Thousands of years ago, ancestral rails landed on Laysan, an isolated coral island in the Northwestern Hawaiian Islands. In an environment completely devoid of terrestrial mammalian predators and competing land mammals, flight was an expensive energetic investment with no adaptive advantage. Over generations, natural selection favored birds with reduced pectoral muscles and shorter wings, giving rise to the Laysan rail (Zapornia palmeri).
This small, highly active insectivore thrived in the island's dense tussock grass, laying eggs in well-hidden ground nests and foraging freely across the atoll. However, evolutionary isolation left the species catastrophically vulnerable to novel environmental disruptions. In the late 19th century, European settlers introduced domestic rabbits to Laysan to start a canned meat business.
Lacking natural controls, the rabbit population exploded, stripping the small island of virtually all vegetation within a few decades. Without plant cover, the habitat collapsed, causing the rail population on Laysan to crash. In a desperate conservation attempt, scientists translocated small groups of rails to nearby Midway Atoll.
Tragically, during World War II, military logistics led to the accidental introduction of black rats to Midway. Flightless, ground-nesting, and possessing no innate defensive instincts against mammalian carnivores, the remaining Laysan rails were wiped out entirely by 1944, marking the end of a unique evolutionary journey.