A rare penguin rescued after being found in an emaciated condition has been released back into the wild to find romance.

The young adult yellow eyed penguin (hoiho) nearly doubled its weight since arriving at Massey University’s wildlife ward three weeks ago.

Wildlife vet Roberto Aguilar said the penguin was found in a poor condition on the Wellington coast.

The bird was initially cared for by the Native Bird Rescue Wellington Trust and was then moved to Massey’s specialist wildlife facility.

“It was a young adult and whether it had swum or followed a wrong current, it was very thin and extremely dehydrated. It was doing what we call hock-sitting, where it is unable to stand up properly,” Aguilar said.

“We started feeding it, making sure it got enough energy and it started coming around pretty fast.

“It has gone from 3.5kg to 5.3kg and it’s gaining about 100g a day. It now looks pudgy, which is good because it’s the fat store that protects them from the environment.”

Although it was not known whether the penguin was male or female, it was sent back to the Otago Peninsula on the weekend so it would be able to find a mate.

Department of Conservation programme manager David Agnew said there were about 470 breeding pairs in the South Island, with the rest of the 6000-7000 population on Stewart and the sub-Antarctic islands.