|By Alfred Chia|
I wrote previously on my FB and Singapore Bird Group FB on the nesting of the Olive-backed Sunbird along the corridor of my house, see: https://www.facebook.com/540928362/posts/10158109695448363/?d=n &
After the mysterious disappearance of the entire nest, I requested for information and feedback from readers of any similar experiences, since many will have experiences with nesting of the Olive-backed Sunbirds, it being a species that is very adaptable and will nest freely in close proximity to humans and its environs. Several readers responded and I am thankful to them.
Out of eleven readers who responded, one (众生云云) had the same post-breeding experience as me in having a whole nest disappear without any trace (no debris was found) while another (MeiLin Khoo) had a pre-breeding disappearance, also without trace.
Another (VirgoSG) had two nests disappearing with debris being left behind but it is unknown if these were pre or post-breeding disappearances.
Clara Tan responded that hers was most probably a case of predation by a Yellow-vented Bulbul (Pycnonotus goiavier), which had been observed eyeing the nest even during the nest-building phase. It subsequently tried to prey on the chick but was unsuccessful in the first instance. However, the entire nest, together with a week-old chick, went missing soon enough. There was also not a trace of debris. Alan Owyong also contributed by sharing that he had also seen a Yellow-vented Bulbul harassing a sunbird while it was nest-building while Weijie Liao witnessed a nest being destroyed by a House Crow (Corvus splendens).Puran Kaur also had a pair of Olive-backed Sunbirds nesting in her balcony. After the chicks fledged, the nest was however left intact with no action whatsoever from the sunbirds for more than two weeks.
Predation by a cat was shared by Ong PL (through Tracy Heng). Such predation is possible if the nest is low and within reach of the cat, even if it is on a tree. But predation by a cat would almost always result in a nest being destroyed entirely, with remnants of it being strewn around it.
Basanthi Seetoh, who have had the honour of having more than 30 nests in her balcony over 15 years shared her experiences that used nests maybe re-use after some repairs and touch-up by the sunbird (documented) or they may strip off some parts of the old nest to build another new nest nearby.
Yet another observation was made by Lim Khoon Hin of an uncompleted nest being strip apart by the sunbirds after it was hung back by the observer’s helper when it dropped due to strong winds. Every bit of debris that fell on the ground was cleared by both the male & female sunbird!
Finally, Chen Eddie shares an intriguing encounter of a sunbird stealing nesting material from another sunbird’s nest.
In summary, it remains a mystery how an entire sunbird’s nest can disappear without any trace. The distinct probability that it could have been predated and taken away whole by a predator such as a Yellow-vented Bulbul cannot be ruled out. It is also noted that several different actions may happen to the nest after the chicks are fledged: re-used, dismantling of bits of nest for possible use elsewhere or left as it is.
The various contributions by readers of their personal experiences are valuable and serves to add to our knowledge of a species of bird that may appear common to most of us but for which there are still gaps to be learned. So keep a lookout for future nesting of Olive-backed Sunbirds. You may well observe something new & intriguing!
Thanks are due to Alan Owyong, Basanthi Seetoh, Chen Eddie, Clara Tan, Lim Khoon Hin, MeiLin Khoo, Ong PL, Puran Kaur, Tracy Heng, VirgoSG, Weijie Liao & 众生云云.
The Varied Diet of the Yellow-vented Bulbul Chicks. By Seng Alvin.
The ubiquitous Yellow-vented Bulbul Pycnonotus goiavier has to be the most common bird in our urban greenery. Its bubbly call is a welcome sound in our parks and gardens. If you listen carefully, they have different calls and alarms for different situations.
With two hungry chicks to feed, the parent bulbuls were kept busy throughout the day
I was lucky to come across a nesting pair at Pasir Ris Park this June and decided to document the food that the parents brought back to feed the chicks, and it was very varied.
Insects formed the main source of proteins for the growing chicks. Wasps from a nearby nest, a green grasshopper and a spider showed the variety of the feed.
My monitoring started on the 17th. I spent one to two hours each day between 8.00 am and 10 am photographing the the feeding process. Both chicks successfully fledged on the 22nd after a week of feeding.
Happy and well fed chicks about to fledge on the 22nd June.
For the first three days, the parents brought back soft and small insects that can be easily digested. Spiders and caterpillars were also a good source of proteins for the growing chicks. In the later stage, berries and figs supplemented larger insects like grasshoppers.
Squashed figs and berries will form the main diet of these frugivorous species when they grow up.
In first part of the day, the parents will usually feed the chicks with insects. As the day progressed, they would start bringing back figs and berries to the chicks, for desserts? As there was a wasp’s nest nearby, they took full advantage of this ready source of rich protein insects. I wonder how do they neutralise the venom if any inside these wasps?
Sharing a fat caterpillar.
From my observations, their diet is not just varied but well balanced for the chicks to grow up as fast as possible to begin another generation.
The above article by Wing Chong, past chairman of the Bird Group, was first published in Lianhe Zaobao on 12 Feb 2016. Below is a translation of the article.
‘It rained for more than three hours that Sunday afternoon. The sky was still gloomy when the rain finally stopped. It was breezeless and humid and very uncomfortable to stay indoors. So, I picked up my camera and decided to go for a walk at the nearby Japanese Garden.
The fresher, post-rain air lifted my spirits. Just as I entered the gardens, I was drawn to movement in the Ixola (Ixola coccinea) bush. A Yellow-vented Bulbul was busy feeding around the bush. I stopped to take a second look. She would first perch motionlessly on the ixola, before suddenly springing vertically upwards, catching the insect in midair, and making a beautiful twist before dropping back to the bush. These motions were repeated many times in seemingly erratic directions, and reminded me of a graceful ballet dancer. I suppose I was a little late to the show, as this performance didn’t last long.
Happy that I had managed to click a few shots, I proceeded towards the lotus pond to check out the lotus flowers. As I was passing a small pond I was attracted by another set of actions. On a Lagerstromia speciose, two Yellow-vented Bulbuls were also busy feeding. I sat on a rock to watch the show with the grayish sky as the backdrop. The rhythm was a bit erratic but the movements were quite similar. The bulbuls would first perch motionless on the tree, looking into the air, like dancer waiting for their musical cue. The insect that flew up was like a music note that triggers the dancers’ action. Suddenly one of them would take off followed by the other. Sometimes both of them might take off almost simultaneously. The beautiful moves comprised of take offs, twists, mid-air freezes and graceful landings. It looked just like a ballet duet except each star had his own routine, without coordination with the other. The show went on and on for 15 minutes.
As the sky got darker the dance came to an end. The dancers were tidying up their ‘dance costume’ on the tree top when I decided to leave them. As I turn, I realized that I was not the only audience of the show. An elderly couple stood right behind me. Judging from the expressions on their faces I presumed they had also enjoyed the show. We exchanged smiles as I walked by.’