'That Gadwall will be the cleanest duck on this lake,' said the bird photographer sitting next to me in the hide, 'it's been preening for twenty minutes now. I've taken about 70 pictures and I think I've got one decent one!'

His telescope with a Leica digital camera mounted on it (or was it camera with a telephoto lens mounted on it?*) struck me as a ideal for birdwatching as you can instantly take an image of any bird you're having difficulty identifying.

But when drawing the awkward poses adopted by a preening duck are more fun than your standard field guide poses. When a bird stands on one leg and fans out a wing or its tail you get more clues to its structure than when the feathers present a smooth surface.

* Apparently it's called 'digiscoping'