This pre-monsoon is natural activity. Thunder clouds as well as spells of rain on different days is indicative of the Monsoon knocking the doors of Delhi.
In the morning of 10th June 2017, I heard the sound of the pied crested cuckoo and I sighted the same in flight . It just landed up the canopy of a tall tree. After a few seconds it flew again and went away as being chased by a house crow. For the last so many days I am hearing their sound and even able to see either perching them on the top of the tree or in flight.