I didn't just retrace my steps in the mud. I pretty much jogged as fast as my exhausted legs and aching body could manage. Admittedly that probably wasn't very fast but it felt like a Herculean effort to me at nearly 6 o'clock in the evening.

I arrived back at where I'd started; checked the phone message and grid reference again, set up the 'scope and aimed it at the point my informant had told me he'd seen an adult sea eagle perching for the last few hours. It had flown off once or twice that afternoon but had returned to the same general area. This had to be a promising sign.

I focused the eyepiece and there it was. Still there. Preening and settled. Half an hour later it flew out to sea and I lost sight of it behind a small island. It didn't return. I knew now that with the late July evening light still quite good it was worth a short trip up into the forestry. I found a steep, winding timber extraction track and followed it higher and higher up the hillside.

I finally reached the area where the bird had been perching. Nothing. Silence. I was now very hungry. The sweat from earlier had cooled and I felt a chill creeping up my spine. I probably had done all I could. The Territory 40 birds had beaten us again. I'd missed the last ferry back home to Mull. I needed to eat, find a B&B and warm up. There was no way I was sleeping in the landrover that night.

As I stood up from my seat on a damp tree stump, I heard a flock of common gulls flying over. I watched them go past. Suddenly they veered off to the back of the forest and started to give their familiar alarm calls. Familiar beacuse I hear them on Mull whenever a sea eagle is anywhere nearby. They are a great early warning system. At that moment, the 'hassled' call of a sea eagle rang out around the trees. The gulls must be mobbing a bird perched somewhere out of sight. It all went quiet again.

Summoning the last vestiges of energy from my tired limbs, I crept up the side of a burn in the general direction of the calls. All of a sudden I had that sixth sense that I was on the right track, indeed maybe on the final leg of my quest.

Nothing could stop me now - exhaustion, hunger - I was like a bloodhound on the scent! The adrenalin was pumping.

As I neared the top of the wood, a shape to my right made me look across the burn and there was my dream find of the year - if not my career! A whopping great sea eagle's nest in an old spreading Scots pine; it was covered in flecks of down, bits of old prey - there must be young but the nest looked empty!

And with that, my eyes alighted upon the young eagle, watching my every step long before I'd seen it. It had already 'branched' and was sitting to one side of the nest on a limb of the pine. I stopped breathing. I waited a second to drink in the scene but instantly worried the young eagle might jump. I slithered back down the peat bank and out of sight.

But as I stopped I actually wondered if I'd just imagined the whole event. I was so pumped up to find this nest and had imagined this moment a thousand times in my head. Maybe I'd slipped into a dream-like state and it was all make-believe? I had to take a second look. So I inched back and saw it all again.

The young eagle was still watching me, wondering what on earth this mad man was up to. This time I watched for a full minute before retreating, this time convinced but still pinching myself. At no time had the adult perched nearby flown out or called. No-one knew I'd been there except me and the chick. It was just the best feeling.

I called a few people and sent a few texts when I got out of the forest and back at the landrover. I didn't want to gloat - but I couldn't help it  - just a wee bit! My first call was to home when my daughter answered. She was ready for bed. "Daddy, did you find the eagles?" I could barely get my answer out and I felt like shouting but I half whispered: "I found them!"

That evening, now gone 9pm, I found the last room in a wonderful inn and after a long shower, settled down for a celebratory bar supper of local fish and chips and a long, cold pint (or two). It was truly a night to remember. The chick was too big and advanced to ring or anything. But all that mattered was that we'd found him. I'd been in the right place at the right time. All the other leg work by others before me had cancelled out some areas and narrowed the search but I was still going to enjoy this moment.

That night I slept long and deep. Now that's what I call job satisfaction.

Dave Sexton RSPB Scotland Mull Officer

Tonight the messages of support for our campaign to stop the poisoning of our wildlife like Mull sea eagle youngster White G continue to come in and we're truly grateful. Just before writing this blog tonight, BBC Countryfile presenter John Craven emailed with his personal condemnation of this crime. Others like Simon King, Chris Packham and Mike Dilger have joined the chorus. Read their views in tomorrow's Scotsman newspaper. Maybe the tide is turning against those few irresponsible sporting estates which kill our protected species without a second thought for their actions. As John Craven said: "Watching the sea eagles in flight on Mull was one of my greatest experiences during many years of reporting on UK wildlife. There can be no excuse for this senseless killing".

Please help keep the pressure on.

I'm on the move away from Mull for the next few nights but will let you know of any new satellite data if we get it.