Considerable individual variation in size and plumage renders determination of subspecies difficult, leading to various treatments. Here, possible races chinensis (much of mainland range from India E to E China) and javanica (Malay Peninsula, Greater Sundas) included within nominate owing to overlap in measurements, but may well be valid; proposed race maldiva (Maldive Is) also subsumed within nominate, leucocephalus (Car Nicobar) within insularis, and variabilis (Sulawesi) in leucomelana. Four subspecies recognized.
Birds from Sangihe and Talaud Is (NE of Sulawesi) normally included in nominate race, but may be closer to other Sulawesi forms; further study needed#R.
Food and feeding
Status and conservation
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