If you look at the undertail pattern, Indian is supposed to have two thick black bands: one at the end (terminal) and one towards the end (subterminal) of the tail (mentioned in
Why This Cuckoo Is Lesser Cuckoo - Shanghai Birding 上海观鸟 and
Indian Cuckoo ID Basics - Shanghai Birding 上海观鸟).
You can see examples of Indian Cuckoo's undertail pattern here:
Another difficult bird to get close to. But he has got a song that is very distinct. It goes something like this " One more bottle " " One more bottle " Must be Dr. Manjeet's favourite drinking partner in the bush....
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Juvenile. Common winter visitor/passage migrant to Singapore. Settings: 1458mm ISO400 1/100s 0EV.
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Each day in my practice is a new day...sadness is there but emence laughter too...being half-loony i do meet some full lonny patients too..:D...like to-day..pefect day with sun out..tho it had rained all night heavely but morning was...
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I don't think there would be such a size difference among fully-feathered birds, but I don't know. Ascribing the species here by size alone would be tricky, anyway.
Lesser also appears to be the expected un-Common
Cuculus cuckoo, but better wait for expert confirmation. As far as I can tell, Lesser Cuckoo would be an uncommon migrant, while Indian Cuckoo would be an uncommon resident. Whatever it turns out to be, congratulations on your find and a very interesting bird.
EDIT: I should suppose a yellow gape means juvenile (unless it's moulting into immature plumage, maybe).