Inaccessible Island is an actual place and appropriately named as far as islands go. You can, however, access Inaccessible Island, technically, though it’s fiendishly difficult. It’s a steep-cliffed island some 2,175 miles from South America and 1,740 miles from South Africa. No airplanes fly near Tristan da Cunha, the island chain it’s part of, though it can be arranged to hitch a ride on a cargo or a research ship to anchor nearby. The journey to Inaccessible Island, regardless of point of origin, takes at least eight days of open ocean travel. Once anchored offshore, the only way to, ahem, access the island, is a tiny strip of beach barely suitable for a boat landing. Since conditions are so rough in the southern, exposed Atlantic, it’s only possible to go ashore Inaccessible Island a couple of days each year.
See? Pretty much inaccessible.
Scientists, though, have occasionally gone ashore there since the island was first located, and back in the 1920s, they reported something truly astonishing. A species of flightless bird lived there—they named it the Inaccessible rail. The island has only existed for a few million years—not enough time for a creature like this to evolve there independently. Weirder still, the bird wasn’t present on any neighboring islands in the chain. So, how the heck did they get there? It’s been a mystery for nearly a century.
A recent study may, however, have solved the riddle, with help from advanced DNA testing. It now seems the little rail devolved, if you will, the power of flight once it arrived on the island.
Researchers in 2011 sequenced the DNA of an Inaccessible rail and determined from that the origins of the bird were likely in South America, and that more than a million years ago the bird’s South American ancestors alighted on Inaccessible Island after what must have been one hell of a traumatic flight. Once there the birds were probably delighted to discover there are no native mammals on the island, so no reason to fear walking around on the ground, hunting for food.
“It seems the birds arrived on the island, and since they faced little threat from predators, there wasn’t much point of flying,” said Martin Stervander of the University of Oregon.
Sure, larger seabirds could be a threat, and there’s at least one other bird species that go after the Inaccessible rail’s eggs, but other than that, life is pretty sweet on Inaccessible Island for the little birds. So, the researchers think, over the million or so years they’ve been there, the birds have shelved their wings.
Back in the 1920s, perplexed scientists first wondered if the birds wandered over a land bridge that no longer connects Inaccessible Island to, well, anywhere. Turns out the true story is just as strange. Birds that no longer needed to fly simply lost their ability, through evolution to take to the skies, even for fun. Kind of a waste, when you think of it.
Top photo: Brian Gratwicke