The Maori name for the island is Takapourewa - from takapou, the matipo trees that once blanketed the slopes, and rewa, meaning to float. The matipo grew so densely and so close to the water's edge that the island appeared to hover above the sea. Captain James Cook sailed past in 1770 and named it after Sir Philip Stephens, Secretary of the British Admiralty Board. The island sits in Cook Strait, between the North and South Islands, guarding the entrance to Tasman Bay. At 183 metres elevation, it offered an obvious site for a lighthouse, and the Colonial Marine Department first proposed one in 1854. It took the wreck of the bark Weathersfield nearby to revive the idea, and the light was finally built and first lit on 29 January 1894.

What happened next became one of conservation's most notorious cautionary tales, though the popular version is not quite accurate. The story usually stars a single cat named Tibbles, who singlehandedly drove Lyall's wren to extinction. The reality is messier and sadder. David Lyall's cat - whether named Tibbles or not, historians are uncertain - was likely pregnant when she arrived on the island. Her offspring and possibly other cats brought by lighthouse staff quickly went feral. Over the course of 1894, at least ten wren specimens were brought in by cats and sent to scientists. Two to four more appeared in 1895, and a handful after that, possibly as late as 1899. The feral cat population exploded, and Lyall's wren was not their only victim - the cats silenced the island's tui, bellbirds, and saddlebacks as well. By the time the cats were eventually eradicated, the damage was total. Lyall's wren had been a flightless bird on an island that, for millions of years, had no mammalian predators. It had no evolutionary preparation for what walked off the lighthouse keeper's boat.

The lighthouse itself is a feat of stubbornness. At 183 metres above sea level, it is the highest-elevation lighthouse in New Zealand, and the original components were shipped from Edinburgh at an eventual cost of 9,349 pounds - twice the price of most New Zealand lighthouses of the era. The white cast-iron tower flashes once every six seconds, its beam reaching 18 nautical miles across Cook Strait. The light was not automated until 31 March 1989, making it one of the last staffed lighthouses in the country. Today it is operated remotely from Maritime New Zealand's Wellington office. In 1947, the lighthouse appeared on a four-pence New Zealand postage stamp, a small moment of national recognition for an outpost most New Zealanders will never visit.

Stephens Island is now a nature reserve managed by the Department of Conservation, accessible only by permit. No people live there. But the island has become one of the most important refuges for tuatara, the ancient reptile that is the sole surviving member of an order that otherwise went extinct alongside the dinosaurs. With the cats gone and the island predator-free, tuatara thrive in densities found almost nowhere else. The forest is regenerating, and seabirds are returning to nest. The birdsong that the cats silenced is slowly coming back - though it will never again include the quiet rustle of a small, flightless wren running through the undergrowth. Lyall's wren remains a reminder of how quickly and completely a species can vanish when its only refuge is breached.