If an animal is declared extinct more than 80 years ago, most people would assume it no longer exists — but Neil Waters is not one of those people.

Key points: The last known thylacine died in captivity in Tasmania in 1936

The last known thylacine died in captivity in Tasmania in 1936 Despite officially listed as extinct, many people believe the species has survived in remote areas of Tasmania and the mainland

Despite officially listed as extinct, many people believe the species has survived in remote areas of Tasmania and the mainland A Tasmanian group of believers and the continuing quest for proof is about to become the subject of a documentary film

Neither are the almost 8,000 members of his Facebook group.

"When you talk to scientists about thylacines, you're a bit of a tinfoil hat whack job, because once an animal's declared extinct, that's it, case closed … but they're out there," he said.

Mr Waters is the president of the Thylacine Awareness Group of Australia, a collection of believers who are convinced the Tasmanian tiger — once the dominant predator across Australia — still roams the island state, and maybe even the mainland.

"I had two sightings in Tassie myself," Mr Waters, who lives in Tasmania's north, said.

Neil Waters (left) with filmmaker David Elliot-Jones. ( Supplied: Screen Australia )

"One in 2010 when I was taking the dog for a walk and the second in 2014, when I happened to be peering out my bedroom window and one came walking past late at night."

The Facebook group and website serve as forums for sharing the items of evidence gathered by people across the country, who also swap notes on the movements, habits and mannerisms of the animal.

Since starting his group in 2014, Mr Waters said he had been "dumbfounded that there was so much information [that] wasn't in the public arena".

Mr Waters said he, and others, use "basic, citizen science" to find "concrete evidence" of the thylacine's continued existence — employing various types of technology, including cameras and thermal-imaging drones.

"There are plenty of large, interesting footprints in the area where I live, which makes us think there's still plenty around," he said.

"We find the odd kangaroo with its head missing, which is also an indication they're in the area because they like to feed on the blood-filled organs of smaller marsupials."

A mother Tasmanian tiger with cubs, on show at Mary Grant Roberts' Beaumaris Zoo in Hobart in the 1920s. ( Tasmanian Museum and Art Gallery )

Photos of animals torn apart by larger predators, along with images of paw prints, night-vision captures of wildlife in the bush and video stills of what are purported to be sightings also feature on the group's webpages.

"It gives people a safe place to talk about their information where they wouldn't be laughed at or ridiculed," Mr Waters said.

"The world is in dire need of good news stories right now and anything that gives people hope and a bit of a focus on the future is going to be a good thing."

'People are seeing something'

The quest for the thylacine has attracted the attention of documentary makers David Elliot-Jones and Naomi Ball, with Screen Australia awarding them a $50,000 grant to make Searching for the Tassie Tiger, a documentary project which will follow Mr Waters and members of his group.

Neil Waters said the filmmakers could see the "importance of what we're doing". ( Facebook: Thylacine Awareness Group of Australia )

The film, which will be distributed globally by Vice Media, will be shot mostly in north-east and north-west Tasmania, once the coronavirus crisis is over.

"I was really drawn to it because of the environmental element of it," said the film's director, Naomi Ball.

"It's very much the same as what we're doing to our environment now on a much larger scale and with the bushfire season that we've had, we're really seeing what human impact can do to our environment."

Ms Ball said despite the official status of the tiger as being extinct, "people are seeing something".

She said it would be "wild" if they managed to capture a thylacine on camera, but that was not their main goal.

"If that happens, I'm going to be absolutely blown away," she said.

"But we're really focussed on the search, the people that are searching and the characters that they are, the reason why they've come to the search and why they've made it their fight."

The last known thylacine died in captivity at Hobart's Beaumaris Zoo, in 1936. ( Supplied: Tasmanian Archives )

Mr Waters said the filmmakers could see the "importance of what we're doing".

"They want to give us the opportunity to get that story out there a little bit further, on an international level, where it really deserves to be," he said.

But what of the sceptics? What does Mr Waters say to them?

"I'd just tell those people to sit tight and be patient and we'll try to address that for them."

The producers hope to finish filming by September and release the film next year.