A companion bird who flew the coop in Brisbane has been discovered as a stowaway on a cruise ship bound for New Zealand and quarantined in its own private cabin.

Harri the Australian galah was found on board The Sea Princess by staff last Thursday, four days into a 14-day cruise.

It's believed the pet bird left the family home and landed on the ship when it was docked in Brisbane on January 21.

New Zealand's Ministry for Primary Industries (MPI) said the only way for the cruise ship to enter the country was for Harri to either be euthanased, or secured and bonded to the vessel.

The Sea Princess is coming to the end of its 14-day journey. ( Supplied: Cleancruising.com.au )

So staff put Harri in an empty cabin.

Thankfully the cockatoo was microchipped, which eventually led authorities back to its owners in Brisbane.

Harri's veterinarian, Adrian Gallagher of Brisbane Bird Vet, said Harri had been missing for two weeks before being found.

"This is so lucky. They [Department of Agriculture] said they've never seen a story like this," Dr Gallagher said.

"From the owner's place to the wharf is probably not that far for a galah. That's my thought, he's escaped and landed on the boat.

"He's got a lot of character this bird. He's pretty ingenious.

"Apparently he's keeping everyone entertained on the cruise ship."

Dr Gallagher said Harri was due to be returned to Australia this Sunday.

The Sea Princess is due back in Brisbane on Sunday. ( Supplied: Princess Cruises )

"He's been microchipped for years, he's had all his health checks, and we've got his blood tests to say he's free of disease," he said.

"I think that helped the situation with getting him back to Australia."

Dr Gallagher said he had been in contact with Harri's family via email.

"He's booked in here next week for a check up with everything that's happened to him. That's got to be reasonably traumatic for him," he said.

Dr Gallagher said Harri's odyssey was an important lesson for all bird owners to make sure their pets were microchipped.

"We see stacks of lost birds. You've only got to go on RSPCA website to see how many there are. And one galah looks the same as the next galah," he said.

"These guys fly up to 60 kilometres per hour … so for him to go from Chermside to Hamilton he could be there in five minutes."

Carnival Australia spokesman David Jones said while Harri was cruising as a stowaway on Sea Princess, the pet's owners by chance were on another one of their cruises, Pacific Aria.

"It's truly unique," he said.

"It's a classic feel good story with everyone in the two cruise lines and government authorities doing everything they can to achieve a great family reunion when Sea Princess arrives in Brisbane on Sunday while accounting for all biosecurity requirements.

"Needless to say the lines are running hot between Sea Princess and Pacific Aria to give the family regular updates on Harri's progress."

The Pacific Aria is due back in Brisbane on Friday.

Harri quarantined in cabin until Australian return

There are strict conditions surrounding the remainder of Harri's high-sea adventure.

"The bird could have been carrying avian diseases with the potential to harm New Zealand's native bird population," MPI's border clearance services manager Andrew Spelman said.

"There was also a requirement for MPI officers to check on the bird and its containment facilities at every new port visit in New Zealand."

Mr Spelman said MPI needed photographic evidence of Harri's containment and the name of the officer looking after the bird.

"The vessel operators have been very particular in following our directive, so we're satisfied any biosecurity risk has been mitigated," he said.

Harri's journey was reminiscent of another recent animal adventure.

Rusty the dog, from Goondiwindi in Queensland, ended up 1,500 kilometres away in Snowtown, South Australia, after hitching a ride on a truck.