Brown-throated Sunbird – moulting

on 4th March 2022

Post 1. Unsure of the sex of this juvenile.

I have not been paying enough attention to two Brown-throated Sunbirds (Anthreptes malacensis malacensis) in the garden who have been enjoying the nectar from our Callistemon spp (Bottlebrush tree) and Albizia spp (Mimosa Tree).

Post 2.

Some images of the self-feeding male, moulting. This could be a juvenile/immature moulting into adult plumage, but there hardly any ‘convincing’ gape present and bare parts look adult.

Post 3.

There is no data on eclipse plumage phase for adults but it may be possible. I am uncertain why the tail in this bird is so short. The calls the bird made were like those of an adult. Note that juvenile bills are usually lighter with some pale pink/orange.

Post 4. A composite image of 4 different birds showing the transition from juvenile to adult plumage.

Post 5. This is a juvenile female. Note the lighter, orange lower, proximal mandible and gape.

I cannot be sure of the sex of the first juvenile in Post 1. After reviewing all my observations of immatures moulting, the first metallic plumage to appear are usually some feathers in the face/neck giving the appearance of a moustachial steak, and a few feathers in the scalp. This is followed by changes at the nape. Mantel changes are late.

Post 6. This is a male in strong light with a blood-red iris.

Post 7. A sonogram of the calls of this male.

The above is the sonogram of the calls of the male, common calls made by this species and usually repeated in varying frequency – can be rapid in sequence (every second) or 3-5 seconds apart. Handbook of the Birds of the World Alive (2020) describes these 2-3 note calls as the ‘song’ and translates them as “sweet-sweet”, or “swit-swit-sweet”. The sonogram is fascinating in its structure, showing far more complexity to the ‘song’ than what we hear with our ears.


Amar-Singh HSS (Dato’ Dr) – Ipoh, Perak, Malaysia

Habitat: Urban environment

Date: 25th July 2020

Equipment: Equipment: Nikon D500 SLR with Nikon AF-S Nikkor 500mm f/5.6E PF ED VR, handheld with Rode VideoMic Pro Plus Shotgun Microphone



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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