Olive-backed Sunbird: Compliment of the season and pectoral tuft

In May 2017, I had the opportunity to document a male Olive-backed Sunbird (Cinnyris jugularis) stealing nectar from flowers of the ornamental banana plant, Musa ornata.

SunbirdOB-m pectoral turft [wyc]

All my attention was then focused on how the sunbird probed its sharp bill through the lower portion of the flowers to get at the nectar. After all, its bill is too short to reach the nectar when probing through the top of the flower, unlike that of the spiderhunter.

Seven months later when I was screening my video clips to produce a video-greeting for Christmas and the New Year, I came across the earlier clip. Only when I was working on the clip to include a musical message did I notice a patch of orange under its wings when the sunbird was moving around the flowers (above). Slowing down the relevant portions helped to further focus attention on the patch. It was only then that I realised that what I was seeing was the pectoral tuft (below).

The male Olive-backed Sunbird has a pair of pectoral tuft that is prominently displayed during courtship. It is claimed that they only develop during the breeding season LINK.

When the male sunbird is not courting, the pair of pectoral tufts is hidden under the wings. The rapid movements of the wings may expose the orange tufts and this was captured by my video above.

This shows the value of video over photographic documentation in the study of bird behaviour.

Taking pectoral tufts documentation one step further, it would be interesting to find out whether these pectoral tufts are really absent during non-breeding periods. The fact that these orange patches are well hidden and usually not noticed unless they are exposed during courtship may contribute to such belief.

YC Wee
Singapore
24th December 2017

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