The night the earth moved

The sturdy oaks will have offered their usual sanctuary for an eagle looking for a safe roost site. Last night the Hebridean skies were clear and the temperature plummeted below freezing. By late afternoon, as the light was fading, three young sea eagles dropped out of the dark sky, circled and chased each other once or twice before vanishing out of sight into the wood. Their haunting calls echoed round the glen for a few minutes and then there was silence. In the adjoining wood sat the resident territorial adults, side by side, offering warmth to each other for the long winter's night ahead. So, at least five eagles in close proximity, maybe there were more. But all were together in a traditional eagle haven. Safe for the night. Or were they?

Somewhere deep underground, the earth was restless. The vast plates of the Great Glen Fault were straining to shift. Hard rock scraping against rock, barely discernable movements. But the pressure was building. The force was becoming impossible to halt. Miles down in the earth's core, ancient magma from Mull's volcanic past still flowed. One day, somewhere on the planet, it would erupt again but not here. Not tonight. Or would it?

The signs were ominous. Back in the wood, the eagles stirred. Some unkown sense had alerted them to an approaching storm. But the skies were still cloudless and the stars flickered and shone brightly in the inky blackness. There was no moon. For a few moments it seemed the darkest it had ever been and the eagles were all tense. The youngsters sitting apart from each other felt especially vulnerable. It was a sensation none of them had known before and they had no way of knowing how to react . The adults had comfort with each other, their soft plumage almost interwined. Together but still unnerved.

It started at 05:39am. It began shaking its way up through the deep spreading roots of the old oaks and it grew in intensity. The eagles were all startled at once. Gulls on the sea loch were calling out, strange, previously unheard alarms. There was no wind but proper waves were lapping suddenly and roughly onto the pebble shore of the loch which had been flat calm just seconds before. In the darkness, the young eagles could only sit and stare out, their talons clenching ever tighter into the lichen-covered branches. Somewhere in the same wood, a small flock of sheep also huddled close together for warmth suddenly scattered in all directions, stumbling across boulders and roots. On the far side of the loch, the cattle were bellowing loudly - cows searching for calves, calves seeking mothers. A flock of greylag geese rose into the air as one as panic engulfed them. But the birds of the night, the tawny owls which had been hooting in territorial disputes, fell silent.

Early this morning as the island slumbered away the weekend, at 05.39:54.2, the earthquake hit Mull. Its epicentre was deep in the earth beneath the roost trees of the eagles. The rumble grew to a crescendo; it sent thunderous waves through the land. High on the frozen scree slopes of Ben More, a shower of ice-shattered Igneous rock tumbled down the mountain as a herd of red deer dodged the flying missiles. Further round the coast, some rocks made it all the way down and bounced wildly onto the Gribun road. The eagles were on the verge of taking flight, but it was still dark. Every instinct was telling them not to, it wouldn't be safe. And yet every tense flight muscle was urging them to flee this unseen danger. It must have been terrifying.

A few miles away I was jolted awake from a deep sleep by the rush and roar of the primeval shudder which shook the foundations. At times like this, you are instantly wide awake, heart thumping, tense, straining to hear, trying to gather your senses. But all was silent. Was it thunder? An explosion maybe? As the minutes passed, you suddenly realise you've been holding your breath and you start to breathe again. The heart rate returned to near normal but any return to sleep was a long way off. What had just happened - could it really have been an earthquake? And what of the eagles now settling again back at their roost in the old oak wood? They couldn't comprehend the events of the night. The fearless, strong eagles had known fear and weakness for the first time in their lives - but they had survived. The cattle were calm again; the loch's ripples had eased and the sheep had settled. Even the owls had resumed their nightly challenges. On a nearby farm, a frantic sheepdog was still barking but nothing new there.

Mull had just had a very modest reminder of its violent geological past and we'd all experienced the unbelievable force of a restless Mother Earth. It was just the smallest, tiniest  glimpse imaginable of what terror and destruction some parts of the globe have endured over time. Even our little rumble in the hills had caused a momentary panic in the soul. But for us, the sun came up again on another beautiful, frosty day and the eagles flew from their roost at daybreak and away into the mountains. Our little bit of Mull really had moved - just a bit - the British Geological Survey said it did. For us all, it would be a night to remember.

Dave Sexton. RSPB Mull Officer