ACT News


Researcher harnesses GPS to follow where eagles dare

JUST five kilometres south of Parliament House a baby wedge-tailed eagle called Ein was part of a world-first GPS tracking study.

Catching a wedgie proved harder than anyone expected - setting up camp for 20 days, upwind from six trapping sites baited with 63 kangaroo carcasses (from road kill around the capital) didn't work, so University of Canberra honours student Felicity Hatton made do with a fledgling bird that fell out of its nest early.

Once attached with a snag-proof harness the GPS recorded the eagle's longitude, latitude, temperature and elevation every 90 minutes. A ball bearing in the tracker also showed whether the bird was sitting or in flight.

Juvenile eagles leave their parents' territory between three and five months after their first flight and Ms Hatton wanted to find out about this transition period. But getting close enough to download the stored information was a problem with the tracking antenna cutting out at one kilometre.

''I've been able to find her no problem almost every time I've been out there with binoculars but once I get close she flies away to the other side of the ridge.''

Ms Hatton has travelled more than 7000 kilometres chasing the bird but only managed to download information twice and has seven weeks of data.


''The longest flight was four kilometres - that's not a great distance. Within that 90 minutes she could have gone a lot further. And she was tracked at an altitude of 1000 metres.''

The battery for the GPS unit ran out this month and the harness was designed to fall off after six months, so unless the tracker is found the study is over.

Ms Hatton is still writing up her findings but the data has got her excited.

''I have observed Ein spending time following her parents around, and I noticed that over time the adults were introducing Ein to new habitats - first to open woodland with sparse vegetation, then to more dense woodland, then to very dense woodland on steep terrain on the side of a mountain,'' Ms Hatton said.

''The eagles would spend up to several weeks at each habitat before moving on to the next. By three months they would regularly move around all habitats.''

Tracking an adult will be her next project.

''I captured a juvenile so, instead of looking at the territory size of an adult, we were looking at juvenile behaviour post fledging. What they do once they have left the nest and how long it takes between when they leave the nest and when they disperse and find their own territory.''