An immature male White-rumped Shama?

posted in: Morphology-Develop., Species | 1

Dato’ Dr Amar-Singh HSS wrote of his encounter in the Kledang-Sayong Forest Reserve in Ipoh, Perak, Malaysia on 19th April 2010: “When I arrived at the Forest Reserve, this bird was on the forest floor foraging. Managed to watch from the car as a hide from a close vantage point. Was low light in early morning but did not want to disturb with a flash (a shy bird and extensively ‘hunted’).

“I had assumed it was female but closer inspection of the pictures shows that the upper mantle, nape and throat are all a deeper purple-blue than the grey/black expected (left). The Copsychus malabaricus mallopercnus subspecies female is reported as ‘cap to back is grey, all with a slight sheen …’ (Wells 2007).

“The underparts are not rich chestnut enough for an adult male. The fact that I could capture the purple-blue in low light and without flash suggest it is rather ‘prominent’. Wonder if this is a juvenile male in transition to adulthood. One of the prey I managed to see was a forest ant (with wings) (left bottom)”

According to Dr David R Wells: “This highlights a real problem with the taxonomy of WR Shama. There is great disagreement and confusion about subspecies in SE Asia, based largely on how different males are from females. One of the central problems is whether immature males pass through a plumage stage of looking like adult female before they reach true adult male condition, or whether they moult directly from juvenile to full adult plumage, with no intermediate stage.

“Those who have kept captive males from the fledgling stage could probably answer this question but, of course, they are not generally the kind of people who record their observations.

“What you show here I guess might be an intermediate-stage male (dull wings, proportionately rather short tail) but I cannot prove it. Its white rather than rufous upper legs would identify it as subspecies interpositus/macrurus rather than mallopercnus, suggesting these merge over a wider geographical zone than generally believed.”

One Response

  1. Lee Chiu San

    There are supposed to be about 18 sub-species of White-rumped Shamas. The two most common in the trade in Singapore come from the Pahang/Johor region and the Penang/Langkawi/South Thailand region. These birds are quite easy to identify visually. The former is larger, more stout, and has a shorter, stiff tail.

    Before the bird-flu scare which resulted in the Agri-Food and Veterinary Authority of Singapore clamping down on the import of wild-caught birds, recently-fledged young birds were very commonly sold.

    I can state without a doubt that as far as these two sub-species are concerned, the young males moult directly from juvenile to adult plumage and do not pass through an intermediate stage where they might resemble females.

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