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White-winged Tern: Breeding, non-breeding and transitional plumages

on 7th July 2008

Jonathan has been monitoring the White-winged Tern (Chlidonias leucopterus) at Kranji since 2005.

In that early period when he was new to birds, he was rather puzzled by the “chocolate chip” tern he photographed and had difficulty getting it identified (below left). He now knows that it is a White-winged dressed in a transitional plumage.

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The White-winged, also known as White-winged Black Tern, breeds in Siberia. It winters south, moving down the Malay Peninsula to Singapore and beyond to as far as Australia.

In Singapore, it is possible to see the bird both in its non-breeding (above right) and breeding plumages (below). The image below shows the breeding plumage, although “not quite though, judging from the white flecks on the head” – according to our bird specialist R Subaraj. Similarly, the “chocolate chip” bird at the top shows early transitional stage, as only some black feathers have developed.

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Adds Subaraj: “White-winged Terns usually start arriving as migrants in September. They occur in numbers, particularly during passage, in coastal and offshore areas (and freshwater too). Numbers have declined over the years due to a reduction in foraging areas around our coastlines; such as the original Sg. Serangoon estuary where pig swill would empty out of the Sg Serangoon Kecil from the pig farms and this would attract hundreds of terns.

“Northbound return passage is often late in April/May and during that latter period is when you may have more birds in transitional or near-breeding plumage, as they moult in preparation for their return to their breeding grounds in the north.”

Input and images by Dr Jonathan Cheah Weng Kwong

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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