A rare Fiordland penguin has been nursed back to health after travelling 5000km to Western Australia.

Photo: Perth Zoo

'Roxy' the Fiordland penguin spent months swimming thousands of kilometres to Australia.

Perth Zoo, where she has been sent for rehabilitation, said a Parks and Wildlife officer found her on a beach in the town of Denmark, near Albany. She was malnourished and had a foot injury.

Zoo staff said the vet team cared for the wild penguin, described as an "extremely friendly and rare patient".

On Tuesday, she was sent to Sydney by plane to join other New Zealand penguins at Taronga Zoo, which has three other captive Fiordland penguins and isthe only zoo in the world with Fiordland penguins.

Fiordland crested penguins (tawaki) are one of the rarest of New Zealand's mainland penguins. The population is estimated at 2500 to 3000 breeding pairs, the Department of Conservation says.