The steep sides of the ravine amplify the dawn chorus above the rush of the Crumlin River, which tumbles over black basalt from its source on Divis Mountain to its mouth at Lough Neagh. I look up at the first hesitant trills of a blackcap. His stutter climbs to a few clear notes, then babbles to a halt, as if the bird were suddenly shy of the liquid beauty of his own song. I stop to listen for more. At first there’s only silence – then another outburst. It could be the same bird, gaining confidence; or it might be his neighbour, anxious to remind him of their territorial boundary. Either way, the voice is directly along this riverside path. I go on. Sylvia atricapilla, the species’ Latin name, is a more evocative appellation than the rather deadpan “blackcap”. While atricapilla – referring to the male’s black crown – means “black-haired”, Sylvia means “woodland sprite”. There is definitely an impish quality to the bird’s movements as his chuckling song teases me through sunlit foliage. I pass a weir, a relic of the days when the river powered mills. Now that they are gone, the glen has rewilded into this liminal refuge of deciduous woodland. My gaze scans in vain for the blackcap. As I get closer, he falls quiet again. I wait. He resumes just a little further ahead. That song. It dances like sunlight through a wind-stirred canopy and froths like a stream in spate. Its musicality reflects that it is largely adapted for transmission in an environment full of obstacles – pure tones are less distorted when they bounce off leaf and bark. The opening bars (known as the warble part) may sound as if a blackcap is just clearing his throat for the gorgeous second half (the whistle part). However, there is meaning attached to both parts of the song. Like a postcode, the pattern of notes in the whistle part is shared between a bird and its neighbours. The less audible warble notes are more idiosyncratic. They suggest more private information, possibly including a blackcap’s identity. I stare blindly up into the leaves. Could I be eavesdropping on a bird that is whispering his own name?