I was alerted to the nesting of a pair of Olive-backed Sunbirds (Cinnyris jugularis, formerly Nectarinia jugularis) by KC Tsang in April 2006. The nest was attached to a frond of a palm by a well-trodden path in a popular park. The elongated, flash-shaped nest was attached to the inside face of the frond and the opening was thus facing the palm stem and away from the road.
The nest was just above eye level. Yet, nearly all passersby failed to notice it. The nest looked like a bunch of dead leaves hanging on to the palm frond. I myself failed to notice it whenever I walked passed it in the evenings.
By May 2006 the nesting ended as the nest was empty for days after. Olive-backed Sunbirds usually lay one to three eggs but only one chick fledges. The empty nest deteriorated and on examination it contained one unfertilized egg. So I presume one chick must have fledged.
In March 2007 another nest was built on the same palm but attached to a different frond. Whenever I passed the spot and remembered the presence of the nest, I took a casual look and there was always a beak projecting from the opening (below left). Then in early April I noticed the frond where the nest was attached was drying out and its sheath was about to be detached from the stem. Thinking that nesting was completed, I moved close and suddenly a bird flew out. The nest was still active.
The next evening I made it a point to check on the nest. The frond was gone. An older frond that was about to fall off was also missing. On looking at the ground below, I saw two old fronds lying side by side. One frond had the nest still attached (left, arrow). There were no eggs inside. There was no sign of any eggs lying around nearby either.
Did the old fronds got detached by themselves or were they physically removed? My guess is that they were pulled down and left on the ground as they were lying side by side. It is possible that the maintenance crew did it, removing old and unsightly fronds from the palm. And not knowing(?) that there was an active nest attached.
I have since been told that such things happen all the time. Plants are regularly trimmed, nest and all. Now why can’t these people be made aware of such things – to leave active nests alone when pruning, etc?
Another puzzle is the absence of any eggs inside the nest. Were the eggs removed out of curiosity? And then thrown away?
Obviously the birds made a wrong choice by choosing a frond to build their nest that would not last the entire period of their nesting. Now how would the birds to know of such things?
Input and images by YC.