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Wedge-tailed eagles tracked by researcher not afraid to spend time in the treetops

Simon Cherriman with an eaglet
Simon Cherriman checks up on an eaglet in a nest in the Perth Hills.

Supplied: Simon Cherriman

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Ecologist Simon Cherriman isn't afraid of heights.

Currently he's spending his days in the tree tops of the Perth Hills, keeping a watchful eye on a three-week-old wedge-tailed eaglet.

The young eagle has yet to develop any feathers, but in a few months it will take flight and leave the nest.

When it does, Mr Cherriman hopes to have attached a satellite tracker to the juvenile in an attempt to learn more about its life and the threats it faces.

Wedge-tailed eagle being fitted with satellite tracker
A juvenile wedge-tailed eagle being fitted with satellite tracker

ABC Radio Perth: Hilary Smale

"They make an incredible transformation," Mr Cherriman told ABC Radio Perth.

"The initial thing is that they hang around with mum and dad for a while before they depart on their gap year and go off into the wilderness.

"We don't really know that much about where they go in the wilderness, what the threats are and what the survival rates are like.

"With these GPS transmitters I am hoping to get lots more information."

Studying the lives of raptors

Mr Cherriman has been a student of the bush since he was a child.

As a young boy he built nesting boxes for possums in the family backyard.

As a teenager he took it up a notch, learning to climb the tall trees that hold theses nests.

He's been studying wedge-tailed eagles in Western Australia for 15 years and last year started a PhD into the lives of the raptors.

Mr Cherriman has added tracking devices to three juvenile eagles as part of his studies and is crowdfunding for four more to broaden his research.

He has made some surprising discoveries about one of the eagles he has tracked.

"We had a bird hang around in Perth for three months and then it flew to Karratha, and it only took three weeks to do that," he said of the 1,500-kilometre journey.

Eagle and drone
A wedge-tailed eagle swooped on a drone in WA's wheatbelt, taking off a propeller and damaging the camera.

Supplied: Leigh Nairn

The tracking technology has also helped Mr Cherriman learn more about what kills the raptors.

"I'm getting an increasing number calls from industry in Western Australia which are using drones for aerial survey work," he said.

While eagles have made headlines for their attacks on drones, what is less well known is that the drones can pose a danger to eagles.

"The bird that flew to the Pilbara, I found him dead a month afterwards," Mr Cherriman said.

"Something with a small, high-spinning rotor had managed to chop the wing feathers.

"I suspect it was a collision with a drone.

"He hadn't been able to fly after that and he died of starvation."

Eagle numbers unknown

Hundreds of thousands of wedge-tailed eagles were culled between 1928 and 1968 when bounties were offered.

Today, they are classed as least endangered, but exactly how many there are in the wild is unknown; the last population survey was conducted in the 1960s.

Mr Cherriman's study area covers around 2,500 square kilometres.

By searching ridges and hilltops for nests with binoculars, he has found 40 breeding pairs and their nests.

A wedge-tailed eagle nest in the Perth Hills
A wedge-tailed eagle nest in the Perth Hills

Supplied: Judy Dunlop

"But they don't all breed every year," he said.

"Some of them fail. Last year we had a nest blow down that had a chick on it and it was killed.

"So we have quite a few around but we don't really know exactly how many."

And despite being apex predators with a wing span of over two metres, wedge-tailed eagles are enormously vulnerable to human activity.

"I have found that mountain biking, four-wheel driving, motocross, all this intensive human use of habitat can be causing nesting failures," Mr Cherriman said.

"Then once they start moving, they face a whole number of threats in the arid zone."

Wedge-tailed eagle is currently being tracked
A wedge-tailed eagle currently being tracked by Simon Cherriman.

Supplied: Judy Dunlop

Collisions with aircraft, being hit by cars while feeding on roadkill and eating poisoned carcasses are the leading causes of death.

"There is an assumption that birds all have nests and fledge young and everyone lives happily ever after.

"But that is certainly not the case when you start investigating and following their stories."