The smallest of the prions. Its bill is thinner and more pointed than its relatives. Like a needle compared to a spoon. The thin-billed prion is a small, grey-and-white seabird. It filters krill from seawater. It is abundant across the Southern Ocean. The population is measured in the tens of millions. It is widespread. It is common. It is also little known because it lives far from human habitation. The obscurity is geographic. The numbers are vast. The plumage is grey above. It is white below. A dark M pattern crosses the upperwings. The tail tip is dark. The bill is narrow and pointed. It is specialised for filtering smaller prey like copepods. The adaptation is specific. The morphology suits the diet. The form follows function. Feeding involves almost exclusively crustaceans. The bird filters them from the water using fine lamellae inside the bill. It flies low. The head is submerged. It paddles forward with its feet. A prion feeding is a bird converting seawater into protein. The process is efficient. The energy gain is critical. The method is unique. Flight is rapid and erratic. The wingbeats twinkle. A thin-billed prion in a storm is in its element. The wind does not deter it. The bird uses the turbulence. It rides the gusts. The movement is unpredictable. The control is innate. Breeding takes place on remote subantarctic islands. 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 krill oil. It fledges in about two months. The cycle is quick. The departure is timed. In New Zealand, these birds breed on the Antipodes, the Aucklands, Campbell, and the Snares. The populations are enormous. Millions of birds exist. The density is high. The presence is overwhelming. This is the most abundant prion in the Southern Ocean. It is also the least known. It lives far from people. The distance ensures silence. The scale is immense. The main threat is introduced predators. Rats and mice have wiped out populations on some islands. The subantarctic islands are mostly predator-free. The absence of mammals is critical. The protection is real. The call is a low, purring chatter. It is heard only at night on the breeding islands. The sound is pervasive. The atmosphere is heavy. The presence is marked. It carries on.