A Northland woman who found a coconut on the beach one day and a washed-up dead turtle the next thought she must have gone tropical.
Kathy Wedge of Ruakaka, south of Whangarei, was amazed at her finds on Ruakaka Beach recently.
"Have the weather patterns changed, or is there a weird tidalflow? What's going on that we get a coconut and a turtle a day apart?"
Northland marine expert Wade Doak is convinced New Zealand's climate is becoming increasingly tropical.
Mr Doak said global warming had made Northland's waters an attractive option for several tropical species, both marine and insect.
Turtles, although endangered animals, were becoming more common.
Five species of turtle had been seen in New Zealand waters - green turtles, loggerheads, hawksbills, the leathery turtle and the Olive Ridley, which was very rare.
"A new species to Northland waters is the devil ray, and a man in the Bay of Plenty, which is basically the same body of water, caught five types of sunfish you don't normally see here," he said.
Mr Doak suspected that turtles could be breeding in Northland, after hearing of baby green turtles at Bland Bay on the eastern peninsula of Whangaruru Harbour, and Whale Bay, on the Bay of Islands' Purerua Peninsula.
Ms Wedge's turtle was identified as a green turtle by Department of Conservation officer Richard Parrish.
It had a 55cm-long shell with slash marks, possibly caused by a boat propeller.
Mr Parrish also believed turtle numbers could be increasing, but said it was difficult to prove from recorded numbers.
"Like whale strandings, there's far more reporting of them these days than there used to be. Far more people are getting to remote places than they used to."
Brian Gill, curator of land vertebrates at Auckland Museum, has collected records of turtle findings for the past 20 years.
He said there had been an increase in findings but said it could just be more cases being reported.
Mr Gill said 70 per cent of turtles were still alive when found, usually washed ashore or caught in fishing nets.
