Thanks again to the NYT crossword, we now know that the answer to 16 Down: Hawaiian goose is Nene!

The official bird of the State of Hawaiʻi, the Nēnē is exclusively found in the wild of the islands of Maui, Kauaʻi and Hawaiʻi. The Nēnē gets its Hawaiian name from its soft call. Its strong toes have much reduced webbing, an adaptation to the lava flows on which it breeds. It mates on land unlike most other wildfowl. This is the world's rarest goose.