Vedanthangal Bird Sanctuary near Chengalpattu, 70 kms from Chennai is very well maintained.
Neat pathways, no litter anywhere, convenient viewing galleries,cordial and helpful staff.
The oldest bird sanctuary in India !
They are closed on national holidays.
While there is a bus service from Chengalpattu, timings may not be convenient to the planned visitor.
Better option would be to hire a cab or auto rickshaw from Chengalpattu.
You will not be disappointed at all ! A feast !