It was the perfect day for a walk on the coastal path at Holkham in North Norfolk. The sun was warm, the sky a bright, clear blue, but the air was crisp and fresh and humming with Spring life. As we walked along the dunes backing the beach, closing our eyes occasionally to enjoy the warmth of the sun on our faces, we were stopped in our tracks by the song of a skylark.

It took us a few moments to actually spot the skylark. The glorious waterfall of notes appeared to be coming from the air itself, but eventually our eyes found the tiny, fluttering shape, slowly spiralling up as it sang. The thought hadn’t occurred to me before, but the name skylark is so apt. When you first think about it, it seems oddly redundant — surely most birds are sky-somethings? — but no British bird is more part of the sky or more difficult to distinguish from it than the skylark. And their song is astonishing. It bubbles and cascades, with trills and flourishes that seem to refract the air as a prism does the light. To stand beneath a singing skylark is to stand in a cone of sound, getting drenched by notes which soak the dry earth beneath you. And yet we are able to hear only a small part of the complexity of that song. Our ears cannot resolve all the phrases, the slurs, the trills, and the baroque ornamentation that you can distinguish with the aid of a spectrogram. So much more complexity is hidden beyond the limitations of our hearing.

As we looked up at the bird, soaking up its song like sunlight, it stopped — mid-phrase — and at that moment the bird itself seemed to disappear back into the air. It was like watching a burning ember rising in the heat from a bonfire at night. Once the ember has burned out, the cooling material drifts on, but we can no longer see it. When the skylark is singing, we do not hear the full beauty of its song, but once it stops singing, we cannot even see the bird itself. The song makes the skylark visible.