Auckland ratepayers face a $100,000 vandalism bill after damage to property in parks where kauri tracks have been closed for upgrades.
Park rangers say the acts of destruction, which included stealing dozens of signs and cameras, seem to be a type of protest.
Vandalism in local and regional parks also included incidents of ripped fencing, damaged cameras and signs, theft of spray guns and brushes and broken hygiene stations.
Auckland Mayor Phil Goff said the destruction had wasted scarce resources and endangered the environment.
"This sort of irresponsible and pathetic behaviour has cost ratepayers more than $100,000 and wasted hours of staff time," he said.
"Not only is it putting our iconic kauri trees at risk, but it's also taking up staff time that could be better spent upgrading and maintaining tracks in our parks.
"Auckland Council is working hard to reopen tracks so Aucklanders can get out and enjoy the parks and reserves this summer. Senseless behaviour by a small number of people is holding back this work."
He is urging anyone with information to call the council or the police to catch those responsible.
Local parks had been most affected, with an $80,000 bill for the replacement of damaged or stolen fencing and signage.
In the Waitākere Ranges, from Feb 2019 to July 2020, upwards of 60 signs had been replaced and 21 significant repairs to fences have been completed at a cost of around $22,500.
The figure didn't include minor repairs to fences or reinstalling signs that have been pulled off or knocked over.
Park rangers were dejected by actions, with precious time and resources being diverted away from vital conservation work, upgrading and maintaining tracks.
"Vandalism has always occurred in regional parks but the specific and deliberate damage to track barriers, signs and the wilful cutting of sterigene lines would appear to be a form of protest," Stu Leighton, senior ranger - kauri dieback management, said.
Since April 2019 when cameras came into use, 17 have gone missing and had to be replaced, across both regional and local parks, at a cost of $6800.
Manager kauri dieback track specialist, Grant Jennings, said a small minority of people seemed to be involved and urged them to rethink.
"This holiday season, I'd ask everyone to play their part and respect our community parks so they can continue to be enjoyed by families."