The Sumatran Drongo lives in humid forests on Sumatra and catches insects by sallying from a perch. This account places the former Mentawai subspecies with Hair-crested Drongo.
Adults are black with a deep ultramarine-blue gloss, a red eye and a nearly square-ended tail. Females are smaller; juvenile plumage is undescribed in the account.
It uses submontane and lower-montane forest and catches insects in aerial sallies; it also hops up trunks to take ants.
An extinction-risk assessment has not been added yet.