Too hot for Adélie penguin to return home

It turns out Wellington can be too hot - at least for an Antarctic penguin.

The scheduled release of an Adélie penguin on Wellington's south coast on Friday was abandoned when the penguin began to overheat.

The Adélie penguin - a species usually found exclusively in Antarctica - was found on Petone Beach earlier this month.

Since then, it has been in the care of Wellington Zoo, where a full health check was carried out, including testing for the deadly bird flu virus, which returned a negative result.

The zoo confirmed on Friday afternoon that the penguin's attempted release was foiled by the weather, and a certain reluctance from the bird to fly (swim) the coop.

"She stepped out of her crate, paddled in the shallows, but then decided to head back up onto the beach," the zoo said.

"We gave her space and time to make her choice, watching quietly from a distance."

But as the heat in the sun grew, the penguin began showing signs of heat stress, and the decision was made to return her to her ice-pack lined captivity.

The zoo said it will be re-evaluating her release alongside the Department of Conservation. No new date for a reattempt has been set.

"For now she will be staying at the zoo a little bit longer. She won't be visible to visitors at this stage."

Wellington Zoo vet Kirsten Anderson said it was unfortunate that they could not interview the penguin, so could only speculate about why she didn't want to leave.

It was possible that being a colony species, alone in unfamiliar territory, presented too much risk, she said.

"In Antarctica there would be huge group of them that would look out for each other as they were entering the water.

"The ocean is home, but it is also potentially a dangerous place - that's where predators, like orca, might be able to grab them.

"Potentially she was just feeling a little bit nervous or wary just by herself."