Male and male eclipse Olive-backed Sunbirds taking nectar from Musa ornate flowers

The male Olive-backed Sunbird (Cinnyris jugularis) in breeding plumage is distinctive in its iridescent blue-back forehead, throat and breast with a reddish band below. The non-breeding male, or eclipse male, appears less attractive in its yellow underside and a blue-black streak running down the centre of the throat

In the video clip below, an eclipse male is seen probing its sharp bill into the base of the petals of the male flowers of the Ornamental Banana (Musa ornate) to steal nectar. As it withdraws its bill from the flower, its long tongue can be seen extending beyond the tip before being withdrawn back into the bill (above). The sunbird is deemed stealing because it does not probe the flower from the top where the stamens are. It bill will thus not be covered with pollen and in its next visit to female flowers, will not effect pollination. That no pollination takes place is confirmed when only small, seedless fruits develop. Only when the female flowers are artificially pollinated will fruits be large and packed with seeds – see HERE and HERE.

The second video clip below shows both eclipse and breeding male Olive-backed Sunbirds visiting the female flowers of the Ornamental Banana. At the beginning of the clip, an eclipse male tries hard to probe the female flowers from above. Unable to reach the nectar source below because of its short bill, it flies off to return later and ultimately probing into the base of the flower via an opening created by an earlier sunbird.

Breeding males have no problem probing their sharp bills through the ring of petals to get at the nectar. Unlike the eclipse males, they do not try probing the flowers from above. I presume this is because they are older and have more experience with these flowers.

YC Wee
Singapore
5th July 2018

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