Happy Feet "gobbled down" the sticks that were found in its stomach because it had never seen them before and probably thought they were fish, experts say.
The emperor penguin was found on Peka Peka Beach, north of Wellington, last Monday, more than 3000km from its Antarctic home.
It was taken to Wellington Zoo for treatment on Friday after being seen eating sand. Yesterday vets removed about half of the sticks and sand in Happy Feet's system.
Wellington Zoo spokeswoman Kate Baker said the 27kg bird would be given laxatives to help it pass the remainder over the next few days.
Associate Professor John Cockrem, a penguin expert at Massey University, said he believed the bird had eaten the sticks out of curiosity and confusion.
"When I saw it on the beach, it was gobbling down sand and sticks and just whatever was in reach.
It had only ever been on ice or on snow, so sticks were something it had never seen before. It maybe thought the sticks were little bits of fish sitting on the ice," he said.
Happy Feet was still in a critical condition last night but Ms Baker said the penguin was getting better each day.
Zoo staff were still waiting for DNA results to determine the bird's sex, she said, and an advisory group would meet tomorrow to discuss what will happen to Happy Feet.
Millionaire businessman Gareth Morgan has offered to take the bird home on a Russian icebreaker ship making an expedition to the Ross Sea in February.
However, Professor Cockrem, who is in Happy Feet's advisory group, said the safest option was to release the penguin back into sub-Antarctic waters south of New Zealand so it could make its own way back to Antarctica.
"I don't think taking it straight back to Antarctica is appropriate because of the diseases it's carrying, which are a potential problem for the other Antarctic birds."
He said if Happy Feet swam itself back, the diseases would naturally be removed from its system. However, he could not guarantee the bird would make it back to its home alive.
"It might be a good idea to put a tracking device on it, so people can follow where it's got to." He would prefer for the bird to be released rather than put into an enclosure.