Police Association boss Chris Cahill said a number of factors were behind the squeeze on Northland police. One was a spate of serious crimes, especially homicides, in the past year. Homicide inquiries were "resource intensive" and sucked up a lot of staff for long periods of time.
Police bosses had sent in extra staff from outside Northland to help but that was only a short-term fix.
Major crimes also had a compounding effect because staff built up a lot of overtime. They eventually had to take time off, adding to the pressure on remaining staff.
Another factor was a shift of frontline staff into prevention roles, Mr Cahill said. It would pay off in the long term through lower crime rates but until then it meant extra pressure on the frontline officers who were left.
Northland police also faced recruiting challenges and social factors contributing to crime such as high unemployment.
"There's some pretty stressed staff up there. They will start falling over. Police operate on a lot of good will but everyone has a breaking point."
Mr Cahill said the answer in the first place was to recognise the problem, which Wellington was starting to do. In the long term staff numbers had to be increased and Northland needed a specific recruiting programme.
The Greens' Northland-based police spokesman, David Clendon, said officers on the ground kept telling him they were over-stretched and unable to do their jobs properly.
As well as more police, Northland needed more investment in mental heath services and treatment for drug and alcohol addiction, one of the major causes of crime.
Mr Clendon hoped the new Police Minister would be more receptive to staff concerns than her predecessor. The outgoing minister was "dismissive" yet had no trouble finding money for new prisons.
Police found it demotivating to be told they were politicising the issue any time they said they didn't have enough staff, Mr Clendon said.
Inspector Al Symonds, Northland police deployment manager, said 2016 had been a busy year but the claim that people were not being arrested due to insufficient staff was "a bit disingenuous".
Arrests were down because police were making more use of pre-charge warnings - designed for "good people who do stupid things" - or summoning people to court at a later date instead of taking them back to the cells.
Police had recently trained a number of new jailers and prisoners from other parts of Northland could be transported to Whangarei's 24-hour station if necessary.
During the Christmas break Northland was in line for extra support with 30 Auckland officers set to be deployed across Northland for two weeks. In previous years Auckland had sent 5-10 officers, mostly to the Bay of Islands on New Year's Eve.
In addition, road police from the Waitemata district would patrol all the way up to Marsden Pt, freeing Whangarei police to push further north.
"So I'm confident we will have what we need," Mr Symonds said.
Paula Bennett the new Police Minister, said she was not prepared to comment on police numbers at this time.
According to the Police Association, New Zealand has one police officer for every 526 people while Australia has one to 432. In Queensland, which had an urban-rural split similar to New Zealand's, the ratio is 1:416.
Mr Cahill said there was no "magic number" for staffing ratios, especially in a district like the Far North with its large distances, rural stations and high unemployment. It was a case of looking at each community and seeing what numbers were appropriate, he said.
