Each little shift that the earth makes around the sun, and the moon around the earth, influences the natural world causing wonders like the seasons' change, the spring growth of flowers, the colours of autumn and the endless migrations of birds.

Some of these birds come to Coll for it's summer bountifulness, others in winter to seek solace from the harshness of the winter night. Many pass by, stopping only to feed and rest before heading out across a churning sea with only their destination as baggage, their destination known only by the stars that guide them.

The life of a nature reserve warden is as dependant on these natural rhythms of season and weather as that of a farmer. Feeding cattle, hunched and shivering in the darkness of a January gale is a long way removed from Spring when lambs stretch out in the sun and you can almost hear the grass growing.

My favourite days are in early summer when a typical working day starts at midnight. Eager with anticipation, almost like a Bushman preparing for a hunt, I will have sat on the bench outside Totronald watching the light fade, seeing the darkness slide in across the landscape like a blanket, darkening hollows, filling in the contours and rising up gradually as the northern sky remains pale and bruised.

The sounds change. You become aware of a distant humming and buzzing as the snipe fly up, invisible as ever. Suddenly one power dives above your head, vibrating its tail feathers - a mechanical song. The corncrakes are hesitantly tuning up as the males return to their favoured patch of the field: preparing for a vocal extravaganza. These birds have flown all the way from southern Africa and will probably have only one short summer chance to mate and pass on their genes. Like the salmon, which also has only one chance to breed, evolution drives the comcrake to perform the vocal equivalent of the salmon leaping a waterfall in spate. And what an impressive sound it is. By midnight the quiet night is bedlam and gleefully I slip out to count the corncrakes.

Hear them calling, plot their positions on a map: sounds easy, but corncrakes are masters of ventriloquy. As they turn their heads the sound comes and goes, walls and rocks are used as echo boxes and amplifiers, not every bird will call on any one night, but on good nights with up to a dozen birds calling around you the sound coalesces into a disorientating and numbing noise.

The adrenalin of the hunt is there as you creep up to each one to make sure you've got him pin-pointed. Then backing off, and on to find the next one. By 2.00am the sky is expanding down into the hollows. Darkness is becoming opaque and then lightening. Skylarks are now vying with the snipe. The land is re-emerging from the night and time is short. Comcrakes have to be surveyed between midnight and 3.00am, when calling is at its peak, and I need to get on.

An hour later when I stop many corncrakes are falling silent and beginning to wander off into the meadows feeding, giving occasional bursts of song as they go. The landscape is holding itself still, fresh with dew as the new day dawns. The larks are serenading the sun, flying up ever higher as though they must meet the first rays and usher them down to the land that slowly breathes out puffs of mist from flat fields and hollows. Sitting on a knoll with a flask of coffee as the sun rises, you are the only person in the world and the rebirth of the land is sacred.

Counting birds - monitoring population levels - is an important part of my work. It is only by having good data collected over several years that you can build up an accurate picture of how a particular species is faring. By counting birds systematically I can see how the habitat management work on the reserve is benefiting those species and how or where the work needs refining. Conversely it is only by analysis of regular counts that it is now known that once common farmland birds such as skylarks, song thrushes and lapwings are experiencing massive population crashes on the mainland where agriculture tends to be more intensive.

So once the coffee is finished, it's time to monitor the wading birds. As with corncrakes, there is a particular way to survey fields for snipe, lapwing, redshank and dunlin. The timing is important to ensure consistency between counts so, typically, it involves more anti-social hours - within three hours of dawn in good weather.

As the sun gains height I am in a marsh, trying to look at my feet so I don't go over my wellies and trying to count the mob of lapwings overhead without missing the redshank that scoot off sideways, or the dunlin that sits tamely and tinnily on a tussock before launching himself into a parachuting display fight that evokes the northern tundra with the trilling shattering glass song.

These marshy areas of wet machair (Machair Mhor, below Wee Totamore for example) are classy places. As you squelch through with birds all around the air turns heavy and fragrant with the smell of mint. The plant life is just superb. Wettest areas are spiked with the delicate whites and pinks of bog bean flowers and the water itself, though shallow, swirls with strands of stonewort - a weird and strangely alluring plant that becomes crispy coated with calcium carbonate from the lime-rich waters.

Down in these open water pools lurk the bladderworts, looking all coy and pretty with their delicate yellow flowers emerging on long stalks. But look below the surface and their true character is revealed. Long runners covered with air-filled bladders criss-cross the pool like a web. Any bumbling mini-beast that bumps the trigger causes the trap door in the bladder to flick open, sucking water and the wee beastie into the bladder. The trap door clangs shut, acidic juices are pumped into the bladder and the unfortunate victim is dissolved and digested.

Yet these vibrant places, with their damp fringe that turns an incredible colour in August - the purple carpet of devil's bit scabious studded and shimmering with grass of parnassus, these jewels are lost when some hulking great machine sticks a drain through them. A crying shame and almost indefensible now that wetlands are so rare and so many grants are available to compensate for any potential loss of farm profit.

The sun is now well up and other folk are beginning to appear. But the magic of the early dawn has gone. The light is now harsher, the bird song has gone, the tractors cough into life. But the sun still shines. I can't go to my bed when the sun shines. There is a long winter only recently escaped from. Seize the day!

I try to follow the fortunes of many of Coll's more exotic birds. Little terns on the beaches, red-throated divers on the hill lochs, arctic skuas on the moorland. All a far cry from the winter months when I'm busy with 1001 estate work tasks from fixing fences and gates, to shovelling manure and nettles into comcrake corners, to struggling with the computer trying to make it digest and regurgitate my year's data.

But it's still summer and what better than a lunch break on a 2000 year old Dun on a high coastal promontory looking to Rum and Skye over a glassy sea bumped with porpoises, pierced by white shards of gannets and gently undulating with uncountable shearwaters. Below in the glistening tangles a mother otter teaches a piping baby how to catch crabs.