The search for an elusive Fiordland crested penguin in Milford Sound has revealed the birds are thriving.

The Tawaki breed in remote and inaccessible areas, making it difficult to observe and study.

However, 60 breeding pairs have been monitored with GPS data loggers, as well as pressure and temperature sensors.

It wasn't all good news though, as researchers also witnessed the devastating effects of stoats on the penguins.

Tawaki are the third rarest penguin species world-wide.

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