2nd ccplim's suggestion for Eco-Lake. There around the water's edge you can find many birds among the vegetation, including white breasted kingfisher, white breasted waterhen, Ashy Tailorbirds, blue-tailed bee eaters, Asian Brown Flycatcher, magpie robin, white throated fantails etc. You just need to be patient, keep your eyes and ears open for their calls and you can find them. Best timing is around 7-10am in the mornings.
You can also try out the Symphony Lake (the one with the performance stage built on it) where you can find Lesser whistling ducks, kingfishers, bitterns and also the nearby Heliconia Walk which is a favourite with many nature shooters in CS due to the many sunbirds that like to frolic among the heliconia stalks.