Common Myna – juvenile with head moult

06 Jun 2013   in Morphology-Develop. 3 Comments »
Contributed by Dato’ Dr Amar-Singh HSS

“I am posting an adult [Common Myna (Acridotheres tristis tristis)] who had juveniles in attendance. The adult was well groomed (above left) and one juvenile’s plumage seemed appropriate (below), but the other juvenile seemed to have an early onset of the adult head moult (above right and bottom). I have yet to see a juvenile with loss of head feather so early as in above right that the back of the head is also affected.

“There have been different opinions as to the cause of this loss of head feather in adults. The majority opinion is that it is a form of moulting. I hold the opinion that it is some form of disease (my medical background and it is quite grotesque).

“Now seeing a juvenile with it so early I wonder if there is a genetic component to this problem (despite the visible adult parent being OK at this point in time).”

Dato’ Dr Amar-Singh HSS
Ipoh City, Perak, Malaysia
12th May 2013




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    3 Responses to "Common Myna – juvenile with head moult"

    1. DAISY O'NEILL says:

      Hi Amar,

      From what I got told by bird veteran up north, it seems it is a kind of fungal infection attack whereby, the gradual total loss of feathers around the nape and neck renders the bird looking like those we see in those days of domestic chickens devoid of neck feathers the Chinese called, ‘ Holland chickens’.

      When I first encountered one in my residential area, I thought I was looking at a different species of Mynas!

      Cheers!

      daisy

    2. Thanks Daisy. I support the infection ‘theory’ but many think this is just a moult.

      One recent comment on these images (when posted on OBI) from Hans Peeters:
      “I am no expert on myna molts and diseases, but there are good reasons to support the molting hypothesis. If you look at this picture, you can see that the pattern of baldness is symmetrical (a parasite infestation would likely be irregular). Furthermore, the bird is molting in other parts of the body, too (for example, I see a half-grown new tail feather as well as a secondary). The other bird in the picture hasn’t yet started the head and body molt, although the primaries are clearly new (such partial molts are common in passerines).

      Keeping an open mind as more observations allow us to make a firm decision.
      Amar

    3. K Sim says:

      Interesting article and this observation always intrigues me. I have seen some of these adult birds with heads completely bald. And I thought it had to be disease of some sorts. If it moulting, the feather drop and replacement would have been concurrent rather than complete baldness. Interestingly. Other Myna species had no such issues. My daughter once said. Since they always find food at our hawker Centres, they must be eating too much MSG causing hair loss. lol.

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