ML620334385

Observation details

Not sure about species, there were 6-7 individuals moving as a flock. At first I thought perhaps Australian swiftlet which would also be very rare in the area but later local birders from Darwin mentioned the occurrence of Himalayan types in the region the previous year and suggested it could be it. Later other observer suggested it could be this species because it has a relatively deeply notched tail, and some forms do show indistinct barring on the under parts. So I place it here waiting for more input. They vocalized quite frequently but I was not able to record.