Streak Throated Swallows roosting

While driving from Ranthambhore towards Jaipur, I noticed this beautiful roosting of what looks like Streak Throated Swallows (Petrochelidon fluvicola) in a nearby farm.
In the left hand side of the image is a small canal/stream with a bridge. The Swallows have built many many mud nests under the bridge.

I have never seen Swallows roosting on the ground like this, and in such healthy numbers (to our modern eyes, I am sure the numbers were larger only 15 years ago).

Since the farm was fenced with dried thorn scrubs, I couldn't get a closer shot. My Nikon 80-400 maxed out to give me this image.
(Going closer would also have been difficult considering how shy these birds are).

A closer crop of the same image.

(I didn't straighten the horizon)

Nice . it is typical of swallows and swifts to roost in large numbers but as you said they usually seen on wires, walls and stone structures. were they collecting mud for nest building?
TFS
Roopak

Perhaps. There were mud nesting colonies nearby.

Lovely. Great to see this. On what date was it photographed?