The Glossy Ibis nests colonially in trees, often with herons. It is also gregarious when feeding in marshy wetlands; it preys on fish, frogs and other water creatures, as well as occasionally on insects.

This species is 55–65 centimetres (22–26 in) long with an 88–105 centimetres (35–41 in) wingspan. Breeding adults have reddish-brown bodies and shiny bottle-green wings. Non-breeders and juveniles have duller bodies. This species has a brownish bill, dark facial skin bordered above and below in blue-gray (non-breeding) to cobalt blue (breeding), and red-brown legs. Unlike herons, ibises fly with necks outstretched, their flight being graceful and often in V-formation.

Sounds made by this rather quiet ibis include a variety of croaks and grunts, including a hoarse grrrr made when breeding.