This species is endemic to the Indian subcontinent. The extent of white on the belly varies. Birds in the northern part of their range average less white. Easily confused with highly variable Ashy Drongo which has a much longer, usually more deeply forked tail and bright red eyes. Immature Black Drongo may also have a pale belly, but with dark barring. Three subspecies are recognized. This is the widespread nominate race. Two other subspecies are confined to Sri Lanka. Canon PowerShot SX50 HS
References:
Rasmussen, PC & Anderton, JC (2005). Birds of South Asia. The Ripley Guide. Washington DC and Barcelona: Smithsonian Institution and Lynx Edicions.
Rocamora, G. & Yeatman-Berthelot, D. (2016). White-bellied Drongo (Dicrurus caerulescens). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/60588 on 13 May 2016).