Despite its size and capacity to travel long distances, new research shows the endangered Tasmanian wedge-tailed eagle does not travel far from ‘home’.
Researchers from the University of Tasmania’s School of Biological Sciences Chris Kozakiewicz, Dr Chris Burridge and Dr Scott Carver, studied the DNA of 228 eagles to understand the birds’ movements throughout Tasmania.
They analysed the DNA of individual eagles, looking at genetic relationships and geographic patterns.
“Here is a large bird that can fly long distances, yet they are not flying these long distances in terms of breeding locations,” Dr Burridge said.
“We found genetic patterns that they are mating close to where they hatched, or close to where they bred the year before last.
“In terms of how far a bird travels from hatching to first breeding season, or from one breeding season to the next, research shows the distances between locations of breeding for any one individual are fairly short.”
As part of the study, researchers also looked at extrinsic factors that could constrain the eagles’ dispersal, such as topography or habitat (vegetation).
“The extrinsic factors were not very influential in explaining the genetic pattern that we observed,” Dr Burridge said.
“It seems like factors relating to the eagles themselves, such as territorial behaviours, are governing their movements.”
There are between 1,000-1,500 threatened Tasmanian wedge-tailed eagles across 426 breeding territories in the State.
The bird was listed as endangered due to a low number of breeding pairs, high rates of unnatural mortality, and loss and disturbance of breeding habitat.
Dr Burridge said now knowing the birds do not travel far from its kin, more work needs to be done to understand the birds’ relationship to its immediate surrounds.
“We now know they are not moving far, but what is it that’s around them that’s important to them,” he said.
“It’s important we make sure on a small spatial scale the eagles have what they need.”
Dr Burridge is currently supervising a research project which is following eagles’ movements on a real-time scale in a bid to better understand how the birds interact with the immediate habitat.
The research, Intrinsic factors drive spatial genetic variation in a highly vagile species, the wedge-tailed eagle Aquila audax, in Tasmania, was recently published in the Journal of Avian Biology.
University of Tasmania researchers were joined by colleagues Jeremy Austin (University of Adelaide) and Jill Shephard (Murdoch University) to undertake the research project.