Yellow-vented Bulbul nesting in a Staghorn Fern

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“Something for both my birder and fern friends …. A pair of yellow-vented bulbuls (Pycnonotus goiavier) built a nest in the nest fronds of a staghorn fern (Platycerium willinckii) which was conveniently right in front of my window and thereby gave me an opportunity to observe the nesting and successful fledging of one chick. This was actually the second nesting in the same fern. In an earlier nesting in January, two eggs were laid and hatched, and the chicks cared for by the parents for about 12 days but the eventual fate of the chicks is unknown. By the second nesting in March, I was prepared and was able to video-record the incubation, brooding and fledging of the bulbul chick.

Adult brooding chicks about 9 days after hatching (January 2017)
Adult brooding chicks about 9 days after hatching (January 2017)

“The nest was constructed of dried leaves and twigs, with inside dimensions of 5 cm depth and 6 cm diameter. Conveniently enough, the nest fit perfectly inside the nest fronds of the fern and was well-hidden from any predators.

Nest was 6 cm inner diameter and 5 cm depth, hidden inside nest fronds of Willinckii staghorn (March 2017)
Nest was 6 cm inner diameter and 5 cm depth, hidden inside nest fronds of Willinckii staghorn (March 2017)

“One out of the two eggs hatched on day 13. Hatching started while the adult was away from the nest, but the adult returned immediately when the chick started to emerge from the shell. The yellow-vented bulbul is a fastidious housekeeper and egg shell fragments were removed even before the chick fully emerged from the shell.

Hatching of yellow-vented bulbul from Shih Tung Ngiam on Vimeo.

“Both parents were observed feeding the chick during the entire brooding period, but as the sexes could not be distinguished, I was unable to tell how feeding and brooding duties were shared between the parents. As described in Wee (2009) PDF, the adult birds usually did not fly directly to the nest, but would perch on another nearby fern and apparently scan the area before flying to the nest. Diet of the chick included berries, flowers and insects. In some instances, the chick would refuse or be unable to swallow food brought to it, in which case the adult would simply ate the food. The YVB’s were fastidious housekeepers and would consistently swallow fecal sacs excreted by the chick. They were regularly observed pecking at the nest, presumably to remove debris or to eat any insects that were present.

“Both adults were frequently observed perched or even strutting along a fence near the nest. This was presumably a territorial display or decoy behaviour as this behaviour was only observed when the nest was active. The video below shows an adult YVB feigning injury by pretending to have a broken wing and rolling on the ground (00:03 – 00:22) after I approached the nest to adjust the recording equipment. The bulbul then flew to the fence and staged a territorial display (00:25 – 00:50) strutting up and down a section of the fence. The YVB staged this display even when no humans were near the nest and it was quite likely that the displays were directed against other birds (mynahs, spotted doves) or threats in the area.

Yellow-vented bulbul feigning injury from Shih Tung Ngiam on Vimeo.

Yellow-vented bulbul (Pycnonotus goiavier) pretending to be injured so as to divert attention away from its hatchling when a perceived threat approaches its nest

Fledging of yellow-vented bulbul from Shih Tung Ngiam on Vimeo.

First flight of yellow-vented bulbul chick born in nest inside a staghorm fern (Platycerium willickii)

“The chick first started spreading its wings while inside the nest but then sat down again and the adult returned to feed the chick and brood it for a few minutes after which the parent left. Bird calls were heard on the video and I assume those were calls of the parents who were in a nearby tree. The chick eventually stood up and started flapping its wings until it finally flew out of the nest. Neither parents nor the fledgling were observed returning to the nest but two YVB’s are still seen in my garden.”

Ngiam Shih Tung
Singapore
6th April 2017

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