny heads on the jumble of twigs and shutting their eyes for some snooze time. Most adorable! This is when Papa Pigeon settles down contentedly for some shut-eye of his own.
Change of Shift
From my estimation, change of shift with Mama Pigeon occurs around 530 to 6pm. However, I have not exactly seen this happen yet, nor have Meng or Melinda.
17 July Monday – Day 7 of Hatching
I was really lucky this morning. Upon checking the nest, the chicks were busy feeding. I had waited all day yesterday for this sequence, but each time it happened, the action was partially blocked by the branches of the tree. Today, everything was almost in full view, but my video was off its tripod and I had to improvise, filming from the room by propping my video cam on a chair. Now the chicks can stand properly, rising and falling in accordance to Papa’s regurgitation moves. This locking of beaks was almost like a duel of sorts, with the chicks getting the most of Papa’s crop milk in long desperate sucks.
Sometimes, both chicks feed simultaneously on opposite sides of Papa’s beak. Today’s feeding session lasted for a good 7-10 minutes, the longest ever observed. My suspicion is that Papa just flew in and was bursting with the goodness of last night’s hunt. I could only see the back view of the chick, and noticed a new rim of yellow along its entire tail and rear region.
Feeding in earnest, neck stretched, legs extended…
Clueless about Bird Calls
I was not as lucky during lunch. The three of them had their backs towards me and no amount of whistling and noise made could get them to face my direction. Its curious that Papa seems to regard every new sound with suspicion. I’m surprised that he didn’t even seem to recognize the common call of the Golden-bellied Gerygone (Flyeater), tilting its head in puzzlement at the high pitch emission. The Gerygone is hardly the size of his babies, barely a threat at all. Also, when I first got out of the office to station myself beside the nest, Papa was once again arched in a protective stance, probably over-reacting to some distal threat.
18 July Tuesday – Day 8 of Hatching
Checked in the morning – Papa Pigeon was on duty as usual. Checked just before lunch - Papa Pigeon was still with his chicks. Meng and Melinda came at 2pm and stayed till 630pm. For close to 3 hours, from 2pm to 450pm, the chicks were mysteriously left alone in the nest with no sign of either parent. I’m not sure if Papa left the nest to go on an impromptu date with Mama, or to encourage the chicks’ independence, or to persuade them to leave the nest with him. A crow was seen on a nearby tree, but thankfully, he didn’t spot the silent chicks. Nor did a marauding cat detect the drama of the nesting going on in the tree above.
Our bright-eyed chicks getting their first lessons in independence.
I joined the fray at 430pm. Our chicks were sound asleep in the suddenly roomier nest. They didn’t seem uneasy at being left alone. At 450pm, both parents appeared out of the blue. We could hear the soft whirring of wings. Papa was the first to approach the nest, not directly but obliquely, landing on a higher branch before hopping down to greet his chicks, with Mama following close behind. Finally, we could get a family portrait, a truly heartening sight indeed with all 4 of them within the same frame. Mama then made herself comfortable in the nest with Papa taking his departure within 5 minutes. When the parents first appeared, both chicks gave out delighted cooings which all 3 of us heard.
Family Portrait: Mama takes over from Papa in the Night Shift
Description of the Chicks
Within 2 days, our nestlings have grown by leaps and bounds. Both are equi-size, at around 14-15 cm. Colours are a lot stronger now. The previously coarse black and white down with speckles of yellow has given way to a predominantly yellow colouration throughout. The nape and upper mantle still looks naked with peachy flesh showing. The shape and colour of their beaks have not changed, nor have the curious “protruding eye” look of their faces. From the front, they actually look like the cartoon bird in Road Runner with staring black eyes.
The wing feathers, especially the primaries, look sufficiently long and developed to be capable of flight. Colour wise, the wing feathers are streaked black, yellow, green and brown. Meng even caught a picture of the underwing, which has the same colouration. Essentially, the chicks don’t look anything like their parents. When they stretch themselves out, as when they are trying to reach Mama’s beak for food, they can look pretty tall and lanky.
