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Ciconia nigra
Diet
Amphibians, small fish and insects, taken by wading slowly in shallow water
Range
Breeds across Europe and the Palearctic to the Pacific; winters in tropical Africa and Asia
Clutch size
2–5 greyish-white eggs
Incubation period
32–38 days
Size
95–100cm
Wingspan
145–155cm
Weight
About 3kg
The black stork is a large, shy and wary bird, 95 to 100cm long with a 145 to 155cm wingspan and a weight of about 3kg. The adult has mainly black plumage with white underparts, long red legs and a long pointed red bill, brown eyes and bare red skin around them. It is a widespread but uncommon species (Wikipedia, general species account).
It breeds in scattered places across Europe and east across the Palearctic to the Pacific, and is migratory, wintering in tropical Africa and Asia, though some populations are sedentary. It feeds on amphibians, small fish and insects. The female lays two to five eggs, incubated by both sexes for 32 to 38 days, and the young fledge after 60 to 71 days. The sources read give nothing specific to Bhutan.