Michael McCarthy: Pity the poor vole, swallowed whole

Nature Notebook: Herons are marvellous birds to us, but to small creatures around them they are truly terrible

We just missed it: a striking instance of nature being red in tooth and claw, or in this case, beak. My 12-year-old son and I were at the Wetland Centre in Barnes, south-west London, that richest of all urban nature reserves, when we came across a small crowd gathered on a bridge over a watercourse, gazing intently at something. It was a heron; it was standing in the water, alert for prey, a mere 10 feet from us, remarkable enough in itself, but not as remarkable as the drama which had taken place a few moments earlier. Someone said: "It's just eaten a water vole."

What, Ratty? Fish, sure. Frogs, OK. But for a heron to make a meal of the charming hero of The Wind In The Willows seemed somehow ... outrageous. A crime, almost. There was no doubt, however, for there on somebody's digital camera was the image of the heron holding what was indisputably a water vole in its beak, prior to swallowing, and I imagined I saw a pitiable look in Ratty's eyes which said: "Good bye cruel world!"

Herons are mysterious, marvellous birds to us, but to small creatures around them they are truly terrible: that great stabbing stiletto of a bill can be turned on anything which comes within range, and even moorhens can be swallowed hole. There are lots of herons in Barnes, and three years ago they committed what to me was an even greater crime: they wiped out a family of avocets, the loveliest of wading birds, which had nested on one of the pools. Avocets breeding in London! It was a wonder... until all four of the chicks became heron dinners.

But what can you do? Even if they're eating water voles, Britain's most rapidly declining mammal, specially introduced into Barnes as a safe haven; even if they're eating avocet chicks and thus snuffing out an incipient colony, you can't shoot the herons on a nature reserve. They're part of it. I think all you can do in the end is gulp, and grit your teeth, and admit to yourself, it's a tough world.

A poetic observation

With their silence and slowness, their almost ritual stealth, herons definitely have an air of mystery about them. Dylan Thomas compared them to priests, and in his "Poem in October" you find a line I have always loved: "the mussel pooled and the heron priested shore". There's a poet nobody reads any more, eh?

Fifty years ago he was as big as the biggest rock star; now his modernist take on romanticism rings no bells, strikes no chords, seems insufficiently knowing or cynical for today's sensibility. But he's still out there.