Evidence of Solid Food in Crop Milk
Behaviour of the Chicks – Flap, Walk, Beg, Feed, Play, Preen & Sleep
Both chicks appear a lot stronger and are certainly more active and aware of their surroundings. The flapping of their wings have also begun to produce a substantial wind, occurring at a speed that is just sub take-off. We speculate that the actual fledging could take place by tomorrow or the day after. No matter how the chicks begged for food when Mama first came in, by needling her with their beaks and fidgety antics, targeting her pecker and throat area, Mama remained dry. There was an instance when Mama attempted to regurgitate but nothing came out. Both chicks could be seen jostling for their turn, and there was a point where the two babies attempted to insert their beaks simultaneously into Mama’s gape. Still, they went away empty.
Today, both chicks preferred to cluster towards the front of Papa/Mama’s breast area, two tiny bodies huddling together. The nestlings were seen actively preening themselves, and playing with their parents feathers by rubbing them with their beaks, head and body. They also played with things around them, like nibbling the twigs of their nest, nudging each other rather competitively, essentially exploring everything with their beaks, which is used here like a pseudo hand. These chicks have a very odd sleep pattern. They can doze for 15 min to ½ hour, then wake up to fidget for some 15 minutes, promptly returning to sleep again for another cycle. I wonder if they sleep in spurts at night, or in one continuous slumber. The parent is mostly awake throughout the day, sitting peacefully but alertly, only dozing at times.
19 July Wednesday – Day 9 of Hatching
Change of Shift
Meng and Melinda are truly dedicated to their craft. They stayed from 145pm to 630pm. Thanks to them, we have an idea of shift change now. At around 445pm, Mama would show up, cooing to Papa who will then vacate the nest.
For me, I only joined them close to 5pm. Its been v fulfilling to watch my chicks grow. A form of vicarious parenthood. I was most appalled when an older colleague suggested catching the birds to BBQ, said in jest of course. Still, I reeled at the thought of my ‘baobeis’ as charred meat! How tragic. Plenty of people stopped by to chat, curious at what we were photographing / filiming, and we had the privilege of opening their eyes to the avian world.
Flap, Flappity Flap
Our chicks have grown yet again. Their feathers are taking on multiple streaks of yellow, splotched with black and brown. Meng caught a v good underwing shot during their multiple flexing and flapping cycle. Curiously, for the underwing, flight feathers are well developed in the usual overlapping pattern, but the muscular portion of the wing is still largely featherless!
Meng and Melinda reported that today, flapping was more vigorous than before, with the nestlings even venturing to stand at the edge of the nest. On several occasions, they had to flap to even keep their balance, facing the danger of toppling over the nest altogether. Still, we had no fledging today.
Our patience paid off. At 620pm, 1½ hours after shift change, Mama suddenly let out a series of coos which was like a recess bell of sorts. Immediately both kids caught on, poising themselves to receive the goodness of her crop milk. One of the chicks latched on first, before his brother forced his way in, resulting in a simultaneous feed, a symphony of 3 heads and bodies gyrating to the rhythm of Mama’s contractions. The process was most endearing, the heads of the 2 babies forming a perfect heart shape. Feeding took place for over 5 minutes. Before feeding, as usual, the chicks were needling Mama to no avail.
A Love Triangle of Feeding Frenzy.
20 July Thursday – Day 10 of Hatching
A Pattern of Abandonment?
Papa pigeon was with his chicks at 9am. Strangely, at 920am Papa and the chicks kept jerking their heads to some high pitch sound that I could not hear myself. Possibly to investigate the sound, our curious parent left the nest at 925am. Today, they are expected to fledge! Then its a bitter sweet goodbye to my darlings...Anyway, when I checked at 11am, Papa was back at the nest.
Description of the Chicks
The two chicks are fine, much bigger, about 1/3 of Papa’s size. They were mobbing Papa for food as usual. When one of them extended his body to reach for Papa’s beak, a huge patch of yellow could be seen on his breast/belly area. The belly area surrounding the yellow patch is largely white. His feather cover is almost complete taking on a distinct yellow-white tinge. His head is covered in greyish down, and has become rounder somewhat although eyes still protrude. The wing feathers are beautifully arranged in rows of yellow, brown, black and white.
