The Straw-necked Ibis is a large waterbird. The upper body is a distinctive glossy dark green-purple with white underparts. During the breeding season, the Straw-necked Ibis grows yellow straw-like plumes on the upper chest and neck, making them easily distinguishable from other ibises.
Large flocks of these birds can be seen flying in a V formation when the birds fly to grassy paddocks to feed before returning to their nesting colony on islands in Port Phillip Bay, generally from July to December. They are nomadic, with movements influenced by rainfall, moving seasonally between areas alone or in groups. By consuming many insects and their larvae, especially locusts, they help farmers to be more productive.