0836 GMT December 03, 2020
Researchers have climbed some of Tasmania's highest trees to attach GPS trackers to 25 young eagles around the state, to study their flight paths and help ensure their future, abc.net.au reported.
Threats to wedge-tailed eagles include collisions with power lines, vehicles, fences, and wind turbines, and poisoning and loss of habitat.
In 2017-18, 29 wedge-tailed eagles were killed — a dramatic rise from the 12 killed in the preceding 12 months.
Researcher James Pay said trees were scaled to around 80 meters or more to retrieve juvenile eagles briefly from the nest.
Teams climb with ropes and harnesses to pluck the young eagles from the nests.
Wedge-tailed eagles like to build their nests in the tallest trees in the Tasmanian wilderness.
The young birds, capable of flight, are fitted with a light-weight tracker on the ground and then returned to the nest immediately.
"They're super-sensitive to disturbance during the breeding season, so if we get too close to their nests they will abandon their chicks," Pay said.
"So we have to be super careful with this part of the research.
"We time it so it is right at the end of the breeding season, when the adults aren't in the nest as often because the chick is almost fully grown."
The team then scale the tree again and place the young eagle back in its nest before a parent returns.
Pay gets text messages updating him on the eagles' locations, and flight paths of the birds can be mapped out, including flight heights.
"Over the last five years, the number of texts I've had from wedge-tailed eagles far outnumbers the texts I've had from people," he said.
Their location is updated every six seconds. The project is shedding light on Australia's largest bird of prey. Researchers hope to use the data to reduce deaths. One of the main causes of death in Tasmania is from collisions with power lines.
"If we know where birds are flying low we can put up these things like bird flappers that makes the power lines more visible to the eagles and reduces the likelihood of crashing into the power lines themselves," Pay said.
They're also discovering how far the birds fly. One bird, named Wyatt, flew nearly 250 kilometers around Tasmania in eight hours.
"We didn't know how far they flew," Pay said.
"There was some tracking done on the mainland where they've flown thousands of kilometers because they have more space to travel in, but we didn't know how they travel around Tasmania.
"What we found is they fly a lot and cover large distances but it's not in a straight line."
Juvenile birds also stay with their parents a lot longer than previously thought.
"We expected it to last four or six months but it lasted way longer, we still had birds with mom and dad to about 20 months, they didn't want to leave home."
Zoologist Clare Hawkins said the research would be extremely valuable.
"We'll understand so much better what the true threats are for eagles," she said.
"There's this great long list that we suspect are problems but with this we'll actually be able to see what is happening with these eagles — where are they going? What are they encountering? And ultimately we're going to be seeing what is causing any deaths."
The next stage of the project will be to track adult eagles to see how their flight paths compare with the very young adults.
TasNetwork's pledged in 2017 to invest $600,000 to install infrastructure that would reduce the impact on the threatened birds.
Tasmanian wedge-tailed eagles are classified as endangered, with the adult population estimated at about 350 breeding pairs.