Meng observed that only one chick seemed to be feeding actively. At around 130pm, the more dominant chick ate everything from Papa’s crop, while his brother dozed and didn’t seem to care about food. The bigger boy was also observed to walk over to the edge of the nesting ledge, flap vigorously and actually lift off for a couple of seconds. When Mama took over at 525pm, he was the only chick to keep begging.
The dominant chick, upon closer examination, is slightly bigger than his brother and has more complete and shinier feather coverage. Its curious and amazing that one feed can make such a difference, because the night before, during the dual feeding, both heads appeared to be of the same size, sticking out of Mama’s pecker. How rich crop milk is then, to make such a difference! Mama finally relented at 6pm. Again the same pattern emerged, the dominant nestling ate everything while his brother did not even appear to be interested in feeding. The older baby even stepped on his dozing brother like a stool, in his eagerness to get at Mama’s food. He almost fell out of the nest on several occasions, tottering precariously at the edges while egging for food. His sharp claws were definitely instrumental in preventing him from falling backwards altogether. This is pretty worrying on both counts – the older one falling off, and the younger one starving to death. I really hope that dieting junior is all right and has not given up on life.
Chatting Chicks! Note dominator chick on left (green head) vs laggard chick on right (b/w head), just 2 feeds of power-packed crop milk resulted in this contrast!
Whole Indian Cherry in Crop Milk!
Meng’s amazing lenses caught the transfer of a barely digested red Indian cherry in Mama’s crop milk, with our chick gamely swallowing it! So crop milk is not necessarily milky… this is truly an eye-opener. I’m not exactly surprised that food is only partially digested as there is actually very little time elapsing between grazing/hunting and regurgitation. I’m just unsure if the regurgitation of solid food takes place when the chicks are older, or has it already been the case since Day 1 of Hatching? I suppose if the chicks of other bird species can eat whole insects, a tiny berry for a big pigeon chick should not pose any problems at all.
Yummy Indian Cherry
We speculated that our chicks would fledge in the evening, when lighting becomes poorer so that marauding crows can’t see as well, or after feeding when they have more strength to fly, or when the whole family comes together during shift change… but no, just no fledging today. The chicks are really too comfortable in their nest to move their butts! Aside from occasional wing exercises, no semblance of flight took place. But it’s a blessing nevertheless, as we get to see the chicks for one more day! Ah, I’m feeling most nostalgic and a little morose at our impending parting.
21 July Friday – Day 11 of Hatching
Our laggard chick has finally regained his appetite. For both lunch (150pm) and dinner (430pm & 515pm), he hungrily sucked Papa and Mama dry, taking the lion’s share of crop milk. His brother, not to be outdone, also imbibed the usual goodness, but was not as aggressive as before.
Difference in Plumage between Laggard & Dominant Chicks
Just one day’s feeding (2 meals) can do miracles. The dominant chick is already more lavishly plumaged than his breathen, sporting stronger colours, a greenish head tint and more verdant feather coverage. In contrast, his baby brother still has a largely black and white head. As to their wings, the bigger chick has strong brownish tones on his tertials and mantle and prominent streaks of yellow and some black on his primaries and secondaries. Previously, both chicks were about equal size. Now, the dominator has grown somewhat larger.
Uneven Development of Flight Feathers vs Body Feathers
Juxtaposing pictures of the chicks doing their wing exercises from Day 6 to 11, one can’t help but marvel at the phenomenal pace of growth of the wing feathers, specifically the over-wing and flight feathers. From mere tracts on Day 6, the primary, secondary and tertiary flight feathers appear to flourish rapidly, allowing the chicks to typically fledge between Day 10 to 12 of hatching.
Much of the energy the chick consumes is apparently targeted towards the development of these flight feathers, at the expense of all other body feathers including the under-wing and general body feathers, which remain downy at best, or even almost non-existent in the case of the naked under-wing feathers.
The reason for this uneven feather development is quite clear – flight is paramount. The ability to fly supersedes all other needs, allowing the bird to achieve a degree of independence like never before. No longer is the chick tied to the nest, imprisoned by his own immobility. More importantly, flight enables the young bird to escape various dangers more readily. It also means that the fledging can begin acquiring essential survival skills, following and learning from his parents the technique of food gathering etc.
