Grey-rumped Treeswift nesting record at Mandai

The Grey-rumped Treeswift (Hemiprocne longipennis) is one of the two species of treeswift recorded in Singapore. The other, the Whiskered Treeswift is a very rare resident that is seldom seen, with only one recent record at Upper Peirce Reservoir in 2011.

The Grey-rumped Treeswift on the other hand is a more common resident in Singapore. They can be found regularly at the Singapore Botanical Gardens, Macritchie Reservoir and recently at Bishan Park. In April/May 2011, there was a nesting record in Mandai which I had a chance to document.

Grey-rumped Treeswift
Both the male and the female take turns to incubate the egg. The nest of the egg is rather small and can only fit in one adult and one egg.

Grey-rumped Treeswift
The male of the species has orange red/chestnut coloured ear coverts that this female lack. Both have an attractive crest.

Grey-rumped Treeswift
Like it’s close cousins the true swifts, the treeswift diet consist mainly of insects hunted from the air. However unlike its more airborne cousins, it start its hunt from a perch where it sit and scan the surrounding vigilantly for prey nearby. Once a suitable prey has been sighted, it perform short sallies from its perch. The preys which are usually flying insects are usually taken on the wing.

Grey-rumped Treeswift
One of the surprise of this nesting was the discovery of a juvenile bird that landed very close to the nest and adults. It is not known whether it is the offspring of the adult pair or the offspring of another pair nearby. What we do know is that there were at one time only 2 adults present of opposite sex.

Grey-rumped Treeswift
A closer look at the juvenile. You can see clearly the difference in appearance compared to the adult. It has scaly marks on its chest area and spots on it’s face and crest. Also, proportionally the eyes are bigger than in the adult.

Grey-rumped Treeswift
The juvenile is seen here flying, just like an adult would, but proportionally the bird looks different as well.

Grey-rumped Treeswift
Here the juvenile is turning it’s head mid air to search for food. This turn suggest that it is ready to hunt for it’s own food.

Grey-rumped Treeswift
Having said that, while on the perch, the juvenile was seen waiting for the adult to feed it. I did not personally witness the actual feeding, but friends monitoring the site managed to capture the moment soon after this on the same perch.1


Now, this video is rather perplexing. Is the juvenile looking for it’s own food, scanning the sky for insects, or is it looking for it’s parent to feed it? I guess it could be both. In the end, it let out a yawn. Growing up is hard work.

Ultimately, the nesting failed for the egg that we encountered. If my memory serves me, the eggshells were seen at the bottom of the nest. Perhaps predation by other animals or birds. Such is nature.

The area in Mandai is no longer accessible to the public as it is now a restricted area. Perhaps treeswifts continue their existence there. Hopefully they continue to thrive.

References:
1. Adult feeding juvenile treeswift photographed by Jason Cho

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