We have a pair of Yellow-vented Bulbuls Pycnonotus goiavier nesting in the neighbourhood. I was alerted to them this morning (14th May 2023) as I heard adults making warning calls when a neighbourhood cat approached too close to the nesting site. I chased off the cat and the birds were then able to continue feeding their young.
Although the birds allowed me to watch their nest at close range, I decided to use the car as a hide to minimise any disturbance, and to avoid others in the neighbourhood from recognising there was a nest present.
I watched continually from 7.30 to 8.30am to observe feeding behaviour and food items brought to nestlings. After that I had to abandon watching as we are currently having a heat wave and the car became uncomfortable to stay in.
The nest is located in an urban garden, placed in a Cordyline terminalis bush at approximately 0.75 meters above the ground. The nest is well hidden in the centre of the bush and it is not possible to see the juveniles unless I ask for access to the neighbour’s home and look directly from above (I have not done this). I am uncertain as to the maturity of the chicks, but from prey items brought to the nest, they appear to be fairly developed.
Adults often come together (at the same time) with prey or very close to each other. One adult would wait for the other to finish feeding before entering the nest. They often leave the nest area together. There was no attempt to have one adult stay and protect the nest unless a threat was observed (see below). Once a large portion of Papaya fruit was offered but it appeared to be too bulky for the young to take. It was then removed, broken down and reoffered as a smaller portion. On one occasion a large Dragonfly was brought to the nest with the wings removed. On four occasions, when insect prey was brought, both adults arrived, although only one had prey.
There were 17 feeding episodes over the 60 minutes. Mean feeding frequency was every 3.8 minutes with a range of 1-9 minutes and a mode of 1 minute. 6 food items were fruit (3 Ficus fruit, possibly Ficus benjamina, and 3 Papaya portions). 7 food items were winged insects (all were different insect species; one was an orange Dragonfly). 1 item was a small frog. 3 food items were not seen. The composite image shows some of the food items brought to nestlings. Notice that in a number of images, the crest of the birds is erect due to the presence of perceived threats.
I did not see any faecal sac removal during this period. I am also observing another Yellow-vented Bulbul this week at a forest location, where the chicks are very young. At that nest I once saw an adult consume a faecal sac. Although the literature states that faecal sacs are carried away from the nest, I wonder if the sacs of very young birds, that may be nutrient rich, are consumed.
On three occasions in the one hour of observation, the adult birds chased away other pairs of Yellow-vented Bulbuls that had strayed too close to their nesting site; this was at 8-10 meters from the nest site. Other birds like Eurasian Tree Sparrows Passer montanus, Common Mynas Acridotheres tristis, Asian Glossy Starlings Aplonis panayensis and Brown-throated Sunbirds Anthreptes malacensis were ignored. On one occasion a Common Treeshrew Tupaia glis was in the area, about 8-10 meters away on the road, and the birds immediately flew to its location and monitored its movements from the safety of electrical wires. In our garden, nesting has significantly reduced in the past few years due to the daily/continual presence of Common Treeshrews. All these perceived-threat-events interrupted feeding of the young.
Dato’ Dr Amar-Singh HSS
Ipoh, Perak, Malaysia
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