A Lightning Lark is the size of a field lark, streaked brown and grey above and pale beneath, with a short crest that stands straight up when the air is charged. Its wing feathers are edged with a fine blue sheen that glows faintly between flashes. Its song is the thing travellers remember: a thin, rapid, high trill, heard in the gaps of the endless thunder, that seems to rise and fall in time with the bolts. A flock smells sharply of ozone and singed feather.

They nest in the fissures of the blackened, glass-like plain and gather round the crystal rods that jut from it, where the bolts rise most often. They are common across the plain and thin out towards the storm’s core.

They feed on the glowing mites and dust-flies that the charged ground draws up, and catch them on the way down. When a rod begins to crackle, the flock crouches round it; as the bolt leaps, they leap with it, and are carried up into the cloud in a scatter of sparks. Then they fall, wings half closed, singing, and pull out just above the glass. They take no notice of travellers, except to dart away from anyone carrying metal.

They are not struck by the bolts they ride. They seem to feel a strike coming a moment before it rises, and to choose their place beside it. Their weight hardly matters to them in the Storm Heart’s patches of weakened gravity, and they float there for long moments without beating a wing.

Pairs lay three or four speckled eggs in a fissure lined with fused glass threads; the young ride their first bolt within a month of hatching. Many do not come down. An old lark’s feathers burn to blue at the tips.

They are harmless and useful. A flock crouching suddenly round a rod is the best warning of a strike that a traveller on the plain will get, and those who learn to read them move away when they do. Their song carries a little way through the noise, and guides on the plain say a traveller who can still hear the larks is not yet too near the core.

Visitors say the larks carry the travellers' prayers up into the storm, and that a lark which does not come down has taken someone’s message all the way. The Storm-Walkers are said to speak of them as children of the storm. Whether a lark’s feather carried out of the zone keeps its charge, as some claim, is not known.