A brilliant black and white snap of two birds narrowly avoiding a mid-air collision has earned its photographer a prestigious prize, several years after it was taken.

The photograph Near Miss shows an osprey and spoonbill in flight above Western Australia's Mandurah Wetlands and was among almost 2000 entries submitted.

It was captured by amateur photographer David Rennie, who has now become Australian Geographic ANZANG Nature Photographer of the Year, a prize awarded by the South Australian Museum.

The judges praised the work for its "almost surreal quality" and "strong contrast between the birds and the moody sky."

Mr Rennie says he became fascinated by birds when he was a boy growing up on a farm not far from the wetlands and spent three years tracking the osprey's family with his camera.

"She was learning to fish and on that particular day she'd had five goes at hitting the water, came up empty," he said.

"After the fifth go, she actually looked back at her talons, opened and closed, opened and closed, and the spoonbill was just coming into land.

"The wings went up like parachutes.

"If you study something long enough, you start to see things they do and you start realise they're going to do something before they do it.

"They have tells just like a card player, a poker player.

"It was 'made luck'. It was absolute luck but I made it by being there.

"At that point, I stopped photographing and went home because I knew in my heart I might have cracked something really good."

Lonely life of a photographer

Mr Rennie, who has battled bipolar disorder, says the lonely life of the nature photographer helped him come to grips with the illness.

"I would love to look at books of birds and animal photos as a kid. That's where my pocket money went," he said.

"There were periods of my life where I couldn't work... and for about three years this was my little world.

"I would go out for a couple of weeks, three weeks, have three sleeps and shoot day and night. I learned to shoot during the night time. I would come back with ten thousand photographs and it was something for a while that was a little bit uncontrollable."

Mr Rennie says he has now given up photography but is delighted to be honoured with the prize.

He says he is extremely proud his three years of hard work crystallised in one perfect shot.

"I've always maintained the theory that... for every one thousand photographs I took, there's one that is a photograph you look at and go 'wow', that's the one and that shows everything you were doing in that period beforehand," he said.

"It boils down to one photograph."