The annual coin for 2021 features the extinct Auckland Island Merganser Mergus australis. It is part of a range of coins and stamps that celebrate New Zealand's taonga, culture, heritage, arts, stories and people. This annual coin series, focusing on extinct animals, highlights New Zealand’s unique environment, biodiversity and conservation issues.
The sexes of the Auckland Island merganser were similar to each other, but males were larger and had an obvious and elongated crest. The head and neck were dark brown, the entire upper body dark grey, and the breast and abdomen dull greyish-brown. The upper wings were slate grey, and the lower wing coverts were darker and banded white. The middle secondary flight feathers were white on the outer web and black on the inner web and tips, with the primary flight feathers and inner secondaries tending blackish. The eyes were dark brown, and the upper bill black but with its cutting edge and the lower mandible yellowish-orange; the legs and feet were orange. Immature birds were darker versions of the adults. Ducklings were dark brown-black above with yellowish-white underparts. Their bill, legs and feet were dark olive-brown.