Crimson Sunbird: Adult and juvenile male plumage

on 10th August 2008


The male Crimson Sunbird (Aethopyga siparaja) is eye-catching because of its prominent crimson head, back, throat and upper breast.

In a juvenile male bird, the crimson is not apparent until later when individual crimson feathers develop as the bird moults from a juvenal to a breeding plumage. As individual breeding feathers develop, the redness appears in scattered patches as seen in the image above (right)

However, an adult male during the non-breeding period sheds most of his crimson feathers on his head and breast, taking on an eclipse dress. When the next breeding season comes, he will develop his colourful plumage once again.

So is the bird above (right) a juvenile male or a male in eclipse dress? Or is he a young adult in eclipse dress?

Choo Teik Ju
August 2008

Cheke, R. A., Mann, C. F. & Allen, R. (2001). Sunbirds: A guide to the sunbirds, flowerpeckers, spiderhunters and sugarbirds of the world. New Haven & London: Yale University Press.

This post is a cooperative effort between and BESG to bring the study of bird behaviour through photography to a wider audience.

If you like this post please tap on the Like button at the left bottom of page. Any views and opinions expressed in this article are solely those of the authors/contributors, and are not endorsed by the Lee Kong Chian Natural History Museum (LKCNHM, NUS) or its affiliated institutions. Readers are encouraged to use their discretion before making any decisions or judgements based on the information presented.

YC Wee

Dr Wee played a significant role as a green advocate in Singapore through his extensive involvement in various organizations and committees: as Secretary and Chairman for the Malayan Nature Society (Singapore Branch), and with the Nature Society (Singapore) as founding President (1978-1995). He has also served in the Nature Reserve Board (1987-1989), Nature Reserves Committee (1990-1996), National Council on the Environment/Singapore Environment Council (1992-1996), Work-Group on Nature Conservation (1992) and Inter-Varsity Council on the Environment (1995-1997). He is Patron of the Singapore Gardening Society and was appointed Honorary Museum Associate of the Lee Kong Chian Natural History Museum (LKCNHM) in 2012. In 2005, Dr Wee started the Bird Ecology Study Group. With more than 6,000 entries, the website has become a valuable resource consulted by students, birdwatchers and researchers locally and internationally. The views and opinions expressed in this article are his own, and do not represent those of LKCNHM, the National University of Singapore or its affiliated institutions.

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5 Responses

  1. Hi Yeow Chin,

    While I cannot say if the Crimson Sunbird adopts an eclipse plumage elsewhere, that does not seem the case in Singapore. Here, we see full plumaged males throughout the year, whether they are breeding or not.

    Perhaps this may be due to our weather being more or less consistent throughout the year, allowing for a longer breeding season. There appears to be, for example, evidence of nesting between December – September, for the Olive-backed Sunbird.

    The bird in the right photo should be considered a immature that is slowly moulting into the adult male plumage. This seems to be confirmed by the orange gape, which is an indication of an immature/juvenile.

  2. Thinking about this further, I realise that in most cases that I can recall, a Crimson Sunbird showing blotches of red is normally an immature in moult to adulthood.

    However, there have been instances where a Crimson Sunbird has only shown red on the throat and have also been assumed to be immature males. However, I cannot recall if these birds had pale gapes that would confirm their immaturity. Perhaps it would be worthwhile for everyone to look out for such birds and perhaps obtain photos to confirm if they are indeed immatures or could they be males in eclipse!

  3. I notice that there is a difference in the undertail-pattern. While the juvenile/immature has a blackish tail with white tips to the outer two tail feathers and a white outer web to the outermost tail feathers, while the adult male seems to have a uniform brown tail.

    if this character is true than a mottled male with a adult-tail pattern would be in an eclips plumage while a mottled male with a patterned tail is a moulting immature. A complete adult male with a patterned tail would be an immature then.

    I have no time to check this om photo’s, but it would be inetresting

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