Mr Taylor said a small campfire that someone had tried to extinguish, and cover with soil, appeared to be the likely cause, wind blowing embers into nearby pine needles.
"It's madness to have any sort of fire close to vegetation at this time,"he said, adding that the ground crews' job was made difficult by the inaccessible location, off Ngawhitu Road.
Two fires on Tuesday afternoon had not been malicious but had been caused by people not paying heed to the fire danger. Two helicopters were sent to a vegetation fire near State Highway 12, South Hokianga, sparked by fireworks about 5.35pm, while a grass fire at Ahipara about 5.50pm was started by a Kaka Street land owner.
Earlier in the day, about 11.45am, a helicopter was dispatched to Hukatere Road, Pukenui but was not needed, the property owner extinguishing what was described as a small grass fire.
Mr Taylor said the authority was investigating all four fires, and would recover its costs wherever the people responsible could be identified. In the case of the Hokianga fire, two helicopters had flown from Paihia, a trip of about 20 minutes each way, costing more than $2000 even before the choppers got to work.