common muntjac (Muntiacus muntjak)

free-ranging at the zoo. There are many many muntjac being used as cage-fillers so I reckon the ones I saw roaming about uncaged were escapees rather than actual wild ones using the zoo as living space.

For everything else at the zoo, see my review here: http://www.zoochat.com/254/visit-assam-state-zoo-guwahati-10-a-358287/