Information from Wikipedia
Square-tailed Drongo-Cuckoo (Surniculus lugubris including brachyurus, musschenbroeki. This has white bars on vent and outer undertail, tail only notched with slightly flared tips. In flight a white wing-stripe is visible from below. This is found in South East Asia and is a summer visitor to the Himalayas from Kashmir to eastern Bangladesh. The calls are series of piercing sharp whistles rising in pitch but shrill and choppily delivered.