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Crimson Sunbird: Post-juvenal Moult

on 18th May 2016

SunbirdC-preen [RichardLim]

“The male Crimson Sunbird (Aethopyga siparaja) above looks like it is just completing its first post-juvenal moult. The crimson plumage has yet to be uniformly developed as seen HERE.

“A newly hatched male Crimson Sunbird is naked. The first feathers to develop are the downs, soft and fluffy. Next come the juvenal feathers, the first true contour feathers. As the juvenal feathers grow (juvenal moult), they push out the downs, which may drop off or temporarily attached to the developing juvenal feathers.

“In the case of a juvenile male Crimson Sunbird, there would be no trace of crimson feathers. These crimson feathers appear in isolated patches around the head, back, throat and upper breast only when the bird develops its breeding plumage – see HERE.

SunbirdC-preen [RichardLim]

“Moulting: The upper tail coverts (feathers covering the base of flight and tail feathers) and the outermost tail feathers are still growing. You can still make out the growth bands on the tail feathers (below). One dark and one light band makes it a day of feather growth, so you can actually count how many days the bird will take to replace one feather.

SunbirdC-preen [RichardLim]

“The reddish edge to the tip of the upper tail coverts is quite interesting and was never mentioned before by authors of published text (above). Robinson (1927) described the upper tail coverts as metallic violet. I have no opportunity to examine a male Crimson Sunbird, so have not seen this coloration before.

“The oil gland (aka preen gland or uropygial gland), the white pimple-like structure below the yellow rump feathers can be seen clearly in the above image. Birds use the oil from the preen gland to maintain the suppleness of the feathers and prevent them from getting brittle (works like a conditioner). The oil was previously thought to be the waterproof agent for the feathers but now it seems that it is only indirectly so. The actual waterproofing was done by making sure that the barbs and barbules are well interlocked with each other, providing a tight surface on the feather which is not only crucial for providing lift but also to prevent water from wetting the feathers.”

Richard Lim (images) & Wang Luan Keng (text)
Singapore
12th February 2016

(NOTE: Wang Luan Keng is a field ornithologist. She runs The Nature Workshop that undertakes nature education and outreach programmes to increase awareness of biodiversity and nature conservation.)

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.

Other posts by YC Wee

4 Responses

  1. Also, take note: “The reddish edge to the tip of the upper tail coverts is quite interesting and was never mentioned before by authors of published text…” This is seldom described and rarely seen…

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