Whio / Blue duck
Hymenolaimus malacorhynchos
Threatened - Nationally Vulnerable
Fast, fearless and river-loving, the whio, or blue duck, is one of Aotearoa’s most iconic and endangered waterfowl. Found only in clean, fast-flowing mountain rivers, whio are a living indicator of freshwater health. Their unique whistle-like call and striking blue-grey feathers make them unmistakable – if you’re lucky enough to spot one.
Quick Facts:
- Whio are strong swimmers, using their large webbed feet to navigate white-water rapids.
- Named for their distinctive call, which sounds like a soft whistle: “whio!”
- Along the rivers, whio live in territorial pairs, while lone males may try to carve out their own space. Once a pair stakes a territory, it’s often theirs for life.
- Whio form lifelong, monogamous pairs and fiercely defend their river territories. Nests are hidden close to the river – in caves, riverbank holes, or under ferns and fallen trees – and the female lays 3–8 pale eggs, incubated for about 5 weeks.
- Both parents guard and feed their ducklings for 70–80 days until fledging. Once the adults start their post-breeding moult, the grown ducklings are gradually pushed out to make way for the next generation.
- Their presence signals healthy, rivers and streams – the more breeding pairs of blue duck the healthier the river.
- Honoured on New Zealand’s $10 note – a symbol of their cultural and ecological significance.
Protecting whio means protecting our wild rivers – keeping them clean, cold and safe from predators like stoats. Where there’s whio, there’s hope.
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