These storks can often be observed feeding in aggregations with other wading birds, such as lesser adjutant (Leptoptilos javanicus) and egrets (Ardeidae) (7). The bulk of the diet at Sungai Burong, Malaysia, is apparently large mudskippers (Periophthalmus), although the species has also been recorded feeding on small fish, snakes and frogs (2) (7).
The milky stork breeds colonially, often in multi-species aggregations that may sometimes contain up to several hundred milky stork nests, although more commonly 10 to 20 (7). Breeding appears to peak during the dry season, in January and February in Cambodia and in July and August in Indonesia (2) (7). Dry-season breeding probably coincides with maximum fish stocks, following the rainy season (7). Nests are typically built between 6 and 12 metres up large trees (2), and are fairly bulky structures of sticks, lined with fresh leafy twigs (7). Clutches generally contain one to four eggs, which are thought to be incubated for 27 to 30 days. Young are able to leave the nest and fly poorly at six to seven weeks, and can fly well by eight weeks, but are still dependent on food from their parents (7). Both male and female take part in incubating the eggs and caring for and feeding the young until they are ready to leave the nest (8).