A filmmaker says feral pig numbers in the world-heritage listed Daintree Rainforest in far north Queensland are out of control.

University of New South Wales doctoral student Dan Hunter has spent the past nine months filming cassowaries in the Cooper Creek area, north of Cairns, in what is thought to be the world's oldest surviving rainforest.

Cassowaries are listed as endangered, with as few as 2,500 believed to remain in the wild, and Mr Hunter said he can see why.

"The feral pig problem is out of control in national parks," Mr Hunter said.

Feral pigs are eating cassowary eggs and chicks in the Daintree Rainforest. ( Supplied: Dan Hunter/The Natural History Unit )

"They are eating the eggs and chicks as they compete for food.

"The pig-hunting dogs that get lost in the national park are a big problem too, they go after them [the cassowaries]."

Mr Hunter said he battled leaches and mosquitoes in his 'hide' — a canvas tent — to capture the big and potentially deadly birds for the film Dino Birds, to be screened on National Geographic.

He said getting up close and personal with the birds, which can reach two metres high and weigh 80 kilograms, was an "incredible" experience.

"This one particular day they walked under a tree that was fruiting," he said.

"They launched themselves about one metre into the air. It was an amazing thing to see."

He said the endangered species can also be a bit "creepy".

"For such a big animal they are incredibly stealthy," he said.

"You can be so close to them and yet you wouldn't even know they are there. The next minute they're appearing over your shoulder."

Male cassowaries amazing fathers

He said one of the things he found most surprising about his time with cassowaries was how paternal they are.

Male cassowaries make "amazing fathers" and even teach their chicks how to swim. ( Supplied: Dan Hunter/The Natural History Unit )

"Cassowaries are one of the most incredible fathers on earth," he said.

"They sit on the eggs for 55 days and don't move.

"The chicks hatch and they escort them through the forest for the next year of their life.

"They protect them from everything — feral pigs, dingoes, and teach them how to swim."

He said he hoped the documentary, which is screening to a world-wide audience, would help with conservation efforts to save the big bird.

"If people get excited about cassowaries, if tourists visit the country to see them, then it benefits tourism. People will be more inclined to look after them," he said.