|I had wanted to get better images and observations of this sunbird and a bird watching colleague suggested this site (bit of a drive) for better lighting. I was able to find at least 3 pairs and heard more in the undergrowth as I walked the site. I managed to get one pair to accept me slowly over three hours of my presence to allow for better images. Some observations summarised:
Much of their feeding is checking tree foliage and bushes for small animal prey, presumably insects. I did not see any spiders taken but I did see spider web on the birds.
Nectar feeding in the mangrove forest is limited to the flowers of the mangrove trees. Wells (2007) had noted nectar feeding on Bruguiera flowers, a small genus of six mangrove species. Wells noted B. gymnorhiza and B. hainesii as identified nectar sources. I can confirm that Bruguiera sexangula (commonly called the Upriver Orange Mangrove, or locally Tumu Putih) is also used as a nectar source. Of these 6 mangrove species, B. gymnorhiza, B. sexangula, B. exaristata, B. hainesii have larger flowers and are considered to be bird-pollinated (B. exaristata is native to New Guinea and northern Australia). These large mangrove flowers have explosive release of pollen, which happens when birds probe the flowers.
I was privileged to observe some courtship activity. Initially when I saw males chasing other males, I assumed it was territorial. But I subsequently saw a female singing out raptly with her body kept rigidly straight, pointed upwards or downwards and flitting from branch to branch. I saw three males in attendance, looking excited and following her and chasing each other. The impression I got was that she was indicating by song that she is ready to breed and the males were vying for her attention.
The mangrove habitat at this and other sites continues to suffer significant destruction from encroaching agricultural activities and logging. These birds are considered locally as near-threatened bordering on vulnerable (Wells 2007).
I saw the females mainly together with males, except on one occasion alone. The females always remind me of Little Spiderhunters Arachnothera longirostra with a grey head and yellow breast. Although the tail is said to be black, in good light it looks more like a dark blue-black (seen in a number of birds). The under-tail feathers have large white tips. The yellow on the belly was richer & more pronounced in some birds, perhaps a breeding feature. The head has a mottled appearance on close up due to the darker feather bases (Wells 2007).