There is still hope of a storybook ending for a much-loved emperor penguin named Happy Feet.
The theory he pecked off a transmitter attached to his tail feathers is a feasible explanation as to why he suddenly dropped off the radar, a Havelock North company that designed the device has said.
Sirtrack had been following Happy Feet's progress since he slid from Niwa research vessel Tangaroa into the Southern Ocean at the start of the month, but had received no signal from the 3-year-old penguin since September 9.
Happy Feet had travelled 115 kilometres after being released near Campbell Island.
Many feared the worst for Happy Feet, but Wellington Zoo vet Lisa Argilla, who was his main carer on the journey to freedom, felt sure he had simply removed the irritating device himself.
"I think Happy Feet, who was definitely Mr Stroppy Feet towards the end of his journey, was determined to get the offending object off and I believe he succeeded," Ms Argilla wrote on her blog.
"I saw him paying a lot of attention to preening the area where the transmitter was attached."
Sirtrack wildlife telemetry consultant Kevin Lay said it was likely that Happy Feet was one of a small number of penguins who would not tolerate such a device.
"If he was as stroppy as they say he was, he could well have got it off.
"Most penguins couldn't care less, but there are about two to three per cent who are annoyed by it. Usually we would remove the device in that situation.
"The most likely explanation is that either he pulled it off or it has come off."
The penguin was found on the Kapiti Coast after eating sticks and sand.
He received two months of specialist care and underwent multiple operations before he was allowed to return to the wild.
After he was released Happy Feet followed a normal pattern for a penguin, Mr Lay said.
"He's got an awesome chance to live and I think he's taken it."