Yellow-vented Bulbuls’ display after rain

posted in: Miscellaneous | 12

Lena Chow wrote on 6th July 2009: “Some 3 years back, I observed Yellow-vented Bulbuls (Pycnonotus goiavier) darting in and out of the trees of Aljunied Park after a heavy rain. At that time, I had only a little pocketcam, and could not provide any images as the action was going on at canopy level, and about 30m away from my bedroom window where I was watching it.

“Last year, I upgraded to a prosumer with an 18x zoom lens, but did not manage to see such behaviour again – until today. I had just returned from work at about 7.15pm, and there had been a refreshing downpour in the afternoon. I looked out at the trees to relax, and I saw that familiar dance again – I whipped out my camera, and took a few shots. Unfortunately, as the light was fading, and the birds were diving in and out of the treetops, these are the best shots I can manage. Not sure if there have been any new insights to this behaviour since 2006.”

“I might just add that there were again about a dozen birds that were flying in and out of the canopy of a single mature tree, and I watched the action till about 7.30pm or so when darkness set in” adds Lena.

After three years we are still no better off in understanding such behaviour. It is unfortunate that experienced birdwatchers simply do not observe these bulbuls as they are common. Yet the behaviour of most of our common birds are relatively unknown.

12 Responses

  1. I was just wondering what was going on just about two weeks ago when we had those thunderstorms in the later afternoon.

    I have a captive YVB in my house. It struck a window and is no longer able to fly…so I have since kept it as a pet. I am used to its calls now and it seems it also is a bit more chirpy after the afternoon rains.

    Back to that afternoon, I heard YVB calls near my apartment and thought it was coming from our pet. But the calls were far too frequent and sounded like it was coming from more than one bird. Only then did i realise that our pet was also joining in the musical interlude after the rains.

    I tried to hunt down the source of the calls and it was strongest from the toilet, I thought maybe another bird flew into the toilet.

    Finally I found the source of all the singing. There were at least 6 pairs of YVB perched on a palm tree adjacent to the apartment. The tree top was at my window level. As you had described, the birds were darting in and out of the tree top and singing their hearts out. I found it odd as these birds are usually pretty territorial and you seldom see more than two pairs at any one location. To see 6 pairs in a single tree is really something unusual.

  2. I forgot to mention that this happened after heavy rains and it was just about sunset.

  3. As you had mentioned Lena, this is something that is not frequently observed. I myself have not seen it before until two weeks ago.

    I guess the timing of the rain must be correct and it happens only at sunset.

    Could also be a seasonal thing. I noticed that the breeding season has just passed. Hormonal levels must have ebbed by now and the territorial instinct subsided. This display seems to me a fitting end to successful breeding season.

    There are many bulbuls living around my condo. I always keep an eye out for birds when I take my children walking in the evenings. Yet I have never seen such a loud and energetic display by so many bulbuls all on the same small tree.

  4. Thanks for sharing your experience, Jeremy. Fascinating.

  5. Do you see them ‘displaying’? Another possibility is the appearance of winged ants after the rain. The YVB are having a good time feasting on them on air.

  6. K C Tsang

    Yes, after rain, there would be a lot of winged ants flying up from gardens, and parks, I have witness that before with the Bulbuls suspended in air pecking at the ants… As usual did not have my camera with me …. !!!!

  7. Thanks Jeremy for the corroborative account. The same behaviour I observed 3 years back was, if I recall correctly, in the late afternoon. Gan & KC, thanks too for your comments. I did not observe any winged ants that the bulbuls could well be feasting on; but then again it was getting dark, and the birds were rather far away.

    Assuming though that the bulbuls were feasting on winged ants, could it then be that the dozen or so bulbuls were banding together as a species to monopolise the feast? As observed in the previous occasion as well as this one, there are no other birds around at this time. I shall certainly keep a lookout for insects next time I see this behaviour again – hopefully soon!

  8. It could well be a termite hatch and the bulbuls were feasting on the winged termites. See… http://besgroup.talfrynature.com/2006/01/12/termite-hatch/

  9. With regards to my observation, there were no flying termites at the time of observation. I was barely 3m away from the group as I sneaked up to the window. The were mostly calling out loudly (but not displaying). Each pair sort of took turns pretending to evacuate the tree only to fly straight back to the crown of the tree.

  10. After this afternoon’s downpour, I observed the same display as above, at the same tree at about 7.00pm. This time I looked out for flying insects with binoculars, but could not see any.

    Thinking that this particular tree could be too far to see any insects clearly, I took a quick walk around the neighbourhood. I saw bulbuls perched on top of mango trees in my neighbours’ gardens – some were flying between trees, and some were also doing the fly out – about turn – fly back in routine. There were no flying insects about that I could see.

    Was anyone also observing bulbuls this evening?

  11. Thanks Lena. Mystery deepens.

  12. […] out from a tree canopy after the rain way back in June 2006. Three years later in July 2009 she posted another account, this time with photographic evidence, of the same […]

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