There were 500 of them all together, black and white on dulled silver. And earlier there was that lone voice, sobbing to the heavens. It was clear, then, that time is not merely linear, and for that matter, not merely cyclical. One season does not only follow another: seasons also lie one on top of the other, in an endless and complex stratigraphy.

This was the first week of spring. It was also yet another of the eternal weeks of winter. Anyone who knows wildlife sees time as something chunky, funky, variable, untrustworthy. Spring has unquestionably begun: winter is without doubt still with us. This is not mere fancy, this is not neo-Proustian whimsy: this is a matter of hard observation.

This week, for the first time this year, I heard new voices in the air as I did the morning chores. Robins sing all year, and sparrows seldom shut up, but now more music came in to make this a multilayered thing. First, the short, thrilling drum solo of a great spotted woodpecker: a machine-gun celebration of the year's turning.

I stopped to see if I had imagined it, because it is done in an instant of time, and the old tease kept me waiting. But then at last he obliged again with an unmistakable rapid rattle. As if it was a signal, a great tit joined in. Then blue tit and coal tit. It was not unseasonably warm, it was merely time to begin: time that winter was overlaid with spring.

So then, high and wild and marvellously sweet, a mistle thrush threw his voice into the mix: a song that always seems to me to be the bravest of them all, more musical than the others and so wonderfully early, taking the challenge to winter and positively insisting that the seasons change at his behest.

But winter continues undaunted. Out on the matt-silver waters of the Alde estuary, I counted 500 avocets, forming a vast black-and-white high-tide raft. They were once extinct as breeding birds in this country, now they are part of daily life, effortlessly at home on the Suffolk coast. But they had no idea at all that spring had sprung: for them it was still midwinter, a time for hanging about in flocks and waiting for the moment to move on to their breeding grounds, to seek the love of their year and raise fluffy little scraps of life.

The low winter sun behind my shoulder lit the narrow bridleway as if with a searchlight, and it revealed thousand upon thousand. More little scraps of life: these ones would be invisible if there weren't so many, almost comically fragile.

In summer you'd call them a swarm of midges and think no more about them, because there is so much more to catch your eye. But at this time of the year they demand attention. They are winter gnats, braving the cold weather and the short days to emerge as daring sexual beings, to dance for a week or two in these mating swarms, find true love and breed, all before the insect-eating birds have hungry mouths to feed and an insect can get a bit of peace and quiet.

So in this almost indiscernible gap between the seasons, the winter gnats steal their lightning-swift breeding

season: dance, sex, death. A new generation will hatch out safe in the leaf litter. Overhead, a flock of 30 lapwings flew on, convinced it was still winter, and then, at the last, from the highest summit possible, a precious spring fragment of mistle thrush song.

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