Why are you tracking the chicks?
There's still a lot we don't know about what young white-tailed sea eagles do in their first three to four years of life in the UK. They don't migrate like the ospreys but they do wander far and wide around Scotland, maybe elsewhere in the UK and Ireland, maybe to Europe! Who knows?
It's a hazardous first few months and years; where and for how long do they stop to roost and feed, when do they make their first long flights from Mull, when are they independent of the adults Frisa and Skye and where and when will they start to think about settling down to breed?
This research study is managed by the Sea Eagle Project Team and Natural Research Ltd and will guide us in the future for all UK sea eagle reintroduction plans.
Being able to track the birds' journeys will add to our knowledge and understanding of the sea eagle's lives and can help inform future conservation work.
We're really excited about sharing this knowledge with sea eagle fans around the world. We know that thousands of people have enjoyed watching the young birds at the Loch Frisa hide on Mull and are sad when they leave Mull to go home without knowing what happens next. Residents of Mull too who help protect the sea eagles all year like to hear of their progress.
Well, now they can follow every flap and soar of what they'll be doing as they grow up. Brèagha (the female) and Mara (the male) are about to embark on the biggest journey of their lives and we're sure that you'll be as fascinated as we are by what happens to them after they've left Mull.
How do the tags work?
The youngsters will be fitted with small, solar-powered satellite tags that will transmit information about their journey. Initially, every hour – as long as the battery is charged up – the tag will send send the exact position (within 20 metres) on the Earth, as well as details of direction, speed of flight and altitude via the Global Positioning System (GPS) to our computer system. That way, we can build a very detailed picture of each bird's route.
Are the tags heavy for the chicks to carry?
The tag weighs just 70 grams, a tiny fraction of the chick's body weight. Thanks to bird of prey expert Roy Dennis's previous work with the Highland Foundation for Wildlife, we know that eagles can carry them without problems on thousands of miles of successful flight for many years. If the tags and rings affected the birds' behaviour, it would make the research invalid.
How are the tags attached to the birds?
A member of the Mull Eagle Watch team climbed up the nest tree and carefully took the chicks out of the nest. They were gently lowered down to the ground in a bag.
Before fitting the tags, Roy examined each chick thoroughly to check that it was healthy and strong. We also took some biometric measurements – eg. wing length, bill depth – and we found out what sex the chicks are via DNA work by Natural Research Ltd – a male and female. The birds' welfare and safety always comes first.
Each chick was also ringed this year with a British Trust for Ornithology lightweight metal ring and a coloured aluminium leg ring on the other leg, to help identify them in future. This colour ring is part of the Europe-wide sea eagle colour ringing programme. The tag - the size of a small match box - is attached to a harness that the bird wears a bit like the straps of a tiny rucksack.
The adult sea eagles Frisa and Skye returned soon afterwards to carry on feeding as normal.
How long will the tags last for?
The tag will operate for three to four years, provided the battery is charged with good levels of sunlight from a little solar panel. Sometimes the tags don't work so well while the birds sit around in forestry plantations and around the nest, but they shouldn't be short of sunlight (even on Mull and the west coast of Scotland!) once they head off on their wanderings. When the project ends possibly in three or four years time, the tags will drop off harmlessly and will be retrieved by us for future use.
How can we follow what happens to the sea eagles?
In the Mull Eagle Watch hide at Loch Frisa (until the end of season closure at the end of August) we'll have staff on hand to let you know what's happening. Come and visit and maybe see the chicks and Frisa and Skye for yourself.
Later this year, Bill Oddie, Kate Humble, Simon King and Gordon Buchanan will be following their progress on Autumnwatch. In the meantime, the RSPB's Mull Officer Dave Sexton will be watching their every move and will keep you posted on a regular blog.
If you can't join us on Mull, don't worry – you'll be able to keep up with the latest news on the RSPB website, using Google Earth satellite maps to pinpoint their locations.