A dark shearwater that flies over the Southern Ocean in flocks of millions. It is a river of birds flowing from New Zealand to the North Pacific and back every year. The sooty shearwater or tītī is one of the most abundant seabirds on the planet. It is also one of the most important to Māori. They have harvested its chicks for centuries. The scale is vast. The tradition is old. The plumage is uniformly dark grey-brown. It looks black in most light. The underwings flash pale silver when the bird banks. At first glance the bird is unremarkable. But it is extraordinary. It migrates from New Zealand to the North Pacific and back annually. The round trip covers 40000 kilometres. The distance is immense. The endurance is total. Feeding involves fish squid and crustaceans. The bird dives from the surface or plunges shallowly. It follows fishing vessels. It takes discards and offal. A sooty shearwater behind a trawler is a common sight. The association is opportunistic. The benefit is mutual. The scavenging is efficient. The food is secured. Flight is rapid and direct. Stiff wingbeats alternate with short glides. A sooty shearwater in a storm is in its element. It does not fight the weather. It uses it. The wind provides lift. The turbulence is navigated. The mastery is innate. The bird thrives in chaos. Breeding takes place on remote islands off the New Zealand coast. The burrow is dug into soft soil on a steep slope. A single white egg is laid. Both parents share incubation duties. The chick is fed on regurgitated fish oil. It fledges in about three months. The growth is steady. The departure is timed. The cycle repeats. After breeding the sooty shearwater migrates to the North Pacific. It winters off Japan Alaska and California. It crosses the equator twice a year. The journey is hemispheric. The range is global. The movement is predictable. The timing is precise. The population is declining. Climate change is the main threat. Warming seas shift the distribution of krill and fish. The birds have to travel further to find food. The consequence is energetic cost. The impact is significant. The trend is downward. The future is uncertain. The tītī harvest is regulated by Ngāi Tahu and the Moriori. The harvest is sustainable. It is carefully managed to ensure the birds persist. The protocol is traditional. The oversight is strict. The balance is maintained. The resource is protected. The call is a low moaning croak. It is heard only at night on the breeding islands. The sound is pervasive. The atmosphere is heavy. The presence is marked. The communication is simple. It carries on. This is a bird of the long journey. It flies further than almost any other bird on Earth. The mileage is record-breaking. The effort is relentless. It keeps going.