Oriental Reed Warbler – prey and calls

on 27th December 2021

I was able to get out today, further afield and watched a number of migratory Oriental Reed Warblers (Acrocephalus orientalis), common at this wetland site. Many birds were actively feeding ‘together’ today as there were swarms of midges (green coloured non-biting midges that look mosquito-like in the family Chironomidae).

Besides the Oriental Reed Warblers, other birds feeding on the Chironomidae include Pied Trillers (Lalage nigra), Common Ioras (Aegithina tiphia horizoptera), Yellow-vented Bulbuls (Pycnonotus goiavier analis), Paddyfield Pipits (Anthus rufulus malayensis), flocks of Daurian Starling/Purple-backed Starlings (Agropsar sturninus), Sand Martins, Barn Swallows (Hirundo rustica) and Pacific Swallows (Hirundo tahitica javanica).

Some birds were taking the Chironomidae as winged prey, especially the Swallows but the Oriental Reed Warblers were predominately gleaning them from foliage and stems of plants; often reaching upwards or downwards. The activity was fast and they allowed me to watch closely; akin to birds feeding on alate ants or termites. Prey was taken from a height of 1 to 2 meters, as the bird worked its way up and down the bushes. Rarely prey was snatched from the air (Post 2).

None of the Chironomidaewere branch swiped, as they are rather small prey. I once spotted a daddy long legs spider (Pholcidae, cellar spider) taken (above). In the past I have seen Oriental Reed Warblers consume, by gleaning from foliage, three different types of winged Hymenoptera, one of which looked like a Wasp.

The birds were also fairly vocal, once active feeding had subsided (~9.30am). Calls during migration have been well described by Wells 2007 (using his work here). Above is a waveform and sonogram of 4 types of calls I heard; the differences can be better appreciated in the upper waveform. An extended calling (in the same order) of the 4 types of calls are in the SoundCloud link:

Calls are generally loud and easily audible; these were recorded with a shotgun mike and camera and then edited. Calls in group 1 are a single discreet ‘tak’; occasionally these may be repeated as 2 calls rapidly together. Calls in group 1 are of a lower amplitude in the waveform but surprisingly of the same frequency as group 1 in the waveform. They sound like the churring “trrrrk” calls. Group 4 has the rolling “trrrak” calls. Group 3 sound like “kirr” (see HBW 2018).


Amar-Singh HSS (Dato’ Dr)

Ipoh, Perak, Malaysia


Location: Malim Nawar Wetlands, Perak, Malaysia

Habitat: Extensive ex-tin mining area with pond/lakes, wetlands, fish farming

Date: 2nd January 2019

Equipment: Nikon D500 SLR with Tamron SP 150-600mm f/5-6.3 Di VC USD, handheld




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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