Snow defines its breeding ground. Hutton's shearwater is a seabird that nests in the mountains. It is the only shearwater in the world that breeds above the tree line. Its burrows are dug into scree slopes in the Kaikōura Mountains. Altitudes range from 1,200 to 1,800 metres. A bird of the ocean returns to the snow to raise its young. The contrast is stark. The adaptation is unique. Plumage is typical for a small shearwater. Dark grey above. White below. A dark cap sits on the head. A dark patch appears under the wing. In flight, it moves with rapid, arcing wingbeats, low over the water. It does not look like a mountain bird. It does not need to. The appearance is pelagic. The behaviour is alpine. This duality defines the species. Feeding focuses on small fish and squid. Foraging occurs in coastal waters off eastern New Zealand. It follows fishing vessels. It takes discards. Diving happens from the surface or involves shallow plunges. The method is efficient. It relies on availability rather than pursuit. The bird exploits human activity when possible. This opportunism supports survival in changing oceans. Breeding season runs from September to April. The burrow is dug into loose scree, sometimes a metre deep. A single white egg is laid. Both parents share incubation duties. The chick grows slowly, fledging in April. Then it leaves. Winter is spent at sea. Return to the mountains occurs in spring. The cycle is annual. The location is fixed. The Kaikōura colony was once enormous. Early settlers reported that the shearwaters darkened the sky. Then pigs were introduced to the mountains. The pigs dug up the burrows. They ate the eggs. They ate the chicks. The colony crashed. Destruction was rapid. Recovery has been slow. The impact of introduced mammals is devastating in such specialised habitats. Conservationists intervened. They built a predator-proof fence. They removed the pigs. The shearwaters responded. The colony is recovering. Slowly. Intervention works when sustained. The fence provides security. The absence of pigs allows breeding to proceed. Monitoring continues. Vigilance is required. The threat remains latent. Frederick Hutton gives the species its name. He was a nineteenth-century scientist. He described the species from specimens collected in the Kaikōura Mountains. He was the first to understand that a seabird lived in the alpine zone. His observation corrected assumptions about shearwater ecology. Science advances through such corrections. Kaikōura tītī is the Māori name. Tītī is the general name for shearwaters. This one belongs to Kaikōura. The birds return to their burrows at night, calling to each other. The sound is a low, moaning chatter, echoing off the mountain slopes. On a dark evening in the Kaikōuras, the tītī fill the air. The auditory landscape is distinct. The population is still vulnerable. A single predator incursion could wipe out a colony. The birds have no other home. Restriction to one location creates risk. Conservation efforts mitigate this risk. They do not eliminate it. The species persists because people choose to protect it. That choice must continue.