The story behind the cliffhanger

Earlier on 'Autumnwatch', we saw Mara make his maiden flight and Breagha wasn't too far behind, both unaffected by their satellite tags. Both are now doing well as you can see from the current map. But that time of joy at seeing the two chicks in the air was short-lived. As you can now see on the full unedited version of Wednesday's Mull Eagle Diary on the BBC 'Autumnwatch' website (click on 'Meet the Animals'), it was a very dangerous time for a young sea eagle elsewhere on Mull.

Below is another chance to read a Blog from earlier in the summer which takes up the story and explains the background to what you'll see on Thursday's final 'Autumnwatch' for 2008. And afterwards on this Blog, I'll be bringing you up to date on what's happening in that particular territory now.

Meanwhile, back in August...In addition to our Loch Frisa twins, we have another six sea eagle chicks this year on Mull to keep tabs on. They don't have the benefit of sat tags and are in remoter parts of the island so to check on their progress means some good old fashioned fieldwork.

Of course we can't keep an eye on them all the time; they've all now fledged and are wild birds to go where they please but just for our peace of mind, I like to at least know they've made it through their first few weeks out of the nest.

Generally when they get to the fledging stage, they are fine and do well. At one site, after a fruitless search and listening hard for loud food begging calls, there was nothing. So I switched my attention to the mainland opposite and there were the two adults sitting by the shoreline, occasionally shooting off to grab fish from the surface of the Sound of Mull.

Then, much to my surprise after slightly fearing the worst at seeing them together so far from their nest area, in flew their single chick to harass the adult for a piece of  fresh mackerel. That chick was clearly doing very well and had already flown across the sea and away from Mull. Success! And one less chick to worry about.

Onto the next site which had also had a single chick. This chick had been on a nest visible from a public road and had been watched and guarded carefully by local people and many passing tourists. As far as we all knew it had fledged normally. One morning it was standing on the edge of the nest, flapping like mad and exercising those huge wings and flight muscles. On the next check just 45 minutes later, it had gone - right on cue! Another success!

Chicks often sit around alot, usually on the ground after their first flight and need time to recover from the shock at being out of the safety and comfort of the nest - the only place they've known for the last 3 months since hatching. And they're often in thick forestry areas so we have to depend on watching the behaviour of the adults and calls from the chick. But something wasn't right. A few days later there had been no calls heard. The chicks can be very loud when calling for food.

I decided to go into the Forestry Commission Scotland plantation for a closer look and walked down through the rows of trees. I don't usually like doing this as if the chick was sitting nearby, it could have spooked into flying off. The female was sitting on the nest tree watching me approach. That looked like a good sign but still no calling. I sat and waited, hoping to hear a call. Nothing. It was time to go right in.

The female flew away. She didn't make any alarm calls as she would have done had the chick been close by. Maybe it had just flown further than we'd all thought - like at the first site I'd checked? I was now within a few metres of the vast towering nest tree. I didn't want to but knew I had to check around the base of the tree - just in case. There was a feather fluttering in the breeze; then another and another.

By now, I just knew what I was going to find but the shock of it was no less intense. Lying on her back at the base of the tree, spread over the giant roots, was our chick. Her giant yellow talons curled tightly shut, her head turned to one side. She hadn't fledged, she had fallen or been blown off the nest in a sudden gust just before she was quite ready to go. Perhaps a part of the nest had given way beneath her as she jumped up and down flapping hard and she found herself falling out of control through the unforgiving branches from some 90 feet up.

The only consolation was that it looked like she'd died instantly as she hit the hard roots and hadn't sat there injured and suffering for several days. All that effort by her; all that effort by the parents; all that effort by the people watching over her. She'd given hundreds, maybe thousands of people an unforgettable experience of watching a wild sea eagle chick in the nest. But there's a very thin line between life and death for these eagles in this environment and for this young eagle there was to be no soaring over nearby sea cliffs or chasing after other young eagles in Mull's autumn skies.

As I sat on a tree trunk next to her I was suddenly jolted back to considering if I had enough plastic bags with me for her remains and thinking I'd better gather her up to send to the museum. But then I wondered about the female who had been sitting on the nest tree above this sad bundle of feathers. Was she still looking for the chick? It's perfectly possible. But soon enough, her and her mate will start selecting a site for next year and start nest building all over again. With that positive thought, I gathered things together and trudged back through the forest.

www.bbc.co.uk/autumnwatch/meettheanimals

Dave Sexton RSPB Scotland Mull Officer

'Autumnwatch' is coming to an end! Catch the final show Thursday night BBC Two 8pm. Watch the drama described above and find out the latest from this pair of sea eagles and discover how Mara and Breagha are faring in the big, wide world.