The young emperor penguin, nicknamed Happy Feet, is to undergo another procedure at Wellington Zoo on Monday.
The rare visitor from Antarctica was taken to the zoo's hospital on Friday from Peka Peka beach on Kapiti Coast, where it had been spotted a few days earlier.[image:2331:third:right]
It had become increasingly distressed and had been eating sticks and sand, in place of the snow it would normally consume.
Vets have been able to flush out some of the contents of its stomach - but say more sand, and possibly some driftwood, remains.
The penguin will undergo an endoscopy which involves a camera being inserted into its stomach on Monday morning, to assess the situation.
A gastroenterologist from Wellington Hospital will help with the procedure.
The zoo's manager of veterinary science, Lisa Argilla, says she's confident the penguin will survive the procedure.
She says while the zoo can restore the penguin to health, it will be too warm for the bird to remain in New Zealand during the summer.
A zoo spokesperson said the penguin was much brighter on Sunday, walking around and eating fish slurry - but was still on an IV drip.
Surgery 'worst case scenario'
Vets had on Friday cleared sand from the penguin's oesophagus, but x-rays showed more in its stomach. At the time they gave the penguin a 50% chance of survival.
They were able to pump water inside the penguin's stomach on Saturday to flush out a handful of sand, but said about eight to ten handfuls remained.
Ms Argilla says the worst case scenario is surgery but that would be potentially dangerous for the penguin, so vets are hoping they won't need to operate.
She says the sand could rupture the penguin's stomach and the longer it remains in the bird's system the more life-threatening it is.
As many as 100 people gathered at the operating theatre on Saturday to watch through the glass as the procedure was carried out.
The penguin's appearance so far from its home has also gained international attention with coverage by media in America, Australia, Britain, China and Canada.
The last recorded sighting of an emperor penguin in New Zealand was at Oreti Beach in Southland in 1967.
Emperor penguins are the largest of the penguin species. Adults can grow to more than a metre tall and weigh up to 30kg. They feed on fish, krill, squid and a wide range of marine invertebrates and hold the diving record at 450 metres deep and 11 minutes underwater.
Happy Feet offered free trip back to Antarctica
Economist Gareth Morgan has offered Happy Feet a free berth back to Antarctica.
Mr Morgan, who is leading an expedition to the icy continent, has offered the bird a spot on a Russian icebreaker when it leaves in February.
He says a sea passage would give the bird a chance to jump ship if it spotted some of its kin en route.
The penguin's gender isn't yet known - DNA results being processed by Massey University will reveal this.