Nearly 5000 New Zealand nurses have registered to work in Australia since August. It shows the extent of those crossing - or planning to cross - the ditch, often to take up lucrative short-term contracts of up to NZ$8500 a week.

There is a huge nursing shortage here, a major contributor to delays in emergency departments, surgery and many other services.

Rotorua nurse Tracey Morgan had her last day at her community clinic on Thursday and was planning to go to Australia.

She was emotional, staying on hours after she was due to finish to help the only other nurse working.

"I didn't realise this day would come so fast and that I'd be ... real sad," she said.

Morgan, a former president of the union the Nurses Organisation, said like many nurses who have walked away, she loved her job but was burnt out.

"I didn't want to be one of those numbers, but they're not investing enough in the nurses that are here to keep us."

To be able to work in Australia, Kiwi nurses must first formally register with the Australian Health Practitioner Regulation Agency.

An agency spokesperson said since August, 4951 have done just that.

It did not measure how many went on to take up work.

Nurses Organisation kaiwhakahaere Kerri Nuku said it took a lot of effort to register so most of those who had, already had "one foot out the door."

Many were going for short stints, sometimes leaving their family behind for a few weeks, then coming home for a few weeks and going again, she said.

The good places to go were spread by word of mouth.

Te Whatu Ora chief executive Fepulea'i Margie Apa said the number who had registered in Australia was a serious worry if it resulted in people taking up jobs.

"We need every nurse that we can find in New Zealand as well as as many from overseas that we can attract to come and work here, so that is a real concern."

A Melbourne medical recruiter told RNZ short-term contracts ranged from about $3500 to about $8000 Australian dollars a week, depending on factors including seniority, expertise and the length of the contract.

The money included allowances, such as for working in a remote location.

Contracts started at about four weeks and went to about 18 months, and nurses had the ability to visit home during that time, she said.

Nuku said there was an additional worry that the health system was losing many Māori nurses to the short Australian contracts - they were already under-represented.

But she did not blame any nurse for taking up the opportunity.

"They're going over, they're getting better recognition, better pay, short term, and they can bring in additional money to the house hold budget."

There were about 65,000 nurses working in New Zealand, some of them part time.

Last year, the estimated shortage was 4000 but Te Whatu Ora said it did not know what the current situation was.

The Nurses Organisation said it wanted money specifically allocated in this year's budget for funding for nurses.

Te Whatu Ora's Margie Apa said the board had yet to put its recommendations to cabinet, but funding for staff was top of mind.