Sunbird’s plumage

posted in: Feathers-maintenance, Sunbirds | 1

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Sunbirds exhibit sexual dimorphism. The males are usually colourful with their dazzling iridescent plumages while the females are generally drab looking and lack any striking patterns.

The male of the Crimson Sunbird (Aethopyga siparaja) is a spectacular looking bird with its bright red mantle (left top). Although a smallish bird, whenever it appears, it immediately draws attention to its presence. Similarly, the Brown-throated Sunbird (Anthreptes malacensis) is just as spectacular and colourful, especially when the light strikes it at the right direction (left bottom). The females of both species cannot boast about their looks. Both are ordinary looking, their plumages dull olive-green or yellow.

But wait, there is the so-called male eclipse phase for certain species. The plumage of this intermediate phase is not as spectacular as the breeding plumage but it is distinctly different from the female plumage.

Take the Olive-backed Sunbird (Cinnyris jugularis) as an example. The male (below top) is not as spectacular as the other two, but compared to the female (below middle), is just as attractive. The male eclipse is at the bottom of the three images below.

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The presence of male eclipse phases can be terribly confusing to newcomers but experienced birders generally take them for granted. Now how does the male eclipse comes about? Through moulting of course. After the breeding season the male moults its colourful plumage and take on a less attractive eclipse dress. Once the next breeding season comes, he will again take on his colourful plumage.

There have been much research on the African sunbird species and it is known that there are three groups in terms of moulting regimes of male sunbirds.

1. The chick sheds its juvenal plumage and takes on an intermediate immature plumage, to be followed by a breeding plumage once the breeding season sets in. There is no eclipse phase.

2. There is no immature and eclipse plumages. The bird moults from juvenal to breeding plumage and from one breeding plumage to another.

3. There is no intermediate immature plumage. The bird moults from juvenal to breeding plumage but it has an eclipse phase between one breeding season to the other.

As far as our regional sunbirds are concerned, we only know that there is an eclipse phase in certain species. I am not sure whether there are any observations on intermediate immature plumage of our species.

Can any experienced birders or ornithologists comment on the above?

YC Wee
Singapore
April 2007
(Images by YC except Brown-throated Sunbird by Johnny Wee.)

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  1. […] pas pour les pauvres tats-Uniens. This entry was … Mail (will not be published) (required) …Bird Ecology Study Group Sunbird’s plumageThe bird moults from juvenal to breeding plumage and from one breeding plumage to another. … The […]

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