The emperor penguin who was found thousands of kilometres from home at a Kapiti Coast beach is set to be released into the Southern Ocean to fend for itself, when it regathers its strength.

The Antarctic bird, dubbed Happy Feet, has been in surgery at Wellington Zoo after it became seriously ill from eating sand and sticks on Peka Peka beach.

The penguin advisory committee this morning decided the preferred option would be to release Happy Feet into the Southern Ocean, rather than transporting it to Antarctica.

This is the northern edge of the known range of juvenile emperor penguins.

"The reason for not returning the penguin directly to Antarctica is that emperor penguins of this age are usually found north of Antarctica on pack ice and in the open ocean" DOC biodiversity officer Peter Simpson said.

The penguin will not be released until it is deemed well enough to have a reasonable chance of survival.

It will stay at Wellington Zoo in the meantime.

X-rays today revealed that Happy Feet the emperor penguin is making excellent progress.

Wellington Zoo veterinary manager Lisa Argilla said x-rays taken this morning showed the penguin had passed about half the sand in his system.

She expected he would be able to pass the rest of the sand naturally and at this stage another endoscopy would not be necessary.

"He's doing better. He's a lot stronger and he's moving around a lot," Argilla said.

Happy Feet has come around from a general anesthetic and has been returned to his cold room of ice.

Happy Feet was spotted on Peka Peka Beach last Monday and transported to the zoo for surgery on Friday.

RETURNING PENGUIN 'ILLEGAL'

The Antarctic Treaty, signed by 46 nations and enshrined in New Zealand law, stipulates that no living bird is allowed to be taken into Antarctica.

Though the emperor penguin is native to the continent, taking him back there would breach the treaty's protocols on environmental protection because of the risk of disease, Antarctica New Zealand science manager Ed Butler says.

Micro-organisms picked up on the penguin's 4000-kilometre swim to New Zealand or while on our shores could cause Happy Feet to become sick months down the track.

"Even if we screened Happy Feet, we still couldn't be sure that he wouldn't be carrying something that would turn up in blisters and sores in six months' time and kill all his mates," Butler said.

Agriculture and Forestry Ministry research shows a suspected virus that struck a colony of adelie penguins in Antarctica in 1972 killed 65 per cent of baby penguins in the colony of thousands.

"There are 150,000 breeding pairs in some colonies, and 65 per cent of that is a big number," Butler said. "That's a lot of dead penguins for one penguin."

- © Fairfax NZ News