In contrast, the body’s feathers including the head, throat, neck, back, breast and belly appear to still be downy on Day 11, functioning only to keep the chick warm. The growth observed in these body feathers is much reduced compared to that of the flight feathers. From Day 2 to 11, these down feathers become denser, taking on various colour tones, from all-yellow, to black-and-white, to finally sporting some splotches of yellow-and-green in addition to a general black-and-white hue. Not surprisingly, the under-wing itself has very sparse feathers, providing a stark contrast to the well-developed over-wing feathers.
Since the body’s feathers remain underdeveloped throughout the nesting period, they do not appear to provide sufficient warmth for the chick. As such, often times, the nestlings could be observed snuggling beneath the parent’s ample feathers to obtain additional heat. The provision of warmth is perhaps another reason for the parent’s almost continual presence at the nest.
Still No Fledging, But Lots of Encouragement from Mama
Mama came back surprisingly early today, at 230 pm, instead of the usual 5 pm. Our departing Papa flew off after hearing her distant call. At 238pm, she was seen coaxing the bigger boy to fly, perching just one branch away, about a foot apart from the nest, cooing softly at times with tail going up and down almost constantly. Big boy apparently gave out a small call and stepped out of the nest in the direction of Mama, standing expectantly on the sloping ledge, but was not convinced enough to take to the skies. However, he did attempt flight thrice, according to Meng, flapping vigorously to lift off for a couple of seconds. He then returned to the nest, but his adventures were not exactly over. Subsequently, he managed to climb up a branch to reach forever-encouraging Mama.
Younger brother is still too undeveloped to fly yet, although if he tried, he probably could. Anyhow, our patient Mama then flew in to settle down at the nest at 247pm. The pattern of standing one branch away and bobbing tail to encourage flight already started yesterday, and was caught on video by me.
Fly, baby fly, Mama is here for you!
Threat of Cawing Crows
Meng and Melinda spotted Papa perching in the vicinity at 325pm. At 328pm, Mama grew bored and flew off to join her hubby. Both were seen perching in the upper storey, perhaps keeping a lookout, perhaps staging another temporary abandonment, which has grown in frequency as a prompt to the chicks that their time has come to leave the nest too. A couple of crows seemed to have caught on to the PNGP nesting. At 4pm, two of them baddies were seen flying overhead and hopping through the trees, searching. They could possibly smell the scent of the young ones, but thankfully the winds were confusing and the nest sufficiently well concealed in the leafy shadows. Meng observed Papa mobbing the crows and successfully chasing them away. Meng thinks that the crows do not yet know the exact location of the nest, but seem to have sensed its presence as they hung around for an uncomfortably long time, for nearly 20 minutes.
22 July Saturday – Day 12 of Hatching
Boo hoo, my babies flew the coop without me witnessing! I was out on a NSS trek (MacRitchie to Upper Pierce) instead of watching them take their first flight. What a bad parent I’ve been! Vicarious parenthood does have its woes. Melinda and Meng returned to the nest at around 1130am, and already it was empty. They both heard the chicks chirping high above in the canopy, but could not get a visual on them. I really hope that they are fine and not victims to the marauding crows.
I’m feeling most wistful that they have finally fledged and I shall never see them again. Yesterday, I guess I had already said my goodbyes, knowing that this could well happen. We had all planned to come in the afternoon to continue our observations, as we did not think that our chicks would fledge in the morning, but apparently, birds, as well as time and tide, waiteth for no man. Now the nest is bare, and I’m staring at it, all alone. Time indeed to bring the curtains down. Adios my chicks, and here’s wishing them all the very best…Ciao.
Kudos to Meng & Melinda Chan
I am really glad that we (Melinda, Meng & I) could do this joint documentation together. They have been next to amazing - coming for 7 afternoons for 4 to 6 hour shoots each time since 15 July (Saturday). That's more than 24 hours of observations! Meng's camera is a 500mm Canon EOS1 with 1.4xTC, a bazooka that produces v good quality shots. I'm really pleased with the excellent pictures!
Plus I'm pretty happy with the footage I took, key events of everything except the actual fledging. However, the quality of the digital video, after downloading into my computer, is less than desirable. And the file for just one tape is a gargantuan 20.5 GB, and I have 2 tapes with 2 hours worth of footage to edit!!! After 6 whole months, I've finally finished editing the video.