I would say that this is an Oriental/Horsefield's rather than Common.
Not much of the underpart barring is showing (only the sides of the breast), and although this looks a little narrow there is a tendancy for the barring to be slightly narrower on the sides of the breast in most adult cuculus cuckoos. I spent some time at the British Museum last year looking at specimens of these species (as part of the review of the first record of Common Cuckooon Po Toi) and i was stuck by the differences in the throat. In Common the throat patch is paler (less blue) and has a lower border which is usually not well defined. In Horsefields/Oriental the throat patch is darker, slightly bluer and typically has a very defined lower border.
How useful is iris colour?
I've seen this quoted as a feature for the ID of Indian cuckoo (which supposedly has a dark iris).
Looking through the pictures on OB, it get the impression that adult Common has a yellow iris, similar to the colour of the eye ring. Iris seems to be a bit more variable in Oriental - some are dark (brownish), while others are paler (straw-colour) but still seem to be darker than on Common.
I don't know whether iris colour may be related to season or sex, or maybe individual variation. D
oes anyone know if this is a useful feature to look for?
Incidentally, the iris on the Ping Long bird looks dark, which could support the ID as Oriental/Horsfield's Author: lpaul Time: 14/04/2010 14:18
Iris colour varies extensively with age, generally getting paler and yellower with age. Photos of the Po Toi Common Cuckoo (an adult) show an orange-brown iris. Author: kmike Time: 14/04/2010 18:49
Many thanks for all these comments.
I would add that the breast band did not look too narrow in the field, so I'll put it down as Horsfield's/Himalayan.
Cheers
Mike Author: ajohn Time: 15/04/2010 09:30
Thanks Paul for clarifying the situation with iris colour. I thought maybe it was age-related, as pictures of juvenile Common Cuckoo on OB do all show a dark iris.
It seemed strange to me, though, that all pictures of adult Common showed a yellow iris, but those on Oriental all seemed darker (except perhaps this one http://orientalbirdimages.org/se ... _ID=&pagesize=1). Perhaps just coincidence?
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