Torched cars are causing fires and killing endangered frogs and ruining valuable research in the Newcastle area.

Wildlife ecologist Chad Beranek spends three nights a week trudging through swampland tagging threatened green and golden bell frogs with microchips.

But his research is under persistent threat from deliberately lit fires, which often spread from the torching of stolen cars.

"When we have people deliberately lighting fires here it ruins a whole bunch of habitat, it directly kills threatened species and it also ruins a lot of our research," he said.

"I don't want to spend anymore of my PhD wandering wastelands looking for corpses of the animals I love."

Mr Beranek conducts his research on Kooragang Island, on the outskirts of Newcastle in New South Wales.

This green gold bell frog was found burnt under this tyre on Kooragang Island after a fire last Saturday that destroyed 100 hectares. ( Supplied: John Hembra )

The island is a mixture of industrial land and coal loaders for the Port of Newcastle in the east and low-lying marshland and nature reserves in the west.

It also happens to be a stronghold for the green and golden bell frog, which only has around 40 population centres along the east coast of Australia left.

But Mr Beranek said the isolation of the area had made it a popular place to dump stolen cars.

"It's probably the closest remote area to the Newcastle CBD and it's publicly accessible at all times. The gates don't close at night time or anything, so it seems to be very attractive to people doing interesting things," he said.

"Just in this last couple of months, since August, I've recorded at least eight burnt-out cars and it seems like a substantial increase and I'm not sure why.

"Their actions are just causing suffering of the animals really. There are threatened animals on the island that need protection and not destruction."

This slow-moving eastern long-necked turtle was not fast enough to escape a fire lit on Kooragang Island in February last year. ( Supplied: Chad Beranek )

On Saturday a fire that began from a car fire burnt more than 100 hectares of land and required the response of multiple crews from NSW Fire and Rescue and the Rural Fire Service.

After surveying the damage this week, Mr Beranek said his main research site was spared due to the winds blowing east, but another site with frog traps that took weeks to establish was destroyed.

"When a fire comes through like this it can alter our findings and can impact on what the data is saying about the size of the frog populations and the impacts on them," he said.

"For me it should be salvageable, data-wise, but I think the main impact is that it went through some really productive natural bell frog habitat.

"Fire is a natural part of the Australian ecosystem, but in this case we're in wetlands where fire doesn't play a huge role."

Mr Beranek said only one dead bell frog was found, but suspects many more would have been impacted along with many other species.

It is the second large deliberately lit fire on the island in the space of 12 months after a blaze in February, after which Mr Beranek said he found the charred corpses of eastern long-necked turtles, she-oak skinks, and striped marsh frogs.

The NSW Fire and Rescue Service could not provide figures on the number of cars dumped in the area, but a spokesman described it as a "constant problem".

The Rural Fire Service said, since December 1 last year, it had recorded 11 car fires in the neighbouring Port Stephens electorate and 12 in the Cessnock area.

"Unfortunately something like 11 car fires in one month is not unusual in some areas," RFS spokesman James Morris said.

"There has been a lot in the area lately and it's not strange to see one or two car fires and then a spate over a week and then a break. It's a fairly consistent pattern."