Black-naped Oriole – immature

posted in: Morphology-Develop. | 1

“The ripe papayas in the neighbourhood are a magnet for Black-naped Orioles (Oriolus chinensis maculatus) and this self-feeding, immature bird was present today at the same time as an adult. Note the immature features:

OrioleBN-imm [AmarSingh]

1. Poorly developed black on tail (above).
2. Incomplete/developing black nape and face mask.
3. The black streaks on the breast (below).
4. The iris is red-brown, rather than fully blood red.

OrioleBN-imm [AmarSingh]
OrioleBN-imm [AmarSingh]

“Of interest is the bluish facial skin, not described in literature. Looking through my older images of juveniles, it is present in some images/birds. I suspect the black mask will obscure this in adults. The bill is like the adult colour, although I have seen immature birds of similar development that still have partially black bills.

OrioleBN-imm [AmarSingh]

“There is still limited data on how juveniles and immatures change. I went through all my past images of young birds and did this composite of 9 different birds based on age/appearance (see above). The top 3 are recently fledged birds. The middle three juveniles that were able to feed self, and the bottom 2 on the left immature birds with one adult on the bottom right. Some observations:

1. The iris changes from grey-brown, to brown, then brown-red to blood-red.
2. The bill is much more variable. Although generally black in juveniles it can have a pink hue; sometimes more pink in younger birds and darker black in older birds. A more mature bird (8th in sequence) can have residual black in bill while a less mature bird can have an all pink bill.
3. Similarly the black nape and eye mask can develop earlier or later.
4. Some have a more prominent hooked bill.”

Dato’ Dr Amar-Singh HSS
Amar-Singh HSS (Dato’ Dr)
Ipoh, Perak, Malaysia
15th February 2018

Location: Ipoh, Perak, Malaysia
Habitat: Urban environment

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One Response

  1. in the last picture, does that apply to the male or female sex of the change?

    